proceedings of the - treenet - independent non-profit ... of adelaide, sardi, biometrics sa sa nsw...

Proceedings of the

13th National Street Tree Symposium 2012

ISBN: 978-0-9805572-1-3

TREENET Proceedings of the 13th National Street Tree Symposium 2012 Author/Contributor: Lawry, David; and Wojcik, Natasha (eds) Date of Publication: September 2012 ~ 110pp.

Contents Contents ..................................................................................................................................................... 1

INSTITUTIONAL MEMBERS OF TREENET 2012 ............................................................................................... 2

TREENET MANAGEMENT COMMITTEE AND ADVISORY BOARD 2011 ............................................................ 3

TREENET Incorporated Constitution ............................................................................................................. 7

Speaker and Panellist Profiles .................................................................................................................... 14

Trees as essential infrastructure: Engineering and design considerations* .................................................. 18

“Yeronga Memorial Park Project” .............................................................................................................. 32

The Burnside Village Tree – A Case Study of Construction and Tree Protection ........................................... 37

Myrtle Rust - Addressing the Challenge ...................................................................................................... 41

Cultural Significant Trees – A Management Tool for Local Government ...................................................... 63

Sustaining Urban Forest – Lessons from Laman Street, Newcastle .............................................................. 65

Flooding following Drought: a Swift and Subtle Killer of Stressed Trees ...................................................... 77

STUDENT POSTERS .................................................................................................................................... 91

Examination of tree water status of urban trees using thermal imaging ...................................................... 91

Introducing Green Roofs into the Urban and Built Environments of Adelaide .............................................. 97

The 13th National Street Tree Symposium 2012 1

INSTITUTIONAL MEMBERS OF TREENET 2012

ASSOCIATIONS Australian Institute of Landscape Architects SA (AILA SA) Institute of Australian Consulting Arboriculturists (IACA) Arboriculture Australia Ltd Local Government Tree Resources Association (NSW) Nursery & Garden Industry SA Inc (NGISA) Queensland Association of Arboriculture (QAA) South Australian Society of Arboriculture (SASA) Council Arboriculture Victoria

Adelaide City Council Albury City Council Brisbane City Council Campbelltown City Council City of Belmont City of Burnside City of Charles Sturt City of Holdfast Bay City of Marion City of Melbourne City of Mitcham City of Norwood, Payneham and St Peters City of Onkaparinga City of Playford City of Port Adelaide Enfield City of Salisbury City of Sydney City of Unley City of West Torrens

Active Tree Services Advanced Arbor Services Arbor Centre Arborman Tree Solutions Arbortrack Australasia Pty Ltd Austral Tree Services Department for Transport, Energy and Infrastructure Fleming's Nurseries Homewood Consulting HR Products

GOVERNMENT City of Yarra Corporation of the Town of Walkerville Department Planning Transport & Infrastructure District Council of the Copper Coast District Council of Mount Barker Gold Coast City Council Horsham Rural City Council Hume City Council Hurtsville City Council Moorabool Shire Council Moreland City Council Naracoorte Lucindale Council Newcastle City Council ACT TAMS and Parks & City Services Randwick City Council Rural City of Murray Bridge Toowoomba Regional Council Wagga Wagga City Council Whyalla City Council

CORPORATE Humphris Nurseries Metropolitan Tree Growers Pty Ltd Mt William Advanced Tree Nursery Quantified Tree Risk Assessment Limited (QTRA) Sydney Metro Tree Services TerraCottem Australasia Pty Ltd Tree Dimensions Treelogic Trentcom APS Pty Ltd Vermeer Sales and Service Pty Ltd

Click here to visit the TREENET website to find out more about our Institutional Members.


http://www.treenet.org/institutional-members

TREENET MANAGEMENT COMMITTEE AND ADVISORY BOARD 2011

TREENET MANAGEMENT COMMITTEE

Chairperson: Dr Greg Moore Director: David Lawry OAM (ex officio) Secretary: Dr Jennifer Gardner (ex officio) Treasurer: Robin Eley (ex officio) Members: Judy Fakes

Tim Johnson Brian Measday (ex officio) Hon Dr Bob Such MP John Zwar

TREENET

TREENET ADVISORY BOARD

David Lawry OAM Director TREENET and 1915- 2015 Avenues of Honour Project SA Brian Measday Chartered Accountant, Honorary Treasurer TREENET SA

Robin Eley Chief Financial Officer 1915- 2015 Avenues of Honour Project SA

Educational and Research Institutions Prof Chris

Judy

Dr Jennifer Trevor

Daniels

Fakes

Gardner

Hancock

Professor of Urban Ecology University SA Management Committee TREENET Head Teacher Parks, Gardens & Arboriculture Ryde College of TAFE. Management Committee TREENET Director, Waite Arboretum Management Committee TREENET University of Adelaide, SARDI, Biometrics SA

SA

NSW

SA

SA Dr David Jones Assoc. Professor Director Landscape Architecture, University Adelaide SA

Dr Greg Dr Dean

Moore

Nicolle

Research Assoc. Burnley School of Resource Management and Geography Chair TREENET Flinders University, Director, Currency Creek Arboretum

VIC

SA Dr Brian Richards Volunteer Waite Arboretum. Retired CSIRO soil scientist SA

Prof. Randy Stringer Professor Head of Discipline of Ag, Food and Wine University of Adel. SA

Debra Walkley Principal TAFE SA Urrbrae and Mt Barker Campuses SA

John Zwar TAFE SA Urrbrae Campus SA

Nursery Industry Ian

Brown

Mt William Advanced Tree Nursery

VIC

Ross Clark Trees Impact NSW John Fitzgibbon Metropolitan Trees VIC Geoffrey Fuller CEO Nursery & Garden Industry of South Australia SA Kevin Handreck Netherwood Horticultural Consultants SA Peter Lawton Trentcom VIC Hamish Mitchell Speciality Trees VIC


Community Hon Dr Bob Such Independent Member for Fisher SA

Management Committee TREENET

Arboricultural & Allied Professions Jan Allen Terra Ark QLD Peter Bishop Bunya Solutions QLD Rob Bodenstaff Arbor Centre WA Sam Cassar Symatree SA Sam Cowie Leaf and Limb Horticultural Consultancy Qld Stephen Frank Treelogic Pty Ltd VIC David Galwey Tree Dimensions VIC Craig Hallam ENSPEC SA Phillip Hewett Neighbour Woods NSW Ben Kenyon Homewood Consulting VIC Phillip Kenyon Kenyon’s Quality Tree Care VIC Kym Knight Tree Environs SA Michael Palamountain Tree Environs SA Mark Willcocks Active Tree Services NSW Sue Wylie TreeTalk Arboricultural Consulting NSW

Landscape Architects and Urban Planners Jared Barnes City of Adelaide SA Martin Ely Arbordesign SA Michael Heath Chair National Trust SA Significant Tree Committee SA

Legal Arnold Brian

Laurencis Preston

Civil & Commercial Barristers & Solicitors Pty Ltd Chief Justice of the NSW Land and Environment Court

SA NSW

Local Governments (users of research outcomes) David Craig Tim

Cooney Hinton Johnson

District Council of Mt Barker Frankston City Council, President ISAAC City of Mitcham

SA VIC SA

Bernard

Keays

Management Committee TREENET Moreton Bay Regional Council

QLD

Christopher Lawry District Council of Mt Barker SA Martin Norris Wellington Shire Council VIC Lyndal Plant Brisbane City Council QLD Deon Schumann City of Port Augusta SA Jason Summers Hume City Council VIC Karen Sweeney City of Sydney NSW

State Governments Kiah

Martin

Royal Botanic Gardens Melbourne, Women of the Trees

VIC Henry Polec Department of Transport Energy and Infrastructure SA TREENET David Lawry OAM Director TREENET and 1915- 2015 Avenues of Honour Project SA Brian Measday Chartered Accountant, Honorary Treasurer TREENET SA

Robin Eley Chief Financial Officer 1915- 2015 Avenues of Honour Project SA

Educational and Research Institu Prof Chris Daniels

tions Professor of Urban Ecology University SA Management Committee TREENET

SA


Judy

Dr Jennifer

Trevor

Fakes

Gardner

Hancock

Head Teacher Parks, Gardens & Arboriculture Ryde College of TAFE. Management Committee TREENET Director, Waite Arboretum Management Committee TREENET University of Adelaide, SARDI, Biometrics SA

NSW

SA

SA Dr David Jones Assoc. Professor Director Landscape Architecture, University Adelaide SA

Dr Greg Dr Dean

Moore

Nicolle

Research Assoc. Burnley School of Resource Management and Geography Chair TREENET Flinders University, Director, Currency Creek Arboretum

VIC

SA Dr Brian Richards Volunteer Waite Arboretum. Retired CSIRO soil scientist SA

Prof. Randy Stringer Professor Head of Discipline of Ag, Food and Wine University of Adel. SA

Debra Walkley Principal TAFE SA Urrbrae and Mt Barker Campuses SA

John Zwar TAFE SA Urrbrae Campus SA

Nursery Industry Ian

Brown

Mt William Advanced Tree Nursery

VIC

Ross Clark Trees Impact NSW John Fitzgibbon Metropolitan Trees VIC Geoffrey Fuller CEO Nursery & Garden Industry of South Australia SA Kevin Handreck Netherwood Horticultural Consultants SA Peter Lawton Trentcom VIC Hamish Mitchell Speciality Trees VIC

Community Hon Dr Bob Such Independent Member for Fisher SA

Management Committee TREENET

Arboricultural & Allied Professions Jan Allen Terra Ark QLD Peter Bishop Bunya Solutions QLD Rob Bodenstaff Arbor Centre WA Sam Cassar Symatree SA Sam Cowie Leaf and Limb Horticultural Consultancy Qld Stephen Frank Treelogic Pty Ltd VIC David Galwey Tree Dimensions VIC Craig Hallam ENSPEC SA Phillip Hewett Neighbour Woods NSW Ben Kenyon Homewood Consulting VIC Phillip Kenyon Kenyon’s Quality Tree Care VIC Kym Knight Tree Environs SA Michael Palamountain Tree Environs SA Mark Willcocks Active Tree Services NSW Sue Wylie TreeTalk Arboricultural Consulting NSW

Landscape Architects and Urban Planners Jared Barnes City of Adelaide SA Martin Ely Arbordesign SA Michael Heath Chair National Trust SA Significant Tree Committee SA

Legal Arnold Laurencis Civil & Commercial Barristers & Solicitors Pty Ltd SA


Brian Preston Chief Justice of the NSW Land and Environment Court NSW

Local Governments (users of research outcomes) David Cooney District Council of Mt Barker SA Craig Hinton Frankston City Council, President ISAAC VIC Tim Johnson City of Mitcham SA

Management Committee TREENET Bernard Keays Moreton Bay Regional Council QLD Christopher Lawry District Council of Mt Barker SA Martin Norris Wellington Shire Council VIC Lyndal Plant Brisbane City Council QLD Deon Schumann City of Port Augusta SA Jason Summers Hume City Council VIC Karen Sweeney City of Sydney NSW

State Governments Kiah Martin Royal Botanic Gardens Melbourne, Women of the Trees VIC Henry Polec Department of Transport Energy and Infrastructure SA


1. NAME

TREENET Incorporated Constitution

The name of the Association is "TREENET Incorporated"

2. DEFINITIONS

2.1 “The Act” means the Associations Incorporations Act 1985.

2.2 “Association” means the above named Association.

2.3 “Management Committee” means the committee referred to in Rule 11.

2.4 “Advisory Board” means the Board referred to in Rule 12.

3. VISION AND AIMS

3.1 Vision

The vision of the Association is to enhance the role of trees in the urban forest and to engage the community in this endeavour.

3.2 Aims

The aims of the Association are:

3.2.1 To develop and maintain an interactive web application to facilitate the exchange of information relating to urban forests.

3.2.2 To promote research and education relating to urban forests including holding symposia.

3.2.3 To establish and maintain a public fund to be called TREENET Fund for the specific purpose of supporting the environmental purposes of TREENET Inc. The Fund is established to receive all gifts of money or property for this purpose and any money received because of such gifts must be credited to its bank account. The Fund must not receive any other money or property into its account and it must comply with subdivision 30-E of the Income Tax Assessment Act 1997.

4. POWERS

The Association shall have all the powers conferred by Section 25 of the Act.

5. MEMBERSHIP

5.1 Membership

When an organisation or person has agreed to become a member of the Association and has paid the Association’s membership fee where it applies, then that organisation or person will be admitted to membership pursuant to the Constitution, and their name shall be entered in the Association’s Register of Members.

5.2 Classes of Member

There shall be five classes of member:

5.2.1 Management Committee Member

This class shall consist of all members of the Management Committee as described in Rule 11.1. Management Committee Members will have the right to receive notice of and attend all meetings.


5.2.2 Advisory Board Member

This class shall consist of natural persons who have been invited by the Management Committee to be on the Advisory Board and agreed. Advisory Board Members will have the right to receive notice of, and attend, the Annual General Meeting and other General Meetings as called. The term of appointment will be for the calendar year.

5.2.3 Associate Member

This class shall consist of natural persons who register an interest in joining the Association and who subscribe to the aims of the Association.

5.2.4 Institutional Member

This class shall consist of research and educational institutions, government bodies, businesses and associations who are financial members. Institutional Members will have the right to receive notice of, and attend, the Annual General Meeting and other General Meetings as called.

5.2.5 Honorary Life Member

This class shall consist of natural persons who have been granted Honorary membership at the discretion of the Management Committee. Honorary Life Members will have the right to receive notice of and attend the Annual General Meeting and other General Meetings as called.

5.3 Votes

Members may exercise the following voting entitlements:

5.3.1 Management Committee Member – 1 vote

5.3.2 Advisory Board Member – 1 vote

5.3.3 Associate Member – members of this class shall have no votes

5.3.4 Institutional Member – financial members – 1 vote by representation or proxy

5.3.5 Honorary Life Member – 1 vote

5.4 Register of Members

A Register of Members shall be kept which contains the name, postal or electronic address, class of membership and subscription details of each Member and the date of joining the Association.

5.5 No Transfer of Rights

The rights and privileges of a Member shall not be transferable and shall cease upon such an organisation or person ceasing to be a Member.

6. MEMBERSHIP FEES

The Management Committee shall from time to time set the terms and conditions of membership fees, if any, for the different classes of membership.

7. CESSATION OF MEMBERSHIP

Membership may cease by resignation, expulsion or non payment of fees.

7.1 Resignation

Members shall cease to be a member by notifying the Association by whatever means the Management Committee might direct from time to time.


7.2 Expulsion

If any Member wilfully refuses or neglects to comply with the provisions of the Constitution, or is guilty of any conduct which in the opinion of the Management Committee is unbecoming to a Member or prejudicial to the interests of the Association, the Committee shall have the power to expel the member from the Association PROVIDED THAT at least one month before the Committee Meeting at which a resolution for the Member’s expulsion is to be considered, the Member shall have been given notice of such meeting and what is alleged against them and of the intended resolution for their expulsion, and they shall at such meeting and before the passing of such resolution have had an opportunity to give oral or written explanation for their defence.

7.3 Non-payment of Fees

If a Member has not paid fees as agreed in the terms and conditions and has been notified in writing by the Association of this failure, then the Member shall cease to be a Member of the Association unless the prescribed fee is paid by the date as notified.

8. PROPERTY AND FINANCE

8.1 The funds and other property of the Association shall be managed and controlled by the Management Committee and shall be used only for the vision and aims of the Association.

8.2 All cheques, negotiable instruments and orders drawn by the Association shall be signed by two persons designated by the Management Committee.

8.3 Subject to Rule 8.1, the surplus funds of the Association may be invested in such manner as the Management Committee sees fit, except direct equities.

8.4 The accounts of the Association shall be audited annually.

8.5 The financial year of the Association shall be from 1 July to 30 June.

8.6 The Association shall prepare financial accounts at the end of each financial year.

9. NOT-FOR -PROFIT

The assets and income of the Association shall be applied solely in furtherance of its above- mentioned vision and aims and no portion shall be distributed directly or indirectly to the members of the Association except as bona fide compensation for services rendered or for reimbursement for expenses incurred.

10. MEETINGS OF THE ASSOCIATION

10.1 The Annual General Meeting shall be held at such time as the Management Committee shall determine.

10.2 Any Motion that any voting Member proposes to move at the Annual General Meeting including a proposal to alter the Constitution shall be given in writing to the Management Committee at least four weeks before the meeting.

10.3 At least 21 days before the Annual General Meeting or any other General Meeting, notice shall be given by written or electronic form sent to all members of the Association entitled to vote, but any accidental omission to give notice to any voting member shall not invalidate the meeting.

10.4 At the Annual General Meeting, ordinary business shall be the presentation of the audited financial accounts, election of the Management Committee and the appointment of an auditor.


10.5 Each voting member present shall be entitled to one vote. In case of an equality of votes, the Chair shall have a second or casting vote.

10.6 A Special General Meeting may be requested by ten voting members presenting an agenda to the Management Committee, the agenda being signed by all ten members. The Management Committee must within 14 days give notice of a Special General Meeting to be at least 21 days from the notice date. The Special General Meeting will be limited to the agenda items plus other items of which the Committee gives notice. Once the agenda items have been resolved by consensus, resolution or vote they cannot be used again to call a Special General Meeting for 52 weeks from the meeting date.

10.7 An Advisory Board Member shall be entitled to appoint in writing a natural person, who is also an Advisory Board Member of the Association, to be his or her proxy, and to vote on his or her behalf at any general meeting of the Association.

11. MANAGEMENT COMMITTEE

11.1 Membership of the Management Committee

The Management Committee will comprise six elected members drawn from education and research, business and government sectors of the community and three ex officio members as follows:

11.1.1 An academic from a tertiary educational institution

11.1.2 A member of Local Government

11.1.3 Four other members

11.1.4 The Director of Waite Arboretum will be a member ex officio and may also represent The University of Adelaide with consent from the University

11.1.5 The Directors of Treenet and the Treasurer of Treenet will be members ex officio.

11.2 Elections

11.2.1 The elected members of the Management Committee shall be elected annually by voting members of the Association at the Annual General Meeting.

11.2.2 Where the number of candidates for membership of the Management Committee exceeds the maximum number, elections shall be held by secret ballot of members at the Annual General Meeting entitled to vote. In the case of an equality of votes, the Chair shall have a second or casting vote.

11.2.3 The nomination of a candidate for membership of the Management Committee must be in writing, signed by a proposer (who must be an Advisory Board member) and by the nominee. The nomination must be delivered to the Director of the Association before such time as the Management Committee shall determine.

11.2.4 Subject to Rule 11.1, the Management Committee shall have the power to co-opt further Committee members and to fill casual vacancies.

11.3 Office Bearers

The Office Bearers of the Association shall be:

Chair Director & Public Officer ex officio Treasurer ex officio

11.4 Procedures Generally

The Management Committee may meet in person or confer by video or telephone conferencing, email or by other electronic means for the dispatch of business and subject to the Constitution, otherwise regulate its meetings as it thinks fit.


11.5 Calling of Committee Meetings

11.5.1 The Management Committee shall meet or confer at least four times per year as described in 11.4. Notice of the meeting or conference shall be given in writing to each Committee Member.

11.5.2 The position of any Committee member absent for three consecutive meetings or conferences without leave of absence shall automatically become vacant. Acceptance of an apology shall be deemed grant of such leave.

11.6 Chair

The Chair shall take the chair at meetings. In his or her absence, the Committee shall appoint a member of the Committee to chair the meeting.

11.7 Decisions of Questions

Questions arising before a meeting of the Committee shall be decided by a majority vote. In case of an equality of votes, the chair shall have a second or casting vote.

11.8 Reporting

The Management Committee shall be responsible to the Association and shall present an annual report, including the audited financial accounts, to each Annual General Meeting.

11.9 Auditor

The Management Committee shall appoint an auditor of the Association, who will hold office until the next Annual General Meeting of the Association.

12. ADVISORY BOARD

12.1 There shall be an Advisory Board of the Association.

12.2 The Advisory Board will comprise persons who are competent and willing to provide advice to the Association in their individual areas of expertise, and to liaise with other bodies and institutions for the purpose of facilitating the flow of information between the Association and those other bodies and institutions, and facilitating the implementation of projects which the Association undertakes in furtherance of its aims.

12.3 Members of the Advisory Board shall have no power or authority to represent the Association in any dealings between the Association and third parties.

12.4 The Advisory Board shall meet at such times and places as the Management Committee shall determine.

12.5 The Chair of the Management Committee will take the chair at meetings of the Advisory Board.

13. QUORUMS

13.1 The quorum at general meetings of the Association shall be six members entitled to vote.

13.2 The quorum at Management Committee meetings shall be three members.

14. AUTHORITY TO ENTER INTO CONTRACTS OR AGREEMENTS

The Association shall not be committed to any binding contract or Agreement except pursuant to a resolution of the Management Committee and the instrument shall be signed by at least two members of the Committee.


15. DISSOLUTION

15.1 The Association shall be dissolved if a resolution to this effect is carried by a three-quarters majority voting in person or by proxy at a general meeting, 21 days notice of the proposed resolution having been given to all members entitled to vote.

15.2 In the event of the Association being dissolved, the amount that remains after such dissolution and the satisfaction of all debts and liabilities shall be transferred to the University of Adelaide, for expenditure on the Waite Arboretum only.

16. ALTERATION TO THE CONSTITUTION

This Constitution may be altered by resolution of a majority of three-quarters of members entitled to vote and who cast a vote in person or by proxy at a general meeting. Written notice of amendments shall be posted to all members entitled to vote at the same time as the notice of the meeting.

17. REQUIREMENTS OF THE PUBLIC FUND

The organisation must inform the Department responsible for the environment as soon as possible if:

• it changes its name or the name of its public fund; or

• there is any change to the membership of the management committee of the public fund; or

• there has been any departure from the model rules for public funds set out in the Guidelines to the Register of Environmental Organizations.

18. MINISTERIAL RULES

The organisation agrees to comply with any rules that the Treasurer and the Minister with responsibility for the environment may make to ensure that gifts made to the fund are only used for its principal purpose.

19. CONDUIT POLICY

Any allocation of funds or property to other persons or organizations will be made in accordance with the established purposes of the organisation and not be influenced by the preference of the donor.

20. WINDING-UP

In case of the winding-up of the Fund, any surplus assets are to be transferred to another fund with similar objectives that is on the Register of Environmental Organizations.

21. STATISTICAL INFORMATION

Statistical information requested by the Department on donations to the Public Fund will be provided within four months of the end of the financial year.

An audited financial statement for the organisation and its public fund will be supplied with the annual statistical return. The statement will provide information on the expenditure of public fund monies and the management of public fund assets.

22. RULES FOR THE PUBLIC FUND

22.1 The objective of the fund is to support the organization’s environmental purpose.


22.2 Members of the public are to be invited to make gifts of money or property to the fund for the environmental purposes of the organisation.

22.3 Money from interest on donations, income derived from donated property, and money from the realisation of such property is to be deposited into the fund.

22.4 A separate bank account is to be opened to deposit money donated to the fund, including interest accruing thereon, and gifts to it are to be kept separate from other funds of the organisation.

22.5 Receipts are to be issued in the name of the fund and proper accounting records and procedures are to be kept and used for the fund.

22.6 The fund will be operated on a not-for-profit basis.

22.7 A committee of management of no fewer than three persons will administer the fund. The committee will be appointed by the organisation. A majority of the members of the committee are required to be ‘responsible persons’ as defined by the Guidelines to the Register of Environmental Organizations.


Speaker and Panellist Profiles Dr Greg Moore Greg Moore was Principal of Burnley College of the Institute of Land Food Resources at Melbourne University from 1988 to 2007. Prior to this he had been a Senior Lecturer and Lecturer in Plant Science and Arboriculture at Burnley from 1979. He was Head of the School of Resource Management at the University from October 2002 to April 2007. Apart from a general interest in horticultural plant science, revegetation and ecology, Greg has a specific interest in all aspects of arboriculture, which is the scientific study of the cultivation and management of trees.

He is recognised internationally as one of the founders of the modern arboricultural movement and is widely sought after as a speaker, advisor, advocate and mentor. His keynote papers at past Treenet Symposia have been a major catalyst for the recent changes in attitudes and practices relating to Australia’s urban trees. His presentations are founded on his exceptional ability to pass onto his audience his thorough understanding of the subject at hand.

As Chair since 2005, Greg’s other major contribution is the orderly and efficient governance he brings to TREENET. His ability to think strategically and his wide experience in the management of not for profit organisations has been called upon to the benefit of many environmental and educational causes over the past 30 years.

He has contributed to the development of Australian Standards in pruning and amenity tree evaluation and has been a major speaker at conferences in Australia, Israel, Hong Kong, USA and New Zealand in recent years. He was the inaugural president of the International Society of Arboriculture, Australian Chapter. He has been a regular on Melbourne radio, particularly with ABC 774 and 3AW.

He has been a member of the National Trust of Victoria’s Register of Significant Trees since 1988 and has chaired the committee since 1996. Greg has been on the Board of Greening Australia (Victoria) since 1989 and has been an active member of various sub-committees of that organisation. He was involved with the Agriculture and Horticulture subject at VCE level setting several of the examinations. He has also served on a number of industry and TAFE sector committees, especially those that deal with curriculum and accreditation matters. He is currently supervising eleven post-graduate students and continues to pursue an active research profile in any matters that relate to trees in the urban environment and revegetation. He has written one book, contributed to another and has had some 80 papers and articles relating to tree biology and management published.

David Cooney David Cooney is currently a Senior Policy planner at the District Council of Mount Barker, one of the most rapidly expanding peri urban townships in Australia.

He has had extensive experience in Local Government in rural, urban and outer metropolitan areas in the fields of horticulture, environmental management and planning.

He was motivated by the lack of standard protocols in the identification assessment and management of culturally significant landscapes to initiate and head up an LGA funded review of current procedures and options for the future.


Sam Cassar Sam Cassar has experience and qualifications in Horticulture/Arboriculture and Landscape Design. These experiences include some 15 years in local government and six years in private practices.

Sam’s experiences in local government includes: Asset Manager Park Lands and Open Space for the City of Adelaide; Horticultural Planner for the City of Charles Sturt; and Senior Horticulturalist with the City of Norwood, Payneham and St Peters.

In 2006 Sam Cassar left local government and established Symatree Pty Ltd. Symatree is a consulting service providing Arboriculture, Landscape Design and Urban Horticultural services to both the public and private sectors. The services Symatree provides include:

• Significant tree assessment and advice; • Landscape design, specification development and implementation; • Management of trees on construction sites; • Tree audits and condition surveys; and • Tree and horticultural policy and procedural development and implementation.

Sam Cassar’s tertiary qualifications are pre-dominantly within the urban horticultural profession, including a Bachelor of Applied Science (Horticulture) and Associate Diploma (Horticulture) both obtained from Burnley College, now part of the University of Melbourne. Sam also has a Graduate Diploma in Design from the University of Adelaide, a trade level qualification in gardening from the Adelaide Botanic Gardens and Certificate IV in Workplace Training from Maxima. Sam was awarded the John Inglis Lothian Memorial Prize for excellence in Horticulture in 1991. Sam is also involved with the University of Adelaide engaged as a Tutor with the School of Architecture, Landscape Architecture and Urban Design. He has been tutoring for the past six years.

Philip Hewett Arboriculturist Email: [email protected] Mobile: 0411 754 115

For some 30 years Philip has been engrossed in private and municipal tree administration in town planning, landscape and asset management and tree preservation. In 1986, after four years as Tree Officer for Hobart City Council he joined NSW TAFE where he gained his teaching qualifications and taught horticulture at Ryde College. Four years later he left for another bout of municipal trees this time at Wyong Council. He later established an arboriculture consultancy before returning for a third foray into local government, this time at Newcastle. Now semi-retired, Philip still widely promotes the importance of urban forest to our urban communities. His numerous public presentations derive from extensive practical experience at the working interface of public trees, Council administration and the communities they serve. Philip was appointed Acting Commissioner in the NSW Land & Environment Court in 2010.


mailto:[email protected]

Chris Lawry Chris is the Urban Forest Officer for the District Council of Mount Barker which is located on rural land in the Adelaide Hills. The predominantly rural zoning is interconnected with rapidly expanding urban and peri urban townships. The Mount Barker township is the largest hills suburb which has often been described as the most rapidly growing non-coastal area in Australia.

He therefore has the responsibility of guiding Council and developers down the path toward creating a liveable city whist retaining as much of the precious remnant woodland resource and historic exotic rural landscape values as possible. Chris graduated from Burnley College in 2003 with a Diploma in Arboriculture.

Michelle Lensink Michelle Lensink has been a member of the Legislative Council since 2003. A Physiotherapist by profession, she became involved with the Young Liberals before securing a position with Federal MP Christopher Pyne and later Robert Lawson, the State Minister for the Ageing and Disability Services. Ms Lensink entered the Legislative Council following the retirement of Diana Laidlaw, who had wished to be replaced by a young woman. She is now the Deputy Leader of the Opposition in the Legislative Council and her portfolio responsibilities include Environment and Conservation, Sustainability and Climate Change, the Status of Women, Youth and Consumer Affairs.

Michelle Lensink has been a regular and knowledgeable attendee at recent TREENET Symposia and workshops and is working closely with TREENET and the SA Society of Arboriculture to ensure the new regulations to the Significant Tree Act protect the integrity of Adelaide's urban forest and set it on a sustainable course of management.

Deng Zijuan

School of the Environment Flinders University of South Australia Email: [email protected]/[email protected]

Academic Background

10/2009 –now PhD candidate in Hydrology of Flinders University

09/2006 -07/2009 Master of Engineering (Hydrology), China University of Geosciences (Beijing)

09/2002 -07/2006 Bachelor of Engineering (Environmental Engineering), China University of Geosciences (Beijing)


Dr Jennifer Gardner Jennifer has been the Director of Waite Arboretum since 1987. She has collaborated with David Lawry on the Treenet project since its foundation in 1997 and is on the Treenet Management Committee and Advisory Board. Jennifer is committed to the long term protection and on-going development of the Arboretum as a valuable experimental collection for research and education. She aims to promote its use to the widest community as well as a resource for landscape architects, planners, arboriculturalists, the nursery and allied industries.

David Lawry David Lawry is the Director of TREENET based at the Adelaide University’s Waite Campus. He also graduated from there in 1972 with a degree in Agricultural Science majoring in Horticulture. After a 3 year teaching stint he established his family nursery and commercial landscaping business specialising in Australian natives. Having been involved in many tree planting projects which he believed were ultimately unsustainable, David became interested in the science of establishing trees in urban settings, particularly street trees. This led to the co- founding of TREENET (Tree and Roadway Experimental and Educational Network) in 1997 with Dr Jennifer Gardner, curator of the Waite Arboretum. In 2002 an illness rescued him from his attempts to make money in business and he applied his management skills in not for profit organisations to the running of TREENET.

He also heads up his own company ‘Space Down Under’ which specialises in the development of root friendly environments for trees, based on the beneficial reuse of colloidal residues filtered from Adelaide’s reservoirs. His invention of the TREENET inlet has been greatly facilitated by the practical application of his PhD. He was awarded an Order of Australia Medal in the 2008 Queens Birthday Honours list. The citation reads: ‘For service to arboriculture and the environment, particularly through research and support for sustainable plantings in the urban landscape, and to the community through the Avenues of Honour project.’ OAM also stands for Only A Mug.


Trees as essential infrastructure: Engineering and design considerations*

Simon Beecham School of Natural and Built Environments and Centre for Water Management and Reuse

University of South Australia [email protected]

Abstract

One of the guiding principles of water sensitive urban design is mitigating the adverse effects of urban stormwater runoff such as increased urban flooding and deteriorating receiving water quality. Street trees can be used as water sensitive urban design measures and they have been shown to substantially reduce nitrogen and other pollution loads in stormwater. However, urban planners and local council designers have often been reluctant to include trees as part of their urban street designs in the past due to the susceptibility of pavements to damage by tree roots. Permeable pavements may offer a solution to a number of the common problems associated with incorporating street trees into urban landscapes.

This paper reports on a new experimental research project to assess and quantify the long-term performance of permeable pavements in reducing stormwater flows and pollution loads, reducing the incidence of structural damage to pavements by tree roots and in promoting healthier and faster growing trees under typical Australian conditions. Three separate paving configurations were used in the field trials; two pavements were constructed as permeable pavements and the third was constructed as a typical impermeable pavement. Initial experimental results are presented and these suggest that trees planted with permeable pavement surrounds generally have a higher growth-rate than trees planted with impermeable surfaces.

WSUD and Street Trees

Water sensitive urban design (WSUD) aims to achieve integrated water cycle management for the development or redevelopment of urban areas. One of the guiding principles of WSUD is mitigating the adverse effects of urban stormwater runoff such as increased urban flooding and deteriorating receiving water quality (Lucke, 2011) Local government authorities now routinely incorporate various treatment devices into the urban landscape as stormwater best management practices (BMPs) to assist in achieving WSUD objectives.

One of the main problems associated with stormwater discharge is the negative impacts that its high nutrient levels can have on downstream aquatic environments (Denman et al., 2006) Elevated nutrient levels in stormwater contribute to eutrophication of streams and coastal environments and this can have devastating consequences for aquatic marine life (Islam and Tanaka, 2004) Stormwater treatment by WSUD measures such as biofiltration systems, vegetated swales and other vegetated devices have been shown to significantly reduce the nutrient loadings in stormwater runoff (Hatt et al., 2009; Davies, 2007) However, vegetated WSUD treatment systems generally require a significant footprint to function correctly and this is often difficult to provide in typically congested urbanised areas.

Street trees are a highly desirable part of the urban landscape that can also be used as WSUD measures. As part of their natural growth cycles, they have been shown to substantially reduce nitrogen and other pollution loads in stormwater (Denman et al., 2006; Read et al., 2010) Street trees are also known to significantly reduce stormwater runoff volumes from urban catchments (McPherson et al., 1999) Street trees can therefore offer the same or improved environmental benefits as bioretention and other vegetated systems. However, they do so without taking up excess valuable urban street space. The other significant benefits of urban street trees, such as their aesthetic value and their social and economic benefits are also well documented (Roberts et al., 2006)



Street Tree Issues

In the past, urban planners and local council designers have often been reluctant to include trees as part of their urban street designs as there has been a perception that this increases overall lifecycle costs, particularly due to pavement damage by tree roots (McPherson and Peper, 1996) If the value of trees was considered at all, it was generally only for their amenity value and this was readily discounted against future potential maintenance costs. The economic implications of this damage are substantial and can include infrastructure maintenance and replacement costs, risk of potential injury and associated claims, administrative costs, poor public relations, reduced property values and reduced tree health and longevity.

A study of the infrastructure repair costs of municipal councils in 15 different US cities was undertaken by McPherson and Peper (1996) They reported that the cost for repairing infrastructure damaged by street trees consumed an average of 25% of the total tree budget allocated for these cities. However, they also recognised that these maintenance costs were conservative as sewer repair and other costs borne by home owners were not included in these estimates. Various other studies have reported on the significant structural damage caused by tree roots (Hamilton et al., 1975; McPherson, 2000; Costello and Jones. 2003; Randrup et al., 2003) and the associated economical impacts of that damage.

There are a number of factors that can contribute to preventing healthy street tree growth in urban environments. Air pollution, poor drainage and damage by people and vehicles can shorten the life expectancy of urban trees (Smiley et al., 2006) However, a lack of suitable soil conditions to promote root growth is the most common cause of poor tree health. The high levels of soil and base course compaction required to support the pavement loadings can become problematic for a tree that is planted close to pavement (Grabosky et al., 2009) The compacted soil often hinders or excludes root growth by limiting their access to the water and mineral resources contained in the soil.

To address the issue of compacted soils limiting tree root growth, a variety of structural soils have been developed in recent years (Smiley et al., 2006; Grabosky et al., 2009) These structural soils have been used as alternatives to typical compacted soils and often contain large proportions of aggregate to bear the weight of the overlying pavement and vehicular traffic in urban areas. Other materials have also been successfully used to minimise the effects of soil compaction on urban tree root growth. Smiley et al. (2006) conducted a study on tree growth in a variety of structural soil types and also trialled a method of suspending a pavement on piers above an uncompacted soil. They found that trees planted in non-compacted soil beneath the suspended pavement were generally larger, faster growing, healthier and had more root growth than in the other treatments.

Randrup et al. (2003) suggested that certain pavement construction methods may even promote damage to pavements by tree roots. They explained that a concrete or asphalt pathway can act as a barrier that prevents soil moisture loss by evaporation. This evaporation barrier causes the soil moisture to condense on the underside of the pavement because of temperature differences between the soil and the pavement. Tree roots are therefore naturally attracted to the condensation at the soil/concrete interface and this leads to pavement surface damage through the radial forces generated during root growth. Randrup et al. (2003) proposed that pavements constructed from porous materials that limit condensation and lower the temperature under concrete slabs may reduce the incidence of rooting at the interface and the subsequent damage this can cause.

There has been considerable research on the negative environmental impacts of treeless streets (including enhanced heat island effects) and growing concerns about the impacts of climate change have helped bring about a change in attitude toward urban street trees by town planners and designers (Shashua-Bara and Hoffman, 2000) The considerable economic and environmental benefits that urban street trees provide are now being duly recognised. Recognition of the fundamental role that street trees play in urban environments has led to research into new methods of implementing street trees that have potentially lower maintenance costs and that promote healthier and faster growing trees.

Permeable Pavements and Street Trees

Permeable pavements may offer a solution to a number of the common problems associated with incorporating street trees into urban landscapes. Permeable pavements allow stormwater to infiltrate through the paving surface where it is filtered through the various layers and then either harvested for later reuse or


released slowly into the underlying soil or downstream stormwater drainage system (Lucke and Beecham, 2011) Permeable paving can be used as an alternative to the conventional hard, impervious surfaces that typically surround trees in footpaths, roadways and carparks. Providing that permeable pavements are correctly designed and installed, they have the potential to successfully minimise the incidence of pavement damage by tree roots, to promote healthier and faster growing trees and to reduce stormwater runoff and pollution loads from urban areas.

Figure 1 shows a comparison between a typical street tree configuration planted under a concrete or asphalt pavement and a street tree configuration planted within a permeable pavement.

Typical Concrete or AC Pavement

Roots Typically Seek Out

Moisture Under Pavement (Pavement Damage)

Permeable Pavement

Roots Do Not Penetrate into Dry Gravel Zone (No Pavement Damage)

Deeper Root Growth (Greater Stability)

a) Typical Street Tree Configuration b) Permeable Pavement Street Tree Configuration

Figure 1. Permeable Pavement with Street Tree Design Concept

Figure 2 shows the concept design for a permeable pavement and street tree system. Rainfall and runoff infiltrate through the permeable pavement layers and are filtered through the various paving bedding and basecourse layers. The treated stormwater then infiltrates further into the tree root zone in the sub-grade loam beneath the pavement. The increased water and air infiltration promotes healthier and faster growing trees and also results in decreased stormwater volumes and pollution loads downstream. The deeper root zone also provides greater tree stability. As the paving base layers are self-draining and contain no soil particles, tree roots should not seek out water and nutrients in this zone. This should minimise the incidence of pavement surface damage by tree roots. Repairing any surface damage that does occur should also be a simple and cost-effective operation.


Stormwater Infiltrates Through Paving Joints, Filter Media and into Root Zone Below

Pavers (Typically 80mm)

2-5 mm Bedding Aggregate (30 mm Depth)

20-63 mm Sub-base Aggregate

(Depth Varies)

Geofabric Liner

Subgrade Soil

Figure 2. Permeable Pavement with Street Tree Design Concept Experimental Study

A new experimental research project has commenced at the University of the Sunshine Coast (USC) in Queensland, Australia. The research project is sponsored by the Sunshine Coast Regional Council and involves collaboration with researchers at the University of South Australia (UniSA) The aims of this study are to assess and quantify the long-term performance of permeable pavements in reducing stormwater flows and pollution loads, in reducing the incidence of structural damage to pavements by tree roots and in promoting healthier and faster growing trees under typical Australian conditions. The study will also investigate the suitability of various indigenous Australian tree species for use in permeable pavement installations.

The research project at USC was designed to address research needs previously identified by previous investigations. For example, Helliwell and Duncan (cited in Randrup et al., 2001) recommended that fundamental research into the geotechnical and physical conditions that prevent root extension needs to be undertaken. This included the effects that different construction techniques and base materials have on the growth responses of different tree species and an investigation into the interaction between roots and infrastructure, as well as the soil moisture regime under paving systems, for a range of natural and manufactured soils. Randrup et al. (2001) suggested that pavements constructed from porous materials may reduce the incidence of rooting at the interface and the subsequent damage that this can cause.

The field study experimentation at USC has only recently commenced and therefore the experimental results presented in this paper are from the parallel field study currently underway at UniSA. In this study, a total of 18 new street tree-permeable pavement systems were installed in a residential street in Adelaide in September 2009. The study was designed to compare the effects that different paving configurations have on tree health and surrounding soil conditions. All 18 trees planted in the street tree-permeable pavement systems used in this experimental study are Chanticleer pear (Pyrus calleryana ‘Glen’s Form’ Chanticleer) trees. Chanticleer pear was selected for use in the field trials because it is is widely planted by local government authorities in Adelaide and it has proven to have a reliable growth rate under local conditions.


Tree

Control Pavement

Tree

Perm-Level Pavement

Tree

Perm-Swale Pavement

Figure 3. Three Different Pavement Configurations

Three separate paving configurations were used in the field trials, namely, a Perm-Level configuration, a Perm- Swale configuration and a Control configuration. The three different configurations are shown in Figure 3. The Perm-Level Pavement configuration was similar to the pavement structure shown in Figure 2. However, the depth of the 2-5 mm bedding aggregate was 50 mm and the depth of the sub-base aggregate was 100 mm. This gave a total pavement depth of 230 mm (Figure 3) The Perm-Swale Pavement was similar in construction to the Perm-Level configuration except that the subgrade was shaped into a swale and the depth of the sub- base aggregate was 250 mm in the centre of the swale. This gave an overall pavement depth of 380 mm in the centre of the swale. The centre of the swale was one metre in from and parallel to the kerb (Figure 3) The Control Pavement configuration was a typical block paving construction of conventional, impermeable pavers laid on 15 mm of paving sand (Figure 3)

There were six separate Chanticleer pear tree samples for each of the three configurations shown in Figure 3 (18 samples in total) The 18 Chanticleer pear trees were planted in September 2009. The rates of tree growth as well as the soil moisture and oxygen levels were recorded on five different occasions between 15th

September 2009 and 25th February 2011. Measurements of the trees' overall heights, canopy spread, leaf area index and trunk diameters at ground level and elevations of 300mm, 1000mm and 1400mm above ground level were taken. The initial tree height measurement results are presented in this paper.

Tree Cell Trials

Another part of the new research study at USC will investigate and evaluate the performance of a new product called StrataCellTM. This product was developed to promote healthy tree root growth and to provide support and stability to pavements that are constructed above the tree roots. The new product prevents compaction of the soil underneath the pavement by creating a skeletal support structure that keeps pavement loads off the soil under the pavement. This allows unencumbered tree root growth in the uncompacted soil between the StrataCellTM units. A typical StrataCellTM application under pavement is shown in Figure 4.


Figure 4. Typical StrataCellTM Application (http://www.citygreensystems.com)

A number of street tree-permeable pavement systems will be planted in the USC study to evaluate the effect that the StrataCellTM has on tree health and root growth. Tree and root growth will be monitored together with the soil moisture conditions under the pavement. Grabosky et al. (2009) suggested that infiltration and permeability data of permeable pavement systems may be helpful for stormwater management and hydrological design purposes, particularly for estimating water interception in sheet flows from pavements. They also highlighted the importance of providing a water holding reservoir for plant use in transpiration or deep infiltration below the pavement. The experimental results from this study should assist with the identification of these stormwater management design issues.

Results and Discussion

Initial experimental results from 18 new street tree-permeable pavement systems installed in a residential street in Adelaide are shown in Figure 5. The heights of each of the 18 trees were recorded on five different occasions between 15th September 2009 and 25th February 2011. Figure 5 shows the average heights of the six trees in each of the experimental groups at the times of measurement.


http://www.citygreensystems.com/

Ove

rall

Tree

Hei

ght (

m)

2.70

2.50

Control Perm-level Perm-swale

2.30

2.10

1.90

1.70

1.50

15-Sep-09 1-Apr-10 25-Nov-10 25-Jan-11 25-Feb-11

Date of Measurement

Figure 5. Initial Average Tree Height Measurement Results for the Three Groups

Figure 5 shows that trees planted with permeable pavement surrounds generally have a higher growth-rate than trees planted within the impermeable Control Pavements. Of the two permeable pavement groups, it appears that the six trees planted in the Perm-Swale Pavement configurations are growing faster than the trees planted in the Perm-Level pavement configurations. The reasons for this cannot be confirmed at this early stage of the study. As this experimental trial has only been running for less than two years, it is too early to make any long-term predictions on the effects of the different permeable pavements on the growth rates of the trees. It is expected that future results from this study should significantly increase knowledge in this area.

Moisture readings were taken at a variety of depths at three different positions in each of the 18 test pavements. Initial results indicate that the soil directly under the permeable pavement test pavements generally has less moisture than the soil under the Control pavements. This is thought to be due to evaporation through the permeable pavements. This could mean that tree roots that grow under the pavement will suffer during high temperature events due to lack of moisture. This could also mean less pavement damage due to tree root growth. However, further testing is required to verify these hypotheses.

Conclusion

This paper reports on a new experimental research project that has been designed to assess and quantify the long-term performance of permeable pavements in reducing stormwater flows and pollution loads, while reducing the incidence of structural damage to pavements by tree roots and in turn promoting healthier and faster growing trees under typical Australian conditions. Initial experimental results from 18 new street tree- permeable pavement systems have been very promising. Three separate paving configurations were used in the field trials; two pavements were constructed as permeable pavements and the third was constructed as a typical impermeable pavement. The initial results suggest that trees planted with permeable pavement surrounds generally have a higher growth-rate than trees planted within the impermeable control pavements. However, it is still too early to make any long-term predictions on the effects of the different permeable pavements on the growth rates of the trees. It is expected that future results from this study should significantly increase knowledge in this area.

References

Costello L R and Jones K S (2003) Reducing infrastructure damage by tree roots: A compendium of strategies. Western Chapter, Int. Soc. of Arboriculture, Cohasset, CA.

Davis A P (2007) Field performance of bioretention: water quality. Environmental Engineering Science, 24(8), 1048-1064.


Denman L, May P and Breen P (2006) An investigation of the potential to use street trees and their root zone soils to remove nitrogen from urban stormwater, Aust. Journal of Water Resources, 10(3), 303-311.

Grabosky J, Haffner E and Bassuk N (2009) Plant available moisture in stone-soil media for use under pavement while allowing urban tree root growth, Arboriculture & Urban Forestry, 35(5), 271-278.

Hamilton D, Owen W and Davis W (1975) Street tree root problem survey. Univ. of California Coop. Extension Service, Alameda County. 3 pp.

Hatt B E, Fletcher T and Deletic A (2009) Hydrologic and pollutant removal performance of stormwater biofiltration systems at the field scale, Journal of Hydrology, 365(3-4), 310-321.

Islam Md S and Tanaka M (2004) Impacts of pollution on coastal and marine ecosystems including coastal and marine fisheries and approach for management: a review and synthesis. Marine Pollution Bulletin, 48, 624- 649.

Lucke T (2011) Investigation into the sediment accumulation processes that occur in permeable interlocking concrete paving systems in Australia. Proc. of Stormwater Industry Association of Queensland State Conference, Surfers Paradise, Queensland, 25th - 27th May, 2011.

Lucke T and Beecham S (2011) Sediment blockage testing of permeable pavements, Proc. 34th World Congress of the Int. Ass. for Hydro-Environment Engineering and Research (IAHR), Brisbane, Australia, 26 June to 1 July, 2011.

McPherson E G, Simpson J R, Peper PJ and Qingfu X (1999) Benefit-cost analysis of Modesto’s municipal urban forests, Journal of Aboriculture, 25(5), 235–248.

McPherson E G (2000) Expenditures associated with conflicts between street tree root growth and hardscape in California, USA, Journal of Aboriculture, 26(6), 289-297.

McPherson E G and Peper P J (1996) Costs of street tree damage to infrastructure, Journal of Aboriculture, 20, 143-160.

Randrup T B, McPherson E G and Costello L R (2001) A review of tree root conflicts with sidewalks, curbs and roads. Urban Ecosystems, 5, 209-225.

Read J, Fletcher T, Wevill T and Deletic A (2010) Plant traits that enhance pollutant removal from stormwater in biofiltration systems, Int. Journal of Phytoremediation, 12(1), 34-53.

Roberts J, Jackson N and Smith M (2006) Tree roots in the built environment. Vol. 8. Research for Amenity Trees The Stationery Office, London.

Shashua-Bara L and Hoffman M E (2000) Vegetation as a climatic component in the design of an urban street: An empirical model for predicting the cooling effect of urban green areas with trees, Energy and Buildings, 31(3), 221-235.

Smiley T, Calfee L, Fraedrich B, and Smiley E J (2006) Comparison of structural and noncompacted soils for trees surrounded by pavement, Arboriculture and Urban Forestry, 32(4), 164–169.

Tschantz B A and Sacamano P L (1994) Municipal tree management in the United States. Davey Resource Group and Communication Research Associates Report. 72 pp.

* Based on a paper presented at the 12th International Conference on Urban Drainage, Porto Alegre/Brazil, 11- 16 September 2011: Using permeable pavements to promote street tree health, to minimize pavement damage and to reduce stormwater flows by T. Lucke, T. Johnson, S. Beecham, D. Cameron, and G. Moore


Urban Heat Island Mapping in Adelaide

Cäcilia Ewenz1*, John Bennett1, Chris Kent4,Vinodkumar1,2, Huade Guan1,2, Roger Clay3

School of the Environment, Flinders University, Adelaide, South Australia, Australia1*

E-mail: [email protected]

National Centre for Groundwater Research and Training, Adelaide, South Australia, Australia2

School of Chemistry and Physics, Adelaide University, Adelaide, South Australia, Australia3

Bureau of Meteorology , Melbourne, Victoria, Australia4

Abstract

The urban heat island (UHI) effect significantly raises energy requirements for cooling in cities. The resulting additional use of fossil fuels leads to an increase in greenhouse gas (GHG) emissions. Any means of reducing the strength of the UHI has important ramifications for climate and resources. One approach to achieve this is the establishment of urban green spaces, where transpiration by vegetation consumes some of the additional energy that is produced in the UHI.

Due to its unique, carefully planned layout, the City of Adelaide provides a unique setting for studying the effects of nature reserves on the UHI. The Central Business District (CBD) with densely packed commercial buildings is separated from suburbia by an approximately 500 m wide strip of parks and sporting grounds. Uninterrupted time series data was collected over a period of two years, using a dense network of temperature sensors as well as ten comprehensively instrumented stations. Augmented by vehicle traverses, this record was used to establish the spatial and temporal structure of the near-surface thermal climate.

Results show that the intensity of the nocturnal UHI on an individual night in summer was about 3oC with a maximum intensity of 8oC in the early morning, being most pronounced during clear and calm conditions. Open rural landscapes and parkland cooled faster and more than the urban area. The UHI intensity generally showed a minimum early afternoon and a maximum about six hours after sunset. At the parkland sites, diurnal trends were clearer and stronger than in the CBD.

Keywords: temperature network, traverses, green spaces, parkland belt Introduction

The increasing worldwide urbanisation requires urban planners to account for the the anthropogenic urban heat island (UHI) effect, Coutts et al. (2007). A major portion of the world’s greenhouse gas (GHG) emissions is produced by cities and urban areas. The energy used for cooling and heating of buildings accounts for most of these GHG emissions (Grimmond, 2007). The mitigation of the urban heat island effect is achievable through an extension of green areas, open spaces and especially parkland (Yokohari et al., 1997).

The city of Adelaide provides a unique setting for studying the effect of parkland on the UHI. The Central Business District (CBD), roughly 2 km by 2 km square, consists of a region of relatively dense high rise buildings surrounded by an approximately 500 m wide strip of parkland. The parkland is generally covered with short grass and sparse trees. Vinodkumar et al. (2012) suggest that these parkland are probably responsible for mitigating the heat island.



In 2010 Flinders University researchers from the School of the Environment supported by a range of South Australian governmental departments and other local funding agencies established an observational network to capture the spatial and temporal status of the urban temperature field. The setup of the network and a higher resolution traverse project is detailed in chapter 2, while some results from the now more than two years of data are displayed in chapter 3. Concluding remarks are given in chapter 4.

Methodology

The Temperature Network

Between July 2010 and November 2010 a total of 39 locations were equipped with miniature encapsulated temperature sensor/logger units, the Thermochron iButton series DS1921H-F5, DS1921Z-F5 and the DS1922L- F5, manufactured by Maxim Integrated Products (Dallas, Texas). The sensors were mounted in custom-made radiation shields at a height of 4m above ground in Adelaide's Central Business District, the surrounding parkland and the suburbs (blue dots, Fig.1). In addition data from ten stations from the Bureau of Meteorology (BoM) and the Environmental Protection Agency (EPA) could be analysed.

Figure 1. Aerial view of Adelaide CBD and surrounding parkland (Courtesy: Google) with the monitoring locations (blue dots) and the traverse track from 19th to 20th January 2011 (green dashed lines).

The Traverses

In the southern hemisphere summer and autumn 2010/11 a total of four traverses were performed. For the traverses temperatures at heights of 30cm and 1.8m above ground, surface temperature, net-long-wave radiation, sky temperature and temperature and humidity at 1.6m were measured. The sensors were mounted on a pole attached to the roof rack of a car. The tracks were predominantly oriented south-north and east- west through the city centre, the parkland (green dashed lines, Fig.1) and out into the suburbs.

Synoptic Situation

During the traverses a high pressure cell was located east of Tasmania moving away from the continent with a cold front approaching Adelaide from the south-west. Over Adelaide this resulted in weak easterly winds


during the first part of the measurements and hence conditions were favourable for an urban heat island development.

The EPA monitoring weather station Netley, located close to the Adelaide airport, but on the city site in the suburb of Netley, exhibits a change at approximately 11:30pm, the wind speed dropped and the winds turned westerly. A modification effect on the development of the UHI was not found.

Figure 2. Temperature. The isolines show temperature derived from the iButton network at 20th January 2011 5:30 am. Displayed are the city average (red dots), the parkland average (yellow dots), Currie St (blue diamonds) and Parkland South (green diamonds).

Data Analysis

The traverse data as well as the iButton data were adjusted for known calibration errors. Before the iButtons were deployed in the field and after recovering the buttons a correlation study was performed against a well calibrated sensor in order to establish the differences between each sensor (measurements have to be very accurate to account for small changes found in temperature in the urban environment) and to verify the stability of the measurements over time. Temperature, humidity and radiation traverse data were adjusted in time to GPS time.

The traverse instrumentation was mounted in front of the car, in order to avoid a heat effect of the car. To reduce the effect of cars driving in front, low car speeds were rejected from the data set. Travel times and locations were evaluated to find coinciding data from the fixed network.

Results and Discussion

Diurnal Cycle in CBD and Parkland

On the 19th/20th January 2011, the temperature difference between the CBD and the surrounding parkland (Fig.2) is greatest in the early morning between 4:30 am and 6 am. The difference between individual stations e.g. Currie St, which is surrounded by the highest buildings in the Adelaide CBD and the Southern Parkland (Fig.2) reached up to 8°C during this particular night.

Fig.3 displays the spatial distribution of the temperature, acquired from the iButton network. Here the highest temperatures were found where the lowest sky-view factor exists. The green areas, parkland and Victoria Square (a green space in the centre of the CBD) exhibit lower temperatures (Fig.3).


Figure 3. Aerial view of Adelaide CBD and surrounding parkland (Courtesy: Google). The isolines show temperature derived from the iButton network at 20th January 2011 5:30 am.

The traverse of the 19th/20th January 2011

Over a six hour period during the night of the 19th to the 20th of January 2011 a number of north-south and east-west traverses of the CBD were collected. Preliminary analysis shows a good agreement between the traverse data and coinciding network data. Fig. 4 exhibits a short, 4 minute long, track from North Adelaide towards Victoria Square, crossing the Torrens River.

Figure 4. Temperatur

e in 1.8 m from the traverse data set. The track starts at Victoria Square (left) and finishes in North Adelaide (right).


The temperature at about 12:00 am increases towards the CBD centre where the highest buildings are, decreases towards the Torrens and exhibits an increase into North Adelaide. This is also visible at 5:30 am in Fig.3 with higher temperatures in the CBD, a local minimum along the Torrens River and a local maximum again in North Adelaide. Fig.5 does show the maximum in the CBD but does not reveal the second maximum in North Adelaide. Although the lower temperatures further north were represented in the traverse data.

Figure 5. Aerial view of Adelaide CBD and surrounding parkland (Courtesy: Google). The isolines show temperature derived from the iButton network at 20th January 2011 12:00 am.

Conclusion

The temperature network in Adelaide's CBD can clearly exhibit the nocturnal urban heat island. The area in the city with highest buildings and hence largest heat storage capacity does reveal higher temperatures during low wind and clear sky conditions.

Traverses through the parkland and city area display an even larger variation in temperature than the fixed network can resolve. Local minima, e.g. the Torrens River, are generally not represented well in the fixed network but were analysed from the traverse data.

From Figures 3 and 5 it is clear that even small open spaces like Victoria Square mitigate the heat island. This square is located in the centre of the CBD, but generally displays a local minimum in the temperature data.

The iButton temperature network which is running for approximately two years. A nocturnal urban heat island develops in most of the weak wind and clear sky conditions with winter and summer differences between city and parkland off similar magnitude [4]. While daytime temperatures in summer and winter in CBD and parkland reveal significant climatic distinctions.


Acknowledgements

Funding was provided by South Australian departments and some local governmental organisations, namely DENR, ACC, DPC, DPLG, ETSA. The EPA and the BoM provided data from their local station network and the University of Adelaide and Flinders University provided support and funding. Graeme Hopkins, Craig Simmons and Peter Schwerdtfeger contributed at the early stage of the project . Chris Kent, Chuanyu Zhu and Robert Andrew assisted with the field data collection.

References

Coutts A M, Beringer J, Tapper N J (2007) Impact of increasing urban density on local climate: spatial and temporal variations in the surface energy balance in Melbourne, Australia. J. Appl. Meteor. Climatol., 46, 477– 493.

Grimmond S (2007) Urbanization and global environmental change: Local effects of urban warming. The Geographical Journal, 173, 83−88 Maxim Integrated Products, Inc. 160 Rio Robles San Jose, CA 95134 USA http://www.maxim-ic.com/products/ibutton/ [30 June 2012]

Vinodkumar H, Guan C T, Simmons J M, Bennett C M, Ewenz C, Kent (2012, submitted). Influence of parks on urban environment: Observational and numerical study over Adelaide, Australia.

Yokohari M, Brown R D, Kato Y, Yamamoto S (1997) The cooling effect of paddy fields on summertime air temperature in residential Tokyo, Japan. Landscape Urban Plan, 53, 17 – 27.


http://www.maxim-ic.com/products/ibutton/

“Yeronga Memorial Park Project”

Andrew Ensbey Brisbane City Council

Introduction

“Thank you so much. You have no idea what this means to our family” (Yeronga resident and relative of one of the 97 serviceman from the district represented by a plaque in Honour Avenue).

In fact, this serviceman was one of three brothers from the same family who each lost their lives in World War 1. For their living relatives, their memory, each represented by a tree in an avenue in a park, is a very real reminder of the tragedy of war and the lingering impact on families since.

This is what the Yeronga Memorial Park Project is really about. It was never about spending an allotted amount of capital funds in xyz park in xyz financial year. What a colossal waste of a privilege that would be.

The purpose of this paper is to provide a snapshot of the key learnings from this project that enabled it to chart a way from difficult beginnings to having someone express the quote given above. In doing so, my hope is to inspire other councils and authorities to invest in similar projects that make a real difference to real Australian families.

Context

Yeronga Memorial Park is a large (23ha) park in Brisbane’s inner south, serving a range of recreational and sporting needs of the community. It also happens to contain a number of memorial features, including two significant tree-lined avenues planted at the end of World War 1.

The whole park was placed on the Queensland Heritage Register in 2005 to recognise a number of attributes including:

• the pattern of Queensland's history, being a recreation reserve established in 1882, and later a memorial park from 1917

• the process of grieving that was occurring across Stephens Shire, Queensland and Australia at that time evidenced via the memorial avenue, gates and pavilion

• the layout and characteristics of a public park, since 1882 and a war memorial since 1917 the layout and elements of the park

• its significant aesthetic values • its social significance via a strong and ongoing association with the local community.

In 2010, Council set aside $500,000 to deliver some improvements to the park, with the scope to be determined in consultation with the local community, including a specially formed Community Advisory Group (CAG). Some of the members of the CAG were also part of a community group with strong interest in the park, known as the Friends of Yeronga Memorial Park (FoYMP). Allowing the community to influence the scope of a project can often lead to different outcomes than those originally expected but nonetheless is a genuine way


to create ownership of a place to maximise Council’s investment. In this case, the CAG made Council acutely aware of what they wished the focus of the project to be, and it wasn’t for recreational improvements.

The park did not have a Conservation Management Plan in place so it was felt that without one the project could not proceed. Whilst Council did not believe one was completely necessary at the time, it turned out to be a contributing success to the overall project. As an added bonus, the exercise was later recognised by the Queensland Heritage Council as a leading example of heritage conservation. But it was not all roses at the beginning…..

Difficult beginnings

The project could have very easily not got off the ground. It certainly had its fair share of hurdles including:

• Qld regulatory big brother – State legislation required every change to the park to follow a highly scrutinised exemption certificate process

• The historic record of the park was known to be incomplete • A number of myths were held by people about historic details • Some CAG members were untrusting that Council would listen to their views • The general public were disengaged due to past inaction in the park and a perception that the vocal

minority would always get their way • The two primary WW1 avenues were incomplete and in struggling condition • The park had little capital spends or maintenance in the recent past due to continual conflict from a

vocal minority • The timing for the project was during the lead up to a local government election • The local press tended toward provocative representations of project information • There was conflict in the community about recreational and conservation priorities • Some existing memorial trees were a public safety hazard • Unrealistic timeframe set for completion

All of these issues needed careful consideration if the project was going to succeed, and it needed a robust process.

Project Process

I am a firm believer in good project management practises. Without them it is difficult to plot a project’s future through the maze of issues that will confront it. The following is an outline of the key steps in sequence as applied to this project.

Establish governance model – Decide right upfront who is going to call the shots. Who will play what role? What approvals are needed? Will the community be given power to decide or advise?

Develop a communication plan – Plan how all stakeholders will be involved. What are their key interest areas? What is the goal of the project? What are the key messages?

Research and detective work – Find out what you don’t know. Ask questions. Develop a sound base of knowledge supported by evidence on which to make future project decisions.

Develop a conservation framework – Outline how the body of knowledge and evidence will be applied to the site. What will be made prominent? What will be understated? What is the justification?

Design options – develop options for how the funding can be spent. Consider different points of view. Consider impacts on future operational costs.

Prioritise the works – Seek stakeholder feedback to choose an order of importance. What must be done? What can wait? What dependencies exist? Factor in a contingency figure.

Implementation – Deliver the agreed scope of works. Don’t deviate. Start when you say you will.


Dedicate the new work – Formally celebrate the completion of the work. Re-confirm its meaning. Invite stakeholder participation.

Provide interpretive opportunities – Provide opportunities for site users to understand points of significance. Consider how people take in information. Be interactive as much as possible.

Ongoing maintenance investment – Look after what was established. People will be watching. This is the big chance to proof you meant it.

So what did this process deliver for the Yeronga Memorial Park project? Achievements

After the successful establishment of the Land and Conservation Management Plan for the park, a range of recreational and conservation improvements were developed, and community feedback was sought. A balanced approach was decided on which led to some quality recreational infrastructure being installed, along with the following key conservation outcomes for the project:

Restoration of Honour Avenue – Consolidation of the memorial planting forming the avenue including removing unhealthy and unsafe trees and those of wrong species, planting of new Weeping Fig trees, formative cathedral pruning, and mass-mulching to improve soil condition.

Replacement of Honour Avenue name plaques – Re-establishment of lost, damaged, and buried name plaques representing the 97 servicemen from the district that lost their lives in World War 1. Historical research uncovered an original plan showing the original order of placement of the names beneath the trees and this was carefully followed.

Restoration of Anzac Parade – Consolidation of the memorial planning forming the avenue including removing unhealthy trees and those park trees that interfered with the avenue, planting new palm trees, and mass-mulching to improve soil condition.

Memorial gates restoration – Refurbishment of the two original sets of memorial gates marking the two main park entrances, including the entrance to Honour Avenue.

Cenotaph maintenance – Restoration of the structure’s metalwork. (The stonework was restored two years prior.)

Interpretive signage – Installation of a suite of interpretive signage that invites park users to appreciate the historical, cultural, and environmental significance of the park.

The conservation works were completed just prior to the 2012 Anzac Day service. I could not imagine a more fitting setting. Council took a back seat and the local RSL Sub Branch arranged the proceedings, to ensure the meaning of the works was given upmost priority. Standing side by side during the playing of Reveille with some of the most vocal stakeholders at the beginning of the project, there was no feeling of resentment, for we all knew the purpose of this moment was far greater than any of our efforts.

So, what are the key learnings to take from this project that I consider played a part in its success? Here they are in a nutshell, and in no particular order.


Key Project Learnings

Know your funding strategy upfront – there is little point commencing a project that you cannot afford or at least identify a possible funding stream for. Stakeholder expectations can get away on you.

Consider whole-of-life costs – Funding the capital project is just the beginning and is often the cheapest part of the whole-of-life cost of the project. Consider as an example the cost of maintain one tree for 100 years compared to the cost of planting it in the first place……

Professional advice can be worth every cent – For those critical parts of the project that everything hinges on, do it right the first time, and if you don’t know how, seek help. Case in point - professional historians are well worth their fee.

No egos and have respect for all opinions – Don’t go into a project thinking you know better than others because there is a very good chance you don’t, and it will be proved to you at the worst possible moment. Listen to others and stay teachable.

You don’t know what you don’t know – Don’t go into this kind of project thinking you have it fully scoped. Be open-minded and prepared for some things to come out of left field.

These are more than just capital projects – The project leader really needs to appreciate the meaning at the crux of the initiative. This needs to sink in from the beginning. If they don’t get it, move them on.

Be transparent with information – There is no point hiding what you know, particularly when it comes to uncovering history. Get it out in the open. This builds trust and helps contain conspiracies.

Have a robust rational for change/decisions – If you cannot back it up with sound evidence or rationale, don’t run with it. These things have a habit of coming back to bite you when you least expect it.

Make time for people – After all, that is what these projects are about. Find out who knows what and listen to them. Even the antagonists often have useful points to consider.

Allow time for changes to sink in – Nobody likes change, especially if it’s happening to them. If something is going to shake someone’s tree, you have to make time for things to settle. Rushing things will cause delays in the long run.

Maintain one point of contact – Clear communication is the key to managing expectations so it is best to channel this through one person if possible. This is a great strategy for rumour control.

Staging a project is not a failure – Not completing a project by running out of money or resources is. If the outcome has to be staged, do it, and communicate the rationale clearly.

Attention to detail – A project can quickly be tarnished by a stuff-up. Always check the details and triple check spelling and references. Don’t rely on Spellcheck; it is waiting to make a fool out of you.

Celebrate success and achievements – Hard work pays off so take the time to enjoy the wins. Be sure to involve all those who had input into the project.


Conclusion

It is a privilege to be able to contribute to the lead up to the centenary of Anzac in 2015 and Brisbane City Council is proud to be working toward the restoration of its memorial avenues and plantings as we approach this milestone. Since 2007, Council has completed a number of different scale projects across the city including one at Tennyson, Graceville, Toowong, Bulimba, Chermside, Balmoral, and Tarragindi. Yeronga Memorial Park now joins this list as we continue to plan for further projects to be implemented.

REFERENCES:

Brisbane City Council. 2007. Avenues of Honour – Research Report.

Brisbane City Council. 2011. Yeronga Memorial Park - Land and Conservation Management Plan.


The Burnside Village Tree – A Case Study of Construction and Tree Protection

Marcus Lodge

Arborman Tree Solutions Introduction Burnside Village is a relatively major suburban shopping centre servicing the eastern suburbs of Adelaide. The owners of the shopping centre have tried to maintain the ‘village’ feel of the shopping centre through various developments over the past 20-30 years. A major part of this has been the retention of a number of mature eucalypts within and around the car parking area; to the point that when looking at the next stage of the development there was an overriding requirement to retain as many trees as possible. One of the trees, a River Red Gum, was located in an existing driveway/parking area between two separate sections of the shopping centre; this tree was particularly important to the owners and as such they started the design process with the premise that this tree be retained and incorporated within the new shopping area.

In order to retain the tree the owners employed us to assess the tree and determine how much protection was required to minimise the impact of any potential development around the tree. Assessments were undertaken in 2007 and a Tree Protection Zone (TPZ) of 11 metres in radius was calculated to be appropriate for this tree in this situation. The owners then used this information to assist in designing a new complex around the tree.

In late 2008 to early 2009 the preliminary design was put together with the tree to be centred in a new mall area with shops on three sides and the main entrance on the fourth side. The tree was to be retained in an open alfresco type area with its crown extending through and above the roof. Due to the need for increased car parking the area around the tree’s TPZ was to be excavated to allow for under croft parking; effectively this was akin to putting the tree in a large pot. Whilst there were some obvious challenges these preliminary designs looked very exciting and promised a good result for both the shopping centre and the tree.


Over the next twelve months plans and method statements were put in place to remove the existing infrastructure, including buildings, services and pavement, and manage the canopy to ensure minimum contact with construction equipment and in the longer term the proposed building. A tree protection plan was also put in place to ensure both the root zone and canopy were protected during the construction phase.

In early 2010 the final plan was completed and there were a number of changes to the preliminary plans that both impacted directly on the tree and on a number of the tree protection measures that had been put into the tree protection plan. Some of the changes were:

• Suspending a deck over the majority of the TPZ which involved four piers being sunk into the root zone; and

• Installation of an air vent from the under croft parking within the root zone and below the proposed deck; and

• Installation of other services to supply water and electricity to water features and lights around the tree; and most importantly

• The introduction of a roof above the tree to allow the deck to be used all year as an alfresco type area.

Obviously these changes meant a rethink in a number of areas and some investigation/research into the potential impacts of putting a glass roof above the tree. In hind sight this was an opportunity to reconsider the whole scenario more thoroughly as the level of impact had reached a point where the tree was potentially going to respond poorly. Having said that the reality was that glass is available that allows for plants to grow well beneath it and as such this wasn’t seen as a factor that would prevent the successful completion of the project. The issues could be dealt with through the tree protection zone method statements and management protocols. With construction due to start almost immediately the first phases of the tree protection and management plan and then implemented on an as appropriate basis. There were a number of issues associated with the construction process:-

• Torrential rain at important times delaying activities on the site and within the TPZ. • Torrential rain washing building waste into the TPZ causing contamination of the area. • Greater than anticipated requirements for support piers within the TPZ. • Enclosed scaffolding around the tree for the installation of the roof and glass above and adjacent

to the tree. • Additional service installation below the deck. • No allowance for water to be supplied to the irrigation system below the deck. • Various other relatively minor construction activities.

The tree has shown signs of stress throughout the period since the roof was installed. A number of potential causes were considered including the below:

• The roof; shouldn’t be, the glass was requested to allow the full spectrum of light through to the tree to ensure photosynthesis was not inhibited.

• Lack of water; moisture tests show the irrigation is providing adequate water and the soil moisture is stable.

• Lack of rain; without rain falling on the crown the leaves may be getting dirty and potentially being affected to the point where they are not photosynthesising to their capacity.

• Nutrient levels; tests again show the nutrient levels are about right and with the amelioration this should improve further.

• Lack of wind; possibly an issue with little to no wind contacting the lower crown where the majority of dead leaves were being retained.

• Air quality; possibly - air conditioning has been installed and dry air was being directed toward the crown.

Testing With the assistance of the University of Western Australia and Murdoch University we were able to undertake a number of tests within the crown.


These included testing light levels at different times of the day and monitoring humidity, temperature and leaf turgidity (water content) over a six week period.

The test results gave us the following information:

1. The light levels were at the lowest point for photosynthesis to occur and given River Red Gum is a relatively high light user it appears leaves that were unable to be productive were/are being shed.

2. The humidity is so low, dry air, in the crown that for the majority of the day the leaf stomata were effectively closed; this further limits both the tree’s ability to take up water and therefore to photosynthesise.

3. There is increased insect and fungal activity on the leaves which is likely to be related to the low humidity.

4. Water whilst available is not being taken up due to the lack of photosynthetic activity and the low humidity causing the stomata to close.

Obvious thinning and dead leave retention particularly in the lower canopy.


Where to from here? The Burnside Village management have committed to implementing a number of strategies to enhance the tree’s environment and to minimise the identified issues. • Modification of the air conditioning system to prevent dry, heated or cooled, air being directed onto the

tree. • Installation of a misting system to increase the humidity in the crown to the point where stomata

activity is normalised. • Installation of a full spectrum lighting system to increase the usable light available for photosynthesis. • Crown management to remove sections that are not going to recover and maximise the potential for

the remaining branches to improve their foliage cover. • Ongoing monitoring and treatment of soil moisture and nutrient levels to maintain the tree’s

requirements. Conclusion The tree has undergone radical changes over the last 24-36 months and is still adapting to its new environment. Management processes are in place to improve the tree’s environment and there is a strong commitment from Burnside Village to do the best by the tree.

The long term success or failure of this tree will depend on how well we monitor it and assist it to adapt to its new environment.

The tree potentially has a good future however this is an ongoing project and only time will tell as to its long term success.


Myrtle Rust - Addressing the Challenge

Grant Dalwood Nursery & Garden Industry SA Industry Development Officer

Myrtle Rust in the Australian Nursery Industry In April 2010 Myrtle rust was detected in Australia on the Central Coast of New South Wales (NSW). A national response was agreed to under the Emergency Plant Pest Response Deed (EPPRD) and a comprehensive surveillance and management program was initiated within NSW.

Myrtle Rust (Uredo rangelii) Myrtle rust (Uredo rangelii), a plant fungal disease native to South America, is a member of the fungal complex known as the guava rust (Puccinia psidii) group. Based on experiences in Australia between April 2010 and February 2012, information from New South Wales and Queensland, shows myrtle rust has an expanding host range currently infecting approximately 200 species from 41 genera or approximately 46% of known genera (Myrtaceae) in Australia. The pathogen infects young, actively growing, emerging leaves, buds, flowers, green stems, fruit and shoots of plants within the Myrtaceae family. In Queensland to date the most severe infections of the disease have been recorded on

By November 2010 more than 140 infected premises had been identified across NSW with the first detections outside horticultural industries being recorded in state forests and nature reserves. The initial detections of the disease in Queensland occurred in December 2010 in the south east of the state with further detections noted in Cairns, Townsville, Rockhampton, Gladstone and Hervey Bay during 2011. The most recent detections outside of NSW and Qld occurred in Victoria during the January 2012 with more than 60 sites around Melbourne infected by mid 2012.

On December 22nd 2010 the Myrtle Rust National Management Group agreed the disease was not technically feasible to eradicate in New South Wales and cancelled the Myrtle Rust Response Plan previously enacted under the EPPRD. Due to the impact the disease could have across Australia it was further agreed to implement a structured management plan to limit the establishment of the pathogen within industries and the natural environment. The federal government, through the Department of Agriculture Fisheries & Forestry (DAFF), established the Myrtle Rust Coordination Group to plan the investment of $1.5 million of research funding across six key themes:

National Transition to Management Plan:

Theme 1: Coordination and communication Theme 2: Immediate disease management Theme 3: Taxonomy and identity of the pathogen Theme 4: Potential impact and distribution Theme 5: Chemical control options Theme 6: Resistance breeding options

The development of this industry specific Myrtle Rust Management Plan, by the Australian Nursery Industry, is in direct response to the agreed national position in which the industry participated in developing. As a professional and responsible industry it is appropriate that all growers, wholesalers and retailers apply the relevant strategies to manage myrtle rust as described in this plan.

Myrtle rust (Uredo rangelii) has the potential to infect all myrtaceous plants in both our built (gardens & landscape) and natural environments plus a range of industries (nursery production, timber, cut flower, etc) more likely along the coastline of Australia due to suitable environmental conditions. Under threat from this disease, if it becomes widely established, are a number of identified threatened native plant species across Australia plus a number of endangered wildlife habitat(s) that could have a major impact on our natural biodiversity.


Myrtle rust may infect plants under a wide range of environmental conditions, however infection rates may be heightened when the following conditions are present:

- Soft new growth/tissue - High humidity - Free water on plant surfaces for 6 hours or more - Night temperatures (optimal) within 15 - 25:C however as low as 10°C (CSIRO. 2012) - Low light conditions including darkness (minimum of 8 hours) after spore contact can increase

germination success - Life cycle can be as short as 10 – 14 days (spore to spore)

Myrtle rust has the ability to complete its entire lifecycle on a single host plant. Myrtle rust initially causes light infection on young leaves and new shoots which can appear as yellow flecks. Lesions expand radially and can coalesce (join) with age and susceptible tissue shrivels and dies. Secondary infections within the plant can occur within days of the first pustules appearing. Repeat infection may result in plant death, although this is likely to vary from species to species.

It is possible that as this disease establishes in Australia the host range may grow to include many of the internationally recorded plant species infected by guava rust. The nursery industry must consider all myrtaceous species as potential hosts of myrtle rust. Note: Guava rust (Puccinia psidii) is also known as eucalyptus rust and has caused heavy crop losses in the Brazilian hardwood industry through the decimation of planted Eucalyptus seedlings in the field. For identification purposes myrtle rust and guava rust are visually and symptomatically identical therefore identification tools are interchangeable.

The general symptoms of myrtle rust/guava rust include: (Myrtle rust generally attacks soft new growth including leaf surfaces, shoots, buds, flowers, young green stems and fruit)

1) Tiny, raised spots or pustules with possible yellow flecking 2) Small purple or red brown flecks with a faint chlorotic (yellow) halo on leaf surfaces 3) Large purple or red/brown lesions as a result of flecks coalescing 4) Purple or red/brown lesions and bright yellow rust pustules producing spores 5) Bright yellow rust pustules producing spores on underside of the leaf (young infection) 6) Bright yellow rust pustules producing spores on both sides of the leaf (mature infection) 7) Small and large necrotic lesions, with possible purple margins, and leaf distortion (twisting) 8) Older lesions can contain brown/grey rust pustules that no longer produce yellow spores on the

lesions

Fungicide Treatment For the treatment of plants (Myrtaceae family) the industry has access to an Emergency Permit (PER12156) that allows a range of fungicides to be applied for the management of myrtle rust. Therefore if you intend to treat plants with a fungicide you must have a copy of this permit on-site and you must use the application rates as outlined in the permit.

On-site Biosecurity Actions Businesses in all states and territories, production, wholesale and retail, maintain the highest plant health standards to ensure this disease is either suppressed and managed or not introduced. Any business purchasing, or has sourced, myrtle rust host plant material from an outside source must survey their stock to ensure freedom from the disease. Other businesses with host plants are advised to maintain a structured monitoring program (weekly) to ensure they remain free of the disease or detect infects early and apply a suitable management strategy.

Myrtle rust can move across the landscape and within a production system by:

- Vegetative material (alive or dead) - Contaminated plant containers (pots, trays, etc) - Air movement of spores (dry spores can move great distances – many kilometres)


- Human assisted movement (spores on clothing/vehicles/containers/etc) - Water splash from rain and irrigation (wet spores are difficult to move by air) - Animals both native and domestic (possums, cats, birds, insects, etc)

Production Nursery (including propagation)

- Ensure a high standard of awareness of the disease at all staff levels - Advise staff to avoid any plant contact prior to arriving at work & wear clean clothes - Have on-site disease (myrtle rust/guava rust) identification information for all staff - Train staff on disease identification & good hygiene practices (see State biosecurity websites and

Nursery Paper December 2004 Issue No: 11 at www.ngia.com.au ) - Disinfest all equipment/vehicles that move off-site and return to operate within the production area - Limit the access of people (visitors & staff) to your production areas - Implement a hygiene protocol for essential visitors (contractors, etc) to production areas including

awareness of previous work sites, inspection of clothing/tools, etc and if required provide disposable overalls while on-site

- Restrict all non-business vehicles from entry to production areas, disinfest if required on-site – APVMA Permit: PER10535

- Remove myrtaceous plants from driveways and carparks or prune to avoid possible visitor contact - Consolidate all myrtaceous plant species within a defined area on-site away from native or landscape

planted myrtaceous plant species and avoid direct exposure (buffer) to the prevailing winds of the season

- Allocate specific staff to manage all myrtaceous species - Source myrtaceous plant material from known professional growers (e.g. NIASA Accredited) - Request suppliers of myrtaceous plant material provide evidence that they are adhering to the Myrtle

Rust Management Plan - Maintain a quarantine area for imported nursery stock - Inspect (at quarantine area) and treat (curative fungicide) imported myrtaceous species prior to

incorporating into growing areas (7 days and re-inspect). It is recommend this be applied irrespective of the source

- Monitor all myrtaceous plant species weekly across growing areas for disease symptoms (particularly inspect areas of crop that have high humidity e.g. centre of batch and on the side exposed to prevailing winds)

- Ensure growing areas remain free of all waste vegetative material - Increase plant spacing where appropriate to reduce humidity levels within crops

Implement a fortnightly fungicide treatment program across all myrtaceous plants (see recommended program(s) Section 5.2)

- Treat with a disinfectant (e.g. copper) the growing area upon the completion of the crop growing cycle before placing a new crop down on the production bed

- Dispose of all extraneous vegetative plant material from crop management such as pruning, detailing or from natural desiccation via bulk waste, composting or deep burial

- Assess irrigation system and timing to ensure plant surfaces are dry within a short period (less than 6 hours) after irrigation.

- Avoid irrigating late afternoon which allows water to sit on surfaces for periods of 6 hours or more during the night. Consider installing drip/capillary or other under canopy irrigation system to myrtaceous plant species

- Access industry guidelines such as NIASA and BioSecure HACCP for guidance in developing monitoring/surveillance/inspection programs and recording templates.

Propagation

- Maintain high health practices in propagation (surface/implements/equipment disinfestation, staff hygiene, etc)

Infected Crop Management


http://www.ngia.com.au/

Crops found to be infected with myrtle rust can be managed by a range of options depending on part or entire batch infections and preferred treatment method.

Despatch Sampling Process Interstate Movement Controls Since early May 2010 there have been various movement controls put in place by a number of state and territory plant health agencies to manage the risks associated with the movement of host plant material.

Interstate Certification Assurance (ICA) Arrangement Biosecurity Queensland (BQ) has developed the Interstate Certification Assurance arrangement for myrtle rust (ICA 42 Nursery Freedom, Treatment And Inspection For Myrtle Rust) and is available to Queensland and New South Wales and Victorian production nurseries for access to South Australia and Northern Territory markets.

Interstate Movement Controls Since early May 2010 there have been various movement controls put in place by a number of state and territory plant health agencies to manage the risks associated with the movement of host plant material.

Myrtle rust is a notifiable pathogen in all Australian jurisdictions, where currently no positive detections have been recorded, requiring any detection of the disease be reported to the relevant state or territory biosecurity agency within 24 – 48 hours.

The challenges are many and ultimately all of Australia will have to live with Myrtle Rust to what ever degree a locations climatic conditions and vegetation are.

We as an entire Industry have to manage and learn to control the problem from both a business and flora point of view! Research is vital as is the entire industry taking responsibility for their actions regarding propagation, growing, planting, sales and movement of Myrtaceae plants. If we don’t then arguably Australia’s most important genera will face enormous difficulty in surviving in its current known form.

Thankyou for your attention

Grant Dalwood NGISA Industry Development 505 Fullarton Rd Netherby SA 5062 [email protected]

ref: Nursery & Garden Industry Australia Myrtle Rust Management Plan 2012 (Uredo rangelii) www.ngia.com.au/Section?Action=View&Section_id=527&Highlight1=myrtle rust&Highlight2=myrtle rust



http://www.ngia.com.au/Section?Action=View&Section_id=527&Highlight1=myrtle

Tree protection laws in Australian states and territories

Michelle Lensink

Introduction The laws which protect vegetation from damage and clearance across states and territories in Australia vary considerably. What they share in common is that as Acts of Parliament (and Regulations) they are promulgated by state and territory parliaments.

At the start of my research, I thought that most states and territories had blanket laws aimed at protecting trees on private land. In fact, most don’t! Even where they do exist, they rely heavily on local government to administer them.

I did not intend for this report to canvas conservation laws, however for the sake of completeness they need to be included, and form an important part of protecting ecological communities in the so-called “public estate” (that is, our system of national parks and reserves) and on private property. In those jurisdictions without state or local government tree protection laws, the only protection for trees generally relies on conservation legislation.

A quick word on Acts versus Regulations. Regulations (or “Regs”) are known as “subordinate legislation” because they rely on the existence of an Act of Parliament, which is considered a superior instrument. An Act must pass both houses of parliament (not relevant in Queensland, the ACT or NT) and therefore requires the political support of both houses of parliament (not always a simple process because government often don’t control their upper houses – they rely on the support of the opposition or minor parties and independent Members). Individual clauses in a Bill (the precursor to an Act) can be amended by either house of parliament; regulations cannot, they can only be “disallowed”, in which Parliament can vote them down without amending them. The terms “legislation”, “regulations”, “laws” etc are often used interchangeably, even though their precise meanings are more nuanced.

Hierarchy - categories of vegetation and levels of protection Vegetation and tree protection laws can be categorised based on the aims of the legislation, the location of the plant species and whether it is part of an indigenous/native ecological community, whether it may have heritage or a variety of other attributes, such as amenity, girth size, canopy size, height etc.

The highest level of protection is provided for plants located in national parks (“the public estate”). With so much of Australia’s landscape having been cleared since European settlement, conservation parks provide a refuge for ecological communities through protection of native flora and fauna. These sets of laws aim to prevent human interference with the balance of the natural landscape by prohibiting the taking of any plants or animals from their environment; while simultaneously seeking to exclude pest species. The sale of flora and fauna is illegal and legitimate handling is enabled through permit systems, for instance for native species nurseries or wildlife rescue operations. There are significant penalties for breaking these laws and parks have their own police force in park rangers to enforce the laws. All states and territories have parks laws.

The next level is protection of native vegetation on private land, with similar goals of preserving remnant habitats to conserve biodiversity. These laws protect indigenous tree species, and also shrubs and bushes and to a lesser extent, grasses, sedges etc (everything below the canopy). Native vegetation laws have common themes across states and territories, and prohibit pruning, burning or destruction without the permission of the relevant state or territory authority. They generally apply only in rural areas, excluding capital cities and other parts which are zoned as residential, townships, industrial etc. There are significant penalties for breaking these laws. All states and territories have such laws, with the exception of the Northern Territory.

Indigenous plant species may also receive additional protection through s266B of the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 when considered threatened, endangered or vulnerable.


Other laws which may protect trees are available through heritage and/or Aboriginal heritage legislation. The common themes of these acts is that there is a State-based statutory authority which assesses and administers the nomination and registration process, with penalties for damage and destruction of the heritage “item”/”area”/”place”. Not all of the relevant Acts specifically include a reference to “tree” or “trees” in being an item or forming part of an area or place however this does not seem to affect whether trees can be listed or not.

There are also laws in some jurisdictions which focus on “significant” trees (not just native species), heritage protection of trees (again not just native) and indigenous trees.

Only two jurisdictions have specific statutes to provide blanket protection to native and non-native tree species on private land – the ACT and SA. Other jurisdictions enable local government through their relevant planning Acts to create registers, lists, “overlays” (Victoria), or by-laws, “local laws” or local planning instruments to specifically provide for the protection of trees in the landscape.

Common themes in tree laws across Australia, regardless of whether they are a State statute or a local government instrument, include:

• declared pest species are exempt from protection, and • pruning of protected trees is permitted if it is for maintenance (or in the best

interests of the tree). Criteria to determine which trees should be protected vary greatly. Many councils have registers of significant trees, to which members of the public may make nominations.

ACT Tree Protection Act 2005 The hybrid jurisdiction of the ACT has the most detailed 100-page tree-specific legislation. The objects section of the Act states that it exists to protect both individual trees and the urban forest, as well as to promote community appreciation of trees.

The Act recognises trees under two sets of circumstances which provide similar levels of protection:

1. “Registered” trees which have been placed on the register because of their individual importance. A list and description of regulated trees can be found at: http://www.tams.act.gov.au/live/environment/treeprotection/acttreeregister/regist ered_trees The registration process is similar to heritage nomination.

2. “Regulated” trees, are those trees (regardless of species, unless a declared pest) which meet certain criteria and are located in a declared Tree Management Precinct (which is most of Canberra, according to http://www.legislation.act.gov.au/ni/2010- 414/ ): • are 12 or more metres high; • have a trunk with a circumference of 1.5 metres or more, one metre from the

ground; • have two or more trunks and the sum of their individual circumferences at 1 m

above ground is 1.5 m or more; or • have a canopy 12 m or more wide.

Trees which fall into one of these categories cannot be damaged without approval. The definition of damage includes: killing, destroying, felling, removing, ring barking, lopping, pollarding, poisoning, major pruning, or anything else that causes the tree to die, reduces its expected life span or significantly and adversely affects the tree’s health.

“Minor pruning” is permitted without approval. For regulated trees minor pruning means pruning (other than lopping or pollarding) performed in accordance with the Australian Standard on Pruning, AS 4373, that does


http://www.tams.act.gov.au/live/environment/treeprotection/acttreeregister/registered_trees

http://www.tams.act.gov.au/live/environment/treeprotection/acttreeregister/registered_trees

http://www.legislation.act.gov.au/ni/2010-414/

http://www.legislation.act.gov.au/ni/2010-414/

not affect the general appearance of the tree or if it is a fruit tree, if it is done in accordance with the Standard and is done for fruit production [s.13(2)(b)].

For registered trees, minor pruning means pruning (other than lopping or pollarding) conducted in accordance with AS 4373 that is limited to:

• removing deadwood; • removing limbs with of a diameter of 50 mm or less; or • the first pruning of the tree in the calendar year, which affects less than 10 per

cent of the canopy and does not change the overall shape of the canopy.

Uniquely, certain groundwork is prohibited without approval within the tree protection zone (deemed to be under the canopy of the tree, within a two metre radius out from the canopy, within a four metre radius surrounding the trunk as measured at one metre above natural ground level or as defined in a tree management plan for the tree). Prohibited activities include:

• changing the soil level (except for the preparation of garden beds, the planting of trees and shrubs or other cultivation for horticultural purposes);

• contaminating the soil; or • cutting any roots with a diameter of greater than 50 mm.

The authority for registration, approvals and the issuing of tree protection directions is the Conservator of Flora and Fauna, who is backed up by a Tree Advisory Panel.

Penalties for offences range from 50-400 “penalty units” (currently for an individual $5,500- $44,000 or for an offence committed by a corporation $27,500-$220,000).

SA significant tree clauses within the Development Act 1993 South Australia’s Development Act defines “damage1 to a regulated tree” as “development” for the purposes of the Act, in order for activities to be controlled.

It makes the distinction between two categories of trees located in the Adelaide metro area and the Adelaide Hills as “regulated” and “significant”. These are defined in the Regulations as:

• Regulated – trunk circumference of 2+ metres at one metre above ground level (for multiple trunks, the average circumference of each is 625+mm)

• Significant – trunk circumference of 3+ metres at one metre above ground (for multiple trunks, the average circumference of each is 625+mm)

Any activity which is “maintenance pruning”2 does not require approval, nor does pruning for powerlines or for trees planted for orchards or woodlots. Approval for any other removal or destruction requires advice to be provided through “an expert or technical report”, for which the minimum qualification is Cert V in Horticulture (arboriculture). If the “killing, destruction or removal” of a tree is approved:

• Two trees are required to be planted for a regulated tree; • Three trees are required to be planted for a significant tree, OR

1 “tree damaging activity” includes the killing or destruction of a tree, the removal of a tree, the severing of branches, limbs, stems or trunk of a tree, ringbarking, topping or lopping of a tree or any other substantial damage.

2 means that no more than 30% of the crown is removed, and the removal is done for the purposes of removing dead wood, diseased wood and potentially unsafe branches


• $75 per tree removed is to be paid into the local council’s Urban Tree Fund, which may be applied to either the planting of trees which will become significant, or the purchase of land for the planting of trees which will become significant

Penalties apply up to $60,000.

Exemptions

• Any tree which is located within 10 metres of an existing dwelling or existing in ground- swimming pool is fair game unless it is an Agonis flexuosa (Willow Myrtle) or any species of Eucalyptus.

• Any tree which is within 20 metres of a dwelling in a medium or high risk bushfire area is fair game (large slabs of the Adelaide Hills).

• Any declared pest plant is fair game, as are any on this “hit list”:

Acer negundo (Box Elder) Acer saccharinum (Silver Maple) Ailanthus altissima (Tree of heaven) Alnus acuminate subsp. Glabrata (Evergreen Alder) Celtis australis (European Nettle Tree) Celtis sinensis (Chinese Nettle Tree) Cinnamomum camphora (Camphor Laurel) Cupressus macrocarpa (Monterey Cypress) Ficus spp. (Figs), other than Ficus macrophylla (Moreton bay fig) located more than 15 metres from a dwelling Fraxinus angustifolia (Narrow-leaved Ash) Fraxinus angustifolia ssp. Oxycarpa (desert ash) Lagunaria patersonia (Norfolk Island Hibiscus) Melaleuca styphelioides (Prickly-leaved Paperback) Pinus Radiata (Radiata Pine / Monterey Pine) Platanus x acerifolia (London Plane) Populus alba (White poplar) Populus nigra var. italica (Lombardy Poplar) Robinia pseudoacacia (Black Locust) Salix babylonica (Weeping Willow) Salix chilensis ‘Fastigiata’ (Chilean Willow, Evergreen Willow, Pencil Willow) Salix fragilis (Crack Willow) Salix X rubens (White Crack Willow, Basket Willow) Salix X sepulcralis var. chrysocoma (Golden Weeping Willow) Schinus areira (Peppercorn Tree)

Individual local Council development plans may also declare individual trees and stands of trees to be significant. This relies on councils identifying and lodging DPAs with the Minister for Planning, and only the Cities of Adelaide, Burnside, Prospect and Unley have taken this option.

Victorian planning and local government laws delegate to local government Vegetation is most commonly managed under the State’s Victorian Planning Provisions (VPP), and at a local government level through Vegetation Protection Overlays (VPOs). 52 of the 82 local councils use Vegetation Protection Overlays (VPOs) to manage their tree populations whereby each individual council will specify local vegetation for protection in a schedule (which requires Ministerial approval). Vegetation in the schedule may include trees, stands of trees or areas of significant vegetation.


There is nothing in the VPP that defines a significant tree. Councils are individually responsible for determining this. The reason for this relates to the aesthetic and heritage value of the tree species native to the council area in question. Each council will set its girth threshold to determine ‘what is a significant tree?’ at a level which will allow for protection of trees that are desirable for the district.

Other overlays in Victoria include Environmental Significant Overlay, Significant Landscape Overlay, Heritage Overlays, Erosion Management Overlay and Salinity Management Overlay. The National Trust advocates for the use of Heritage Overlays in local government planning scheme to protect trees.

As an alternative to instruments within the VPP, councils may create a local law under the Local Government Act 1989 to protect vegetation. For instance, the City of Bayside Environmental Local Law No. 2 protects identified significant trees on its significant tree register or existing tree canopies on private properties for their amenity value.

Regardless of which instrument is used by councils, significant tree registers are usually created after conducting a council-wide survey and alerting the owner if the tree occurs on private land. Anyone may nominate trees or vegetation for inclusion. The register is then published, complete with reasons for each tree’s inclusion, with photographs and comments about how to best manage the tree for optimal health. The schedules include a definition of a significant tree. In all 52 councils girth size was used to help determine a tree’s significance, which vary from as narrow as 400mm to 3500mm.. All 52 councils however use a combination of methods such as:

• Canopy size • Prescribed lists (approximately 50% of councils had a significant tree list) • Heritage value • Aesthetic value

Permits are required prior to removal, destruction or lopping.

Penalties for breaches are through infringement notices and minor penalties, with larger fines for breaches of court orders. This regime has come under criticism because the largest fines only occur once it has come to the attention of authorities that damage or destruction has taken place and an order has been made, in other words, “after the horse has bolted” 3. Victoria could consider whether fines are adequate and whether the State government should play a role rather than leaving the action to councils to prosecute.

New South Wales planning provisions delegated to local government In Sydney and areas zoned "residential", "village", "township", "industrial" or "business", it is the responsibility of local councils to manage tree populations and there is not a uniform system in place as each council forms its own planning guidelines. Councils have two tools to manage trees in NSW – Tree Preservation Orders (TPOs) and Local Environment Plans (LEPs).

LEPs allow for the incorporation of significant tree registries but this is not compulsory. A majority of councils have significant tree registries.

The cities of Gosford, Randwick, Manly, Sydney and the Sutherland Shire all use the following policy guidelines to determine the significance of trees:

• Landscape amenity • Historical importance • Botanical importance

3 A recent case of a developer in Toorak resulted in a fine of $5,000 plus court costs of $8,000.


Gosford, Manly and the Sutherland Shire have the additional guidelines of: • Aboriginal importance • Functional purpose (shade, habitat, avenue windbreaks)

I am advised by the NSW Planning department that girth and canopy sizes are not used as guidelines to determine a significant tree.

In addition to LEPs councils and shires use TPOs to control the pruning and removal of trees that are not listed as significant. TPOs apply to native and non-native species. I surveyed 10 councils in the metropolitan area and 10 in the regions and all listed the height and canopy size of a tree as the guidelines of protection. Girth size was not used

An example:

Trees more than 3 metres high, or with a crown of more than 2 metres will require a permit to remove.

Most councils did not vary too much from this example. Gosford lowered its height limit to 2 metres but generally 3 metres is widely accepted.

Pruning of no more than 1/3 of the canopy (NOT the trunk) is uniformly allowed across the state.

The NSW Government has introduced a new Standard Instrument LEP “Preservation of trees or vegetation” (5.9) to encourage the standardisation of LEPs across local council areas and replace individual TPOs. The objective of the standard is “to preserve the amenity of the area, including biodiversity values, through the preservation of trees and other vegetation”. It applies to “species or kinds of trees or other vegetation that are prescribed for the purposes of this clause by a development control plan made by the Council”. Councils may prescribe the trees or other vegetation by reference to species, size, location or other manner.

The standard LEP makes it illegal to ringbark, cut down, top, lop, remove, injure or wilfully destroy any prescribed trees or other vegetation without permission (pest species are exempt).

The maximum penalty for breach of a TPO in a Local Court is $110,000. The maximum penalty in the Land and Environment Court is $1.1 million.

NOTE: The NSW legislation actually allows for either State or Local government to make orders regarding tree management yet it’s not compulsory for either to do so. There seems to be an agreement with respect to cost sharing that councils manage the state’s trees but there is no legal obligation for them to do so.

Western Australia – planning provisions also delegated to local government Obtaining comprehensive information about WA “laws” difficult because it is delegated to local government, and those schemes are neither easy to find nor consistent with one another. Their “laws” often include trees on public land as well as private trees (which would be at greater risk).

Registers of significant trees and “tree preservation orders” can be identified by local councils through their local planning schemes, which are enabled through Part 5 of the Planning and Development Act 2005 (although the Act does not specifically refer to significant trees).

Uniquely, all councils in WA appear to use significant tree registers. Criteria include size4 (height, canopy and girth) as well as heritage and indigenous/native value, however criteria do vary across Councils.

4 Of 20 councils surveyed by my office, none used set guidelines for size, preferring to judge each on a case-by- case basis.


Some Councils have elaborate criteria, such as the City of Mandurah: 1. Outstanding Visual/Aesthetic Significance

a) Tree/s that is outstanding for its/their height, trunk circumference or canopy spread; b) Tree/s that occur in a prominent location or context; c) Tree/s that contribute significantly to the landscape in which it/they grow (including

streetscapes, parks, gardens or natural landscapes); d) Tree/s that exhibit an unusual growth form or physical feature, including unusually

pruned forms; or e) Tree/s that are particularly old or vulnerable.

2. Botanic/Scientific Significance a) Tree/s that are of an important genetic value that could provide important and

valuable propagating stock. This could include specimens that are particularly resistant to disease or climatic extremes or have a particular growth form; or

b) Tree/s that demonstrate a likelihood of producing information that will help the wider understanding of natural or cultural history by virtue of its use as a research site, teaching site, type locality or benchmark site.

3. Significant Ecological Value a) Priority, rare, threatened or locally uncommon species or ecological community; b) Indigenous remnant tree/s that predate the urban development in its immediate

proximity; c) Tree/s that make a significant contribution to the integrity of an ecological

community, including its role as a seed source or specialised habitat; d) A remnant specimen now reduced in range or abundance, which indicates the

former extent of the species, particularly range limits; or e) Tree/s which is a significant habitat element for rare, threatened, priority or locally

uncommon or common native species. 4. Historical, Commemorative, Cultural or Social Significance

a) Tree/s that are associated with public significance or important historical event; b) Tree/s highly valued by the community or cultural group for reasons of strong

religious, spiritual, cultural or other social associations, including trees associated with aboriginal heritage and culture;

c) Tree/s associated with a heritage listed place and representative of that same historic era; or

d) Tree/s that have local significance, are important to the local community and/or are recognised features of the immediate landscape

The City of South Perth uses the National Trust’s criteria.

Pruning of more than 1/3 of the canopy is not permitted.

Penalties exist for any breach of a planning scheme (s. 218) of Planning and Development Act 2005: The “General penalty” is “a fine of $200 000 and, in the case of a continuing offence, a further fine of $25 000 for each day during which the offence continues” (s 223), or an infringement notice fee of $500 (s 42 of the Planning and Development Regulations 2009). The likelihood of the general penalty provision being used for an individual tree is probably minimal and there was little information about the issuing of infringements or any examples of prosecutions.

A petition to the WA Parliament’s Standing Committee on Environment and Public Affairs in 2007 resulted in a recommendation that a model tree policy be developed, however this has not occurred and the policies remain with local government authorities.


Tasmania – protection through planning provisions Tree protection in Tasmania is similar to NSW and WA, that is, it’s planning legislation (Land Use Planning and Approvals Act 1993) enables councils to establish Planning Schemes to control land use and vegetation. Of its 29 councils, the majority have significant tree registers, some of which have tree protection orders, for which a permit is required to remove or prune a tree. Councils generally advise residents to seek council permission prior to removing trees on their properties, unless it is close to a house, a fire risk, causing problems with drainage, or is diseased.

Councils have a wide variety of approaches to significant trees:

• Hobart City Council used National Trust criteria when it established the list, and has since put out several public calls for nominations

• Kingsborough Council has used Royal Tasmanian Botanical Gardens criteria, that is trees must fit at least one of the following criteria: tree size and/or age, aesthetic beauty, rarity, unusual physical form, historical significance or landscape significance.

• A council which doesn’t use a list, the Derwent Valley Council, in contrast to the above examples simply requires a permit to remove a tree more than 3 metres tall, regardless of species. If the tree poses a bushfire danger the tree can be removed.

Tasmania has fines of up to $10,000. Queensland – protection through Local Government Act 1993 “local laws” Tree management in Queensland is very complex as Councils have their own local laws with different criteria for recognition. A reform process to develop template “model local laws”, however none has been developed yet for trees and/or vegetation. Furthermore, regardless of whether trees are indigenous or not, they are often classed as “vegetation” (as distinct from native vegetation).

Queensland’s Department of Local Government provides an online database of local laws at: http://www.dsdip.qld.gov.au/local-government/local-laws-online.html, which shows the diversity of classifications and laws which apply. They include the following titles:

• Protection of vegetation • Natural Assets Local Law • Preservation of Trees • Vegetation Management

The Cherbourg and Domadgee Aboriginal Councils protect trees of a girth of 50 cm (at the base) or more from ring-barking, cutting down, topping, removing, poisoning, injuring or wilful destruction. Pruning of trees “for the purpose of regeneration or ornamental shaping” is permitted. Damage to trees is allowed:

• with written Council permission; • if the Council has certified in writing that the tree is dying, dead, diseased or

potentially dangerous; • where the tree or trees are with the path of proposed roadways, sewerage works,

drainage works etc; or • where the tree or trees are within a building site, within 3 metres of any existing or

proposed building.


http://www.dsdip.qld.gov.au/local-government/local-laws-online.html


Barcoo Shire Council (among others) uses Vegetation Protection Orders for “significant vegetation”, which is defined as:

a) a valuable part of the natural heritage of the area; or b) an example of a rare or threatened species or a species that may be, or may be about

to become, a rare or threatened species; or c) a valuable scientific resource; or d) valuable source of propagating stock or of other horticultural value; or e) of historic significance because of its association with an important historical event

or the commemoration of an important historical event; or f) of cultural significance because of its significance in Aboriginal rituals, religious

observance or legend; g) a valuable educational or recreational resource; or h) a significant habitat for native animals (including native or migratory birds) or a part

of a fauna and flora corridor; or i) a significant part of a vegetation system or other ecological system; or j) important for maintaining the life-supporting capacities of ecological systems for

present and future generations; or k) important for protecting a water catchment area; or l) important for its support for natural or artificial landforms such as drainage lines,

watercourses, bodies of water, foreshores, slopes or unstable and erodible soils; or m) important for its aesthetic value or its beneficial effect on the amenity of the locality

in which it is situated; or n) important for its age, height, trunk circumference, or canopy spread; or o) important for its unique contribution to the landscape; or p) a visual buffer against unsightly objects or a buffer against pollutants, light spillage,

noise or other factors that have an adverse effect on the environment; or q) important as a buffer zone adjacent to areas of conservation significance; or r) important in the context of the objectives of State or Local Government planning,

land management, and environmental management policies and initiatives; or s) significant for such other reason as may be prescribed by local law policy.

Example - A local law policy might, for example, state that the protection of vegetation is of paramount importance if the land on which the vegetation is situated is -

· a ridge top; · an escarpment; · a steep slope; · land within a specified distance of a natural drainage line, a watercourse, a body of water or a foreshore; · land liable to damage from salinity; · land with unstable soil or soil that is liable to erosion

VPOs can only apply on private property and cannot apply to vegetation grown for commercial purposes. The process is that anyone may make a submission, notice must be given to the owner and the vegetation must be described by the Council. Council must receive expert advice and a management plan is then made and registered. Damage to the vegetation is permitted on receipt of a permit from Council. Penalty – 850 penalty units, currently $93,500.

Brisbane City Council’s Natural Assets Local Law 2003 provides that a "significant landscape tree" means a tree—


a) described in schedule 2 and growing within the Emerging Community Area shown on the Planning Scheme Maps in Brisbane City Plan 2000 as amended from time to time; or

b) included in a register in a Planning Scheme Policy under Brisbane City Plan 2000 as amended from time to time; or

c) protected under a vegetation protection order in the class IT2.

Significant Landscape Trees in Brisbane City Council

SPECIES COMMON NAME DIMENSIONS

Ficus- benjamina, obliqua, platypoda, microcarpa var. hilii, bengaliensis, macrophylla, religiosa, virens, watkinsiana

Fig trees Greater than or equal to – 100 cm trunk diameter*

Mangifera indica Mango trees Greater than or equal to – 80 cm trunk diameter

Delonix regia Jacaranda mimosifolia

Poinciana Jacaranda

Greater than or equal to – 80 cm trunk diameter

Araucaria - cunninghamia, bidwillii Agathis robusta

Native pines Greater than or equal to – 60 cm trunk diameter

Eucalyptus tereticornis Eucalyptus microcorys Eucalyptus racemosa

Forest Red Gum Tallow wood Scribbly gum

Greater than or equal to – 60 cm trunk diameter

*In all cases, trunk diameter is measured at a point 1.0 metre above the “natural” ground level – that is, the ground level prior to the commencement of any works

It also allows for VPOs with similar provisions to Barcoo Council.

It is allowable to “interfere” with protected vegetation without a permit under this local law if that interference constitutes—

a) interference with protected vegetation as permitted under an existing authorisation mentioned in section 48 of this local law;

b) removal of trees or parts of trees that are causing an immediate and significant threat to persons or property as demonstrated by— (i) adequate photographic evidence submitted to Council within 10 business days of the occurrence of the threat event; and, if requested (ii) an arborist's report;

Examples of emergency situations— • Split tree trunks;


• Leaning tree(s) with soil upheaval.

c) removal of vegetation— (i) where the removal is essential for emergency access or emergency works; or (ii) where the removal is immediately required in response to an accident or emergency;

d) pruning to accommodate overhead and underground utilities in accordance with standards agreed between Council and the utility provider;

e) pruning vegetation other than a significant landscape tree for the purpose of maintenance or hazard management, as long as— (i) no more than 20% of the live foliage volume of a tree or shrub is removed in any 12-month period; and (ii) the part removed is distributed sufficiently evenly over the whole crown that the tree or shrub is not left lop-sided.

Example for (ii)— Pruning of overhanging foliage of a tree whose trunk is on adjoining land will not be exempt if the overhanging foliage represents 20% of the live foliage volume or, if less than 20%, removal of all the overhanging foliage leaves the tree lop-sided.

f) removal of a tree or part thereof, other than a significant landscape tree, as long as— (i) the whole trunk is located within 3 metres of an existing lawfully constructed building on a property less than or equal to 4000 square metres in area; or (ii) the whole trunk is located within 6 metres of an existing lawfully constructed building on a property greater than 4000 square metres in area;

g) interference with pasture vegetation; h) interference with garden vegetation other than—

(i) a significant landscape tree; or (ii) a tree greater than 30 cm in trunk diameter;

i) constructing a boundary fence, as long as the vegetation that is interfered with— (i) is located within 3 metres of a property boundary; and (ii) is smaller than 20 cm in trunk diameter; and (iii) not a significant landscape tree; and (iv) is not in a waterway corridor or wetland.

j) the removal of a dead tree where that tree is— (i) smaller than 20 cm in trunk diameter, and (ii) is not providing habitat for native fauna;

k) the removal of a dead limb where that limb is— (i) smaller than 20 cm in diameter, and (ii) is not providing habitat for native fauna.

In its reparation, it provides a number of examples (which makes it difficult to know what conditions it will actually apply!):

Council may impose conditions relating to the following examples— Requiring —

• removal of vegetation to be effected in such a manner as to ensure that adjacent protected vegetation is not damaged;

• a copy of the permit to be made available to all persons involved in vegetation clearance, earthworks and other works on the site before vegetation clearing commences;

• three replacement trees to be planted for each tree removed pursuant to the permit; • a replacement tree, of a particular species or dimensions, or both, to be provided in a

specified location;


• all surface areas of batter slopes associated with site works to be suitably mulched to an average depth of 100 mm, in addition to replanting or other treatment, in order to reduce the potential for batter destabilisation and soil erosion;

• an erosion and sediment control plan to be submitted which— identifies how the applicant intends to control potential erosion and sedimentation due to

site works; is consistent with Council’s current erosion and sediment control standard; and is satisfactory to Council; provides for trees to be retained to be protected by fencing around the root

zone that is constructed— prior to the commencement of, and retained until the completion of, works; and of materials adequate to protect the vegetation from site works and machinery.

• that no material is to be stockpiled, vehicular machinery used, or excavation occur— within 5 metres of the base of the trunk; or within the root zone;

of any tree(s)to be protected; • the root zone to be fenced off; • the officer named at the top of the permit to be notified of the proposed

commencement date of vegetation clearance pursuant to the permit, not less than two working days prior to the commencement of clearance;

• adjoining owners to be notified not less than two working days prior to the commencement of clearance of the type and proposed commencement date of vegetation clearance pursuant to the permit;

• excluding root systems and basal stumps from the vegetation authorised to be removed pursuant to the permit5;

• the permit holder to effect the interference in a specified manner which may include implementing an approved management plan;

• declaration of compliance to be completed and returned by due date.

Pruning conditions may specify which branches of a tree may be removed.

Contravention of the local law may result in issuing of a compliance notice, with a penalty of up to $55,000. If Council needs to undertake reparation works, it can recover costs.

Gold Coast City Council’s local law defines "protected vegetation" as that which is:

a) equal to or in excess of 40 centimetres in girth DBA (Diameter Breast Height)(measured at 1.3 metres above average ground level); or

b) equal to or in excess of 4 metres in height (in areas zoned Rural, Park Residential or Future Urban under the Planning Scheme as at the date of making of this Local Law); or

c) subject of a vegetation protection order that is in force under this local law.

Furthermore, the Urban Land Development Authority Act 2007applies to areas under the Urban Land Development Authority. Within its definition of “controlled vegetation”, “significant landscape trees” are:

• Ficus-benjamina, obliqua, platypoda, microcrapa var.hillii, bengaliensis, macrophylla, religiosa, virens, watkinsiana (Fig Trees) with a trunk diameter 100 cm or larger

• Mangifera indica (Mango) with a trunk diameter 80cm or larger • Delonix regia (Poinciana) with a trunk diameter 80cm or larger

5 Retention of root systems and basal stumps is important in maintaining bank stability


• Jacaranda mimosifolia (Jacaranda) with a trunk diameter 80cm or larger • Araucaria cunninghamii (Hoop Pine) with a trunk diameter 60cm or larger • Araucaria bidwillii (Bunya Pine) with a trunk diameter 60cm or larger • Agathis robusta (Queensland Kauri Pine) with a trunk diameter 60cm or larger • Eucalyptus tereticornis (Forest Red Gum) 60cm trunk diameter or larger • Eucalyptus microcorys (Tallow Wood) 60cm trunk diameter or larger • Eucalyptus racemosa (Scribbly Gum) 60cm trunk diameter or larger.

Measurements are conducted at a point 1 metre above the natural ground level.

Queensland has a Neighbourhood Dispute Resolution Act 2011 which includes shrubs, vines, cacti, palms, dead trees and stumps in its definition of trees. It places the responsibility for maintenance with the owner and enables neighbours to take action on overhanging branches.

Northern Territory Neither the Northern Territory parliament nor any councils offer protection to trees which are on private land (except for any which may be listed as part of a heritage item under the Heritage Conservation Act). Councils do have bylaws protecting trees on public land. The National Trust has attempted to bring the plight of significant trees on private land to the community’s attention.

Reviews of legislation in the last five years New South Wales reviewed its Trees (Disputes Between Neighbours) Amendment Act in 2009, amending Bill passed in 2010 South Australia – provisions within the Development Act reviewed in 2007, came into effect in 2011 Queensland - introduced the Neighbourhood Dispute Resolution Act 2011 and is also reviewing the Vegetation Management Act 1999

Discussion What is best practice?

Which laws best protect biodiversity in urban landscapes?

Should trees be managed on a regional basis through species lists?

Would neighbourhood laws similar to Qld and NSW alleviate most of the community angst about large trees?

Local government has a critical role. In many jurisdictions it promulgates its own local laws and planning instruments. Even when a State statute exists (SA) it is still the level of government which administers that legislation. The interest and resources of individual councils in developing registers can lead to an ad hoc approach.

There is a lack of consistency with so many different approaches – does this matter?

Should each State and Territory have a “safety net” to protect trees, such as we have in SA, whereby the rules are much the same (at least across the metro area)? In fact, due to risk aversion at local government level, the laws in SA took much of the decision making away from local government (as Dr Bob Such regularly reminds us).

SA’s laws are more detailed than other states, especially since the Act was amended and new Regs promulgated; if laws are more detailed there is an obligation to get those details right! If that were the case, we would have a right to call them “sophisticated” or “well developed”.


Laws may have developed differently in different states reflecting the historical clearance of native vegetation eg SA metro has v little in metro area c/f other jurisdictions which have scattered remnants?

Importance of the National Trust in supplementing tree protection laws Supplementary role of the National Trust in preserving trees which might not meet statutory or local government criteria – Vic criteria used as a guide in Department of Planning and Community Development’s “Practice Notes” and frequently referred to be Victorian local councils, Tas (see Adam’s notes), NT.

National Trust criteria in Victoria

1. Horticultural and/or genetic value 2. Unique location or context 3. Rare of localized distribution 4. Particularly old specimen 5. Outstanding size (girth, head and canopy) 6. Aesthetic value 7. Curious growth habit 8. Historical significance 9. Connection to Aboriginal culture 10. Outstanding example of species

National Trust of SA

1. Historical 2. Cultural 3. Aesthetic (“magnificent) 4. Intergenerational (replacement for dwindling stock of significant trees) 5. Rare – unexpected as a species, or in unusual location 6. Remnant vegetation 7. Scientific (used in pharmacology) 8. Location and context (elements for historical and cultural reference) 9. Monetary value


State by state (or territory) ACT Nature Conservation Act

1980

Tree Protection Act 2005 Heritage Act 2004

Local government registers?

• National parks, declaration of species (either for protection or as pests), native vegetation, protection of native timber

• Australia’s only tree-specific law • Excludes trees in “built up urban areas”, referring

them to the Tree Protection Act

n/a – ACT Legislative Assembly is also the local council NSW National Parks and Wildlife

Act 1974 Threatened Species Conservation Act 1995 Native Vegetation Act 2003 Environmental Planning and Assessment Act 1979 Heritage Act 1977 Trees (Disputes Between Neighbours) Amendment Act


• Parks, declarations, Aboriginal lands, marine mammals, ecological communities

• Declaration of species, also looks at recovery and “bio- banking”

• Native vegetation, including trees, understorey plants, groundcover and plants in wetlands

• Empowers local government to implement tree protection through Environmental Planning Instruments (EPIs) – cl 26(1)(e)

• Only protects trees if they form part of heritage item • Aims to resolve neighbour disputes re trees

Yes NT Territory Parks and

Wildlife Act Planning Act

Heritage Conservation Act


• National parks, declaration of species (either for protection or as pests)

• Must take into consideration in approving planning approvals “any potential impact on natural, social, cultural or heritage values”, but no reference to trees

• only if identified as a heritage object or a heritage place (s 26), no specific tree reference in the Act; the register has ?12 trees on it

None. The National Trust and Greening Australia have a significant tree register of potentially 120 trees, but they have no legal protection

QLD Nature Conservation Act 1992 Vegetation Management Act 1999

Sustainable Planning Act 2009 Urban Land Development Authority Act 2007 Aboriginal Cultural Heritage Act 2003

Torres Strait Islander Cultural Heritage Act

• National parks, Aboriginal lands, forests, declaration of species (either for protection or as pests)

• Native vegetation that is remnant to protect ecosystems + veg in areas declared as high conservation value; excludes grasses and mangroves

• Sets out how planning can occur in Qld while promoting “ecological sustainability”

• Controls the clearing of certain vegetation within a specific development; bylaws – much more detail

• Aboriginal heritage protection, no specific reference to trees

• Ditto


Queensland Heritage Act 1992 Neighbourhood Dispute Resolution Act 2011


• Only protects trees if they form part of heritage item

• Aims to resolve neighbour disputes re trees and

fences

Not registers, but many have bylaws: Barcoo, Boulia, Bulloo, Brisbane, Cairns, Cherbourg Aboriginal Shire, Doomadgee Aboriginal Shire, Gold Coast, Ipswich, Lockhart River, Palm Island Aboriginal Shire, Quilpie, Redland, Sunshine Coast, Whitsunday, Winton

SA Native Vegetation Act 1991 Development Act 1993 Heritage Places Act 1993 ?Aboriginal Heritage Act


• Native vegetation; applies to non-metro parts of the State + the Adelaide Hills

• Quite detailed • Only protects trees if they form part of heritage item,

Act does refer to trees

Only the Cities of Adelaide, Burnside, Prospect and Unley, under the Development Act 1993

TAS Nature Conservation Act 2002 Land Use Planning and Approvals Act 1993

Historic Cultural Heritage Act 1995 Aboriginal Relics Act


• National parks, conservation covenants (private land), protected species, Aboriginal lands

• empowers councils but only reference to trees is that pruning falls within the category of “works”; councils can adopt Planning Schemes to control and protect land use and vegetation

• Only protects trees if they form part of heritage item; no specific reference to trees


Hobart, Kingsborough, Dorset, Georgetown – Tree protection orders + registers

VIC Flora and Fauna Guarantee Act 1988 Conservation, Forests and Land Act 1987 Planning and Environmental Act 1987

Heritage Act 1995

Aboriginal Heritage Act


• Declarations of protected species

• Aboriginal lands, forests, reserve system, crown leases etc

• State and local planning schemes; local councils may include a “planning overlay” /sig tree register (scheme must be approved by the Minister) ; no explicit ref to “tree” in the Act;

• In definitions, specifically includes “tree” as a heritage

place • Aboriginal heritage protection, no specific reference

to trees

Yes, under Local Government Act 1989 WA Wildlife Conservation Act

1950 Conservation and Land Management Act 1984

• Protected flora and fauna

• Land and marine reserves, forests


Environmental Protection Act 1986 Planning and Development Act 2005 Heritage of Western Australia Act 1990 Aboriginal Heritage Act 1972


• EPA, native vegetation, declared areas, waste, pollution

• Local planning schemes are enabled through Part 5

• Only protects trees if they form part of heritage place


Yes, most/all councils have through local planning schemes in Planning Act

Acknowledgements SA Parliamentary Library

References/resources All Acts and Regulations: Australasian Legal Information Institute: http://www.austlii.edu.au/

ACT ACT Territory and Municipal Services “ACT Tree Register”: http://www.tams.act.gov.au/live/environment/treeprotection/acttreeregister

NSW NSW EDO Factsheet “Trees and Native Vegetation”, accessed at http://www.edo.org.au/edonsw/site/factsh/fs05_3.php Department of Planning and Infrastructure Land and Environment Court Tree Dispute Information, accessed at: http://www.lawlink.nsw.gov.au/lawlink/lec/ll_lec.nsf/pages/LEC_tree_disputes_information

NT National Trust Register of Significant Trees, accessed at: http://www.nationaltrustnt.org.au/files/Significant- Tree-Register.pdf

QLD Queensland Civil and Administrative Tribunal “Trees and the Law” accessed at: http://www.qcat.qld.gov.au/using-qcat/faqs/faq-tree-disputes Department of State Development, Infrastructure and Planning, local law search facility Department of Local Government local laws database at : http://www.dsdip.qld.gov.au/local- government/local-laws-online.html Department of Justice and Attorney-General “Tree Disputes Q&A” accessed at: http://www.justice.qld.gov.au/corporate/justice-initiatives/neighbourhood-disputes-resolution-act-2011/trees

SA Regulated Trees amendment, accessed at: http://www.sa.gov.au/subject/Housing,+property+and+land/Building+and+development/Building+and+develo pment+applications/Development+plans+and+their+use/Amendments+to+development+plans+proposed+by+ the+minister/Regulated+trees+amendment

TAS

VIC


http://www.austlii.edu.au/

http://www.tams.act.gov.au/live/environment/treeprotection/acttreeregister

http://www.edo.org.au/edonsw/site/factsh/fs05_3.php

http://www.lawlink.nsw.gov.au/lawlink/lec/ll_lec.nsf/pages/LEC_tree_disputes_information

http://www.nationaltrustnt.org.au/files/Significant-Tree-Register.pdf



http://www.qcat.qld.gov.au/using-qcat/faqs/faq-tree-disputes




http://www.justice.qld.gov.au/corporate/justice-initiatives/neighbourhood-disputes-resolution-act-2011/trees

http://www.sa.gov.au/subject/Housing%2C%2Bproperty%2Band%2Bland/Building%2Band%2Bdevelopment/Building%2Band%2Bdevelopment%2Bapplications/Development%2Bplans%2Band%2Btheir%2Buse/Amendments%2Bto%2Bdevelopment%2Bplans%2Bproposed%2Bby%2Bthe%2Bminister/Regulated%2Btrees%2Bamendment



Department of Planning and Community Development (DPCD) VPP Practice Note “Vegetation Protection in Urban Areas”, 1999 accessed at http://www.dpcd.vic.gov.au/ data/assets/pdf_file/0010/41698/Veg_Protection_complete_note.pdf DPCD VPP 52.17 accessed at: http://planningschemes.dpcd.vic.gov.au/aavpp/52_17.pdf National Trust of Australia (Victoria): Protection of Significant Trees

WA Legal Aid “Dividing Fences and other boundary issues” accessed at; http://www.legalaid.wa.gov.au/InformationAboutTheLaw/Homes/neighbours/Pages/Dividingfences.aspx


http://www.dpcd.vic.gov.au/__data/assets/pdf_file/0010/41698/Veg_Protection_complete_note.pdf

http://www.dpcd.vic.gov.au/__data/assets/pdf_file/0010/41698/Veg_Protection_complete_note.pdf

http://planningschemes.dpcd.vic.gov.au/aavpp/52_17.pdf

http://www.legalaid.wa.gov.au/InformationAboutTheLaw/Homes/neighbours/Pages/Dividingfences.aspx

Cultural Significant Trees – A Management Tool for Local Government

S. Cassar, C. Lawry, D. Cooney, G. Williams, D. Lawry

Introduction Many Council’s are now proactively managing their trees as assets, and are identifying those with special relevance to the community.

Councils including Mount Barker have adopted the Tree Protection Policy under the Development Act 1993, but this only covers limited attributes of trees which are defined under the Act. Some trees in rural areas are protected under the Native Vegetation Act 1991, but once again many trees fall through the gaps with these processes.

Indigenous communities have many culturally modified trees, such as canoe and shield trees, are recognised under the Aboriginal Heritage Act.

Trees may be important for a number of reasons, such as formal plantings as memorials (RSL Avenues of Honour) or less formal plantings in recognition of a person or event (such as trees reflecting a visit by a dignitary, or in remembrance of a person who has died).

Some are excellent examples of specific trees, either as individual specimens or as part of a continuous avenue planting and representative of a specific period of urban design.

Many of these plantings are now in decline or under threat. (As an example of this, many first world war plantings were of the “Lone Pine”, - Pinus halepensis. These plantings are now over 90 years old, and have a safe lifespan of 80-100 years. Many of these senescent trees are becoming hazardous. Some have been damaged or lost due to road works or other infrastructure maintenance or development, and incomplete avenues may lose a great deal of their significance in the landscape. In some cases the reasons why some of these individual or avenues were planted can no longer be remembered.

Many individuals and organisations are becoming increasingly concerned about the decline in memorial and culturally important tree stocks. Organisations such as the RSL, the Department of Veterans Affairs, the National Trust, the Heritage Branch of the Department of Water, the Environment and Natural Resources and TREENET are providing Councils with information about the location of these surviving or lost trees. While this is helpful it has highlighted our lack of information about the significance of many trees in our care.

Discussion The District Council of Mount Barker received funding support through the LGA Research and Development fund to develop guidelines and a criteria and checklist which can be used to assess trees against to identify those with special significance for the local or broader community.

Council staff established a working party, with representation from other Councils and key stakeholder groups to develop a project brief which clearly defined the scope and aims of the project.

Project Brief

• Identify key stakeholders at local, regional, State and Federal levels. • Develop a standard consultation process for use with all key stakeholders (and agreed by the

National Trust). • Create a methodology to generate a register of all culturally important trees. • Develop a set of criteria to measure trees against to rate their significance. • Develop an audit checklist to provide information on the status, health, completeness (of avenues)

risks (current and potential) and site constraints for these trees. • Develop templates for setting management strategies against timelines.


• Develop a checklist to ensure the concurrence of all specific stakeholders and with all relevant legislation.

Implementation David Cooney , DC of Mt Barker was responsible for the successful procurement of funding from the LGA and in kind support from others. He managed all reporting to stakeholders and disbursement of LGA grant funding.

David Lawry, Director of TREENET, was commissioned to coordinate the project and facilitate the distribution of the final document and for it to be presented and promoted through the Treenet forum. Sam Cassar of Symatree Pty Ltd was engaged to undertake all research and to write the final document.

Fundamental to the broad acceptance of the Guidelines was the development of a process to assist with the identification and engagement of key stakeholders (such as the RSL and the National Trust) when considering the management , replacement or relocation of culturally significant trees. The guidelines have been completed and are available for other Councils to use via the TREENET and LGA websites. It is hoped that the guidelines will be promoted nationally for use by Councils through the LGA, TREENET , The National Trust and the RSL among many other stakeholder groups.

Conclusion This project developed principles and guidelines to assist Council’s to recognise, identify and manage culturally important trees. Application of the methodology should allow Council’s to objectively plan for short and longer term succession plantings to ensure the continued representation of these trees in the built and natural environment. It will allow organisations and individuals to liaise with bodies such as the RSL and the National Trust on issues relating to culturally significant trees, and assist communities in the preservation and management of the values these trees represent.


Sustaining Urban Forest – Lessons from Laman Street, Newcastle

Philip Hewett

City of Newcastle NSW Background In the early 1930’s the industrial city of Newcastle NSW, encouraged by Mayor Ald C J Parker, began extensive planting of trees, especially Hills Weeping Fig, to ameliorate the environmental and visual impacts of its mining and steel making industries. Some of the inner city streets were planted with Hills Fig in the unsealed road shoulder or in the footpath. The surviving mature fig trees now extend many metres over and above roofs because most buildings have shallow or non-existent street setbacks.

David Bidwell, Senior Horticulturist, Arboriculture, at the Sydney Royal Botanic Gardens thinks the earliest planting of Hills Fig in NSW is the stand lining Art Gallery Road in the Sydney Domain. These trees were planted in 1915. Unfortunately at least three of the trees are infected by the root pathogen Phellinus noxius. (pers comm) By the early 1930’s these Sydney Domain Figs would have given little indication of their mature form so Newcastle’s pioneering tree planters had little, if any reliable information about the ultimate size, both above and belowground, of the Figs they were planting in city streets during the 1930’s.

Over the last two decades many of the original Hills figs grown in Newcastle streets have been removed due either to failures, or to unmanageable conflicts with property, utilities, roads and infrastructure. Many of the surviving trees form tall, dense, interlocking canopies in streets and footpaths of the inner city. In common with most fig species, Hills Fig develops root buttresses producing a pronounced zone of uplift of 2 to 3 metres width. When growing in a street environment this uplift inevitably displaces kerbs and pavement, blocks fractures pipes, and become interlocked with buried utilities.

Seventy years of urban development have taken toll on the surviving Hills figs as new utilities and drainage systems have been installed and older systems repaired, roads and footpaths reconstructed and sealed and the ubiquitous concrete driveways installed. The central carriageway of most streets is too compact to support root growth but the parking lane i.e. road shoulder is slightly less hostile, allowing roots to develop parallel with the kerb (linear) and to rise above the road surface to be continuously abraded and wounded by vehicles (photo above).

Throughout their first forty years the Newcastle Hills figs were routinely lopped to create a round-headed form of a ‘manageable’ size. The lopping created a low vase-like branch structure and when lopping was abandoned in the 1970’s the trees grew rapidly to form a tall multi-stemmed character.

Of all the issues relating to mature Hills figs in Newcastle streets, it is the linear (parallel to kerb) form of the root plate that presents the greatest challenge in managing risk. The close spacing (often less than 10m) between individual trees has created asymmetric and interlocking crown architecture. Linear root plates and


crown asymmetry are characteristics that contributed to the failure of Hills Fig trees in Tyrrell, Bruce, and Laman streets, Cooks Hill

Above - Comparing Hills Fig root crown in street (left) and park environs (right). Root linearity results when the natural habit of roots is constrained and deflected by infrastructure.

In February 2012, after nearly three years of intensive investigation, reporting and debate extending across two elected Councils, three General Managers and two Acting General Managers, the remaining fourteen trees in the Laman Street cultural precinct were removed in accordance with the Council resolution.

What did the City of Newcastle learn from the Laman Street experience and what, if anything, could other tree management authorities glean from the Newcastle experience?

This paper is focused mainly on the engagement processes rather than on the technical issues relating to the Laman Street trees. The General Manager, Phil Pearce succinctly clarified Council's position on the technical and risk issues in his January 2012 Media Release (Appendix 1): "Council has undertaken substantial investigation and analysis using both internal and external experts in arboriculture, engineering and other relevant professions. These experts have based their opinions on detailed knowledge of the site, evidence-based investigations and readily available relevant literature. Council is very comfortable with the conclusions drawn from those reports and the decision by the majority of the democratically elected Council to remove and replace the trees"

The Laman Street Engagement Processes – what was learnt? In October 2011 Council directed the General Manger to conduct a review of the Laman Street fig tree issue and report on an evaluation of the processes adopted by Council, with recommendations for improving Councils engagement processes in respect of issues of major community significance.

The report (1) Review of Laman Street Engagement Processes (the Review) was presented to Council in February 2012. Insights from the review of the Laman Street engagement processes may be of value to Councils and other authorities responsible for sustaining the benefits of urban forests despite a preponderance of mature aged trees approaching time for renewal.

The Review Council has been investigating tree failures throughout the Local Government Area since 2000 resulting in the collation of data known as the ‘case book history’ and adoption of a more strategic approach to assessing and managing trees.


The Review, prepared by staff selected because they had little or no direct involvement in the Laman Street processes, included a chronology of tree specific events from 2000 to 2011 and the associated Laman Street communication strategies and Council decisions - 243 separate items are listed. The sheer volume of information on the topic prepared by Council officers made it impossible to review all the information. However a significant amount of information was reviewed to inform the report and recommendations including:

• Media releases and clippings • Factsheet prepared for ABC television Stateline story • Transcripts from Public Voice meetings • Results of the Civic Cultural Precinct Laman Street Design workshop • Newcastle Voice 2010 and 2011 consultation reports • A Case History Informing Tree Management in Laman Street • Minutes of Council Project Control Group meetings • Presentation for the Councillor workshop held on 27 July 2010 • Council resolutions pertaining to the Laman Street fig trees • Minutes of the Laman Street Fig Trees Working Party • Minutes of the Urban Planning and design Advisory Committee

The Review analysed the following four aspects of the engagement process:

1. Community consultation methodologies and processes used by Council 2. Scope of information supplied to councillors and the community 3. Methods of communication between Council administration, Councillors, key stakeholders,

community groups and the media 4. Function and operation of the Laman Street Fig Trees Working Part, relevant strategic advisory

committees and Council.

The following are the principle points of interest to other organisations from each of these four aspects. I have added underlining in order to emphasise points.

Community consultation survey results With the benefit of hindsight, the decision to transfer the decision-making for what was an operational issue

managing tree risk) was not appropriate as it implied that alternatives could be considered when the evidence showed only one option was appropriate. This resulted in unnecessary and at times inaccurate debate in the Council chamber, public forums and the media.

Combining the Laman Street fig tree replacement strategy with the consultation process for the broader Civic Cultural Precinct design process was intended to provide opportunity for the community to have direct input into the new design. However some community members perceived that the future of the figs was still to be determined when in fact the decision had been made.

A recommendation to hold a community information session ahead of the design workshop was rejected because of concerns about increasing antagonism in the community and fears that those opposed to the decision would seize control of the session for their own purposes.

Not holding the information session may have impac ted on the c ommunity’ s ability to participate in the workshop in a meaningful way, as they may have not fully understood the complex issues, the decision-making processes, or their role in the process.

Social media as a communication tool. It was found that contrary arguments clouded the discussion as they were disseminated through formal and social media at the same time as the design workshop presentations. Council’s communication strategy did not make use of social media.

Workshop timing. Feedback received on the timing of the two-day design workshop was that it should not have been held on weekdays.


Scope of information supplied to Councillors and the community Management of the Laman street issues extended across two elected Councils, three General Managers and two Acting General Managers and in that time Council officers provided Councillors with a large volume of information consistently reinforcing that the trees pose a significant risk to public safety including:

• Root plate architecture • Wind loading • Quantified risk assessment • Social impact assessment • Heritage assessment • Fauna habitat assessment • Trenching investigation • Feasibility study for tree restraint system • Feasibility study into pull testing • Peer reviews of previous independent reports

Since April 2010 all independent reports addressing Laman Street trees were made available on Council’s website to mitigate criticisms about Council’s motives and decisions. A range of other materials were also posted to the website to enable the community to gain a full understanding of tree management in general and Laman street trees in particular.

The community campaign took advantage of:

• social media, • Public Voice presentations (by way of formal presentation to the full Council in chamber) • letters to the editor • petitions • individual representations to Councillors and the General Manager • reports from other authors supporting the contrary position

A key finding was that respondents to the various surveys indicated that they expected a ‘ju st d o it app roach ’ from Council, where significant issues are decided on and actioned swiftly without the use of excessive funds or resources. Respondents also commented on the need for the information to be completely transparent, where they are provided with simple, h onest, easy to understand ’facts’ from the onset.

The overwhelming number of requests from Councillors, community groups, the media, and members of the public impacted significantly on Council Officers ability to complete their regular duties. On average the Media Officer receives 70-100 requests a month regarding Council activities. In November 2011 over 200 requests were received on Laman Street alone.

The problem was exacerbated because there was no officer designated to manage the flow of information in and out of the organisation. This resulted in multiple areas working at times simultaneously on similar requests.

An Issues Management Plan was developed by the Communications unit to deliver a comprehensive information campaign to educate the community about the issues but the plan was not implemented due to other organisational priorities at the time.

From early 2010 there was an active campaign opposing Council’s position and criticising Council’s information and officers. This, combined with the media’s sustained coverage of the opposition’s position resulted in the Council’s key message of public safety being lost or diluted. A strategy of media releases to counter the claims was discussed but was not adopted.

When Council made efforts to correct misinformation, the information provided to journalists was rarely published.


A more proactive approach was adopted in late 2011 involving media interviews with the General Manager, including ABC’s Statewide program, publication of ‘Fig Forum light on facts’ (Appendix 2) on Council’s website, and a full page community announcement in the Newcastle Herald.

Methods of communication between Council administration, Councillors, key stakeholders, community groups and the media Council activities in relation to the Laman street trees were aligned with the IAPC2 Public Participation Spectrum. Information was provided in a variety of formats as in the following table. Category Communication Methods

Councillors Advice and meetings with the General Manager Council briefings Council workshops In Touch (Councillor newsletter) Media releases Mediation and meetings with members of Save our Figs Memos Notices on Councillor intranet Public Voice Quarterly Ward Forums Updates in Community Issues Reports Council Reports (including two Newcastle Voice consultation reports) Reports from Laman Street Trees Working Party Reports from Urban Planning and Design Strategic Advisory Committee

Key Stakeholders RSL, churches, art gallery, library, police

Signage in Civic Park, Laman Street and at the Art Gallery and Library Direct contact to inform of removal process and timeline

Community Groups and the Broader Community

Advertising in the Newcastle Herald Advertising in free newspapers (Star and Post) Council’s e-newsletter Council News (delivered to households in Newcastle Local Government Area) Newcastle Voice Newsletter (distributed to registered Newcastle Voice participants) Signage in Civic Park, Laman Street and at the Art Gallery and Library Quarterly Ward Forums Council’s website Responses to individual enquiries

Media Media releases Media conferences Media statements where required Responses to media enquiries

What were the most useful communication tools? The Councillor survey indicated that the most useful communications tools were briefings, advice and meetings with the General Manager, and memos.

The community survey indicated Local Newspapers and word of mouth as most useful.

Whilst Council employed traditional communications methods, community groups implemented an active campaign using alternative methods including social media and letters to the editor of the Newcastle Herald.

It is understood that the Newcastle Herald does not fact check letters before publishing them and this resulted in erroneous information being presented to the public. Council responded to some of the letters but the


publication cycle of the newspaper meant that Council’s response could not be published until the following day so there was a delay of at least 24 hours before correction.

Function and operation of the Laman Street Fig Trees Working Party, relevant strategic advisory committees and Council Council’s Strategic Advisory Committee structure allows for working parties to be formed reporting to the ‘parent’ committee which then reports to the Council as a whole.

Following a Council resolution on 14 December 2010, the Urban Planning and Design Advisory Committee (UPDAC) adopted a framework on 10 February 2011 for the composition of the Laman Street Tree Working Party (LSTWP).

There was a contradiction within the original Council resolution and within the Terms of Reference for the Working Party that compromised the success of the LSTWP from the outset. Both include the retention of the existing trees and implementation of alternative risk mitigation strategies. However, the basis of all the independent assessments had been the risks posed by the trees, and the issue for Council and its insurer were that no acceptable risk mitigation strategies could be implemented to adequately address these risks.

The contradiction arose because the Council resolution to create the Working Party was raised as a Motion without notice so Council Officers were unable to provide advice on the Motion before it was resolved.

Had the officers been able to provide advice the contradiction could have been removed facilitating a more productive outcome for the Working Party.

The minutes of the Working Party mimicked debate in the Council chamber and in the public arena as membership of the Working Party consisted of members holding both points of view, resulting in a debate focussed on contradicting the evidence supplied by Council Officers, discrediting the independent risk assessments, and rejecting any additional data.

On several occasions comments were made by Councillors that were not aligned with Council resolutions. This enc ouraged protestors in their c riticism of Council’s decisions.

Council’s Media Policy states:

• Council officials should support Council decisions and should refrain from using the media to make negative personal reflections on each other or comments that could be interpreted as such and which are reasonably likely to undermine public confidence in the Council or local government generally.

• As members of the community, Council officials are entitled to enter into public debate and make comment on civic affairs provided they do not give the impression they are speaking in their official position for or on behalf of Council.

Conclusions of the Engagement Processes Review

• A consistent message was delivered to the community and Councillors about Council’s position regarding risk management of trees and the need to remove the trees in Laman Street to ensure public safety.

• An active community campaign opposing the removal of the trees and a reactive approach to communications by Council for the issue resulted in alternative views clouding the overwhelming evidence presented to Councillors and the community.

• It is important to develop and apply appropriate issues management strategies to ensure the community is fully informed about Council activities.

• It is equally important to carefully identify which issues require development of these strategies as the resources required to manage such issues can be quite extensive and may impact on officers’ ability to complete their normal duties.


Recommendations of the Engagement Processes Review The following is not a complete list of the recommendations; rather, it lists the recommendations of interest to other organisations facing the inevitability of renewing cultural plantings as part of sustaining urban forest benefits within a responsible risk management framework:

1. Develop an issues management strategy for issues of major community significance to include: • a dedicated project manager to oversee all activities including engagement with the

community • an appropriate budget to ensure effective engagement activities are supported

• an appropriate overarching community engagement plan as part of an overall project plan 2. Develop strategies to better utilise social media to introduce and manage issues 3. A directive stating that issues of major community significance, that are also identified as posing a

high risk to safety, should be clearly communicated so that the community can be informed on the issues at hand and councils response. However community consultation in such matters would not be required as this would provide an expectation that the community would be able to provide feedback on an operational issue

4. Develop an Engagement Framework and an awareness campaign on the differing levels of public participation, based on the IAP2 spectrum.

The Path ahead – intergenerational equity - sustaining the urban forest In June 2012 Council adopted a design for renewal of the Laman Street cultural precinct. Work, commencing in September 2012 includes construction of extensive load bearing root vaults as the foundations for establishing an avenue of purpose grown Hills Figs. The trees will define a people friendly cultural heart to Newcastle. The estimated construction cost of $1.8 million is an investment in a long-term vision founded on the principle of intergenerational equity.

Dr Greg McPherson (2) Director of the Centre for Urban Forest Research, California, touched on the essence of the Laman Street issues, at the end of his 2009 tour of four Australian capital cities, he observed: “The transformation of mature urban forests, from forests of the past to forests for the future, poses problems in many communities. Renewal of the urban forest is particularly complex in Canberra, where the historic quality of its streetscapes is integral to the character of its neighborhoods. Can the emotional debates about tree removal and replacement become a touchstone for broader public understanding and support? “ “The public landscape along streets and in parks is the last vestige of greenspace, and needs to be redesigned for maximum functionality”.

The Laman Street cultural precinct is one such ‘public landscape along a street’ that is being ‘redesigned for maximum functionality’.

Finally, two personal observations from the Laman Street issues The first concerns the public perception of commercial arboriculture. Throughout the life of the Laman Street issue a community group opposing the removal of the trees engaged a number of commercial arborists to give their opinions about Council’s risk assessments and reporting.

Despite Council’s extensive and readily accessible technical reporting detailing the investigations, the facts, the evidence and the findings, commercial arborists contributed the following statements relating to the Laman Street trees :

• “.... there is no evidence that the trees have moved in the slightest or are in anyway structurally compromised.”

• “All of the Laman Street figs are structurally sound” • “No evidence the trees are dangerous and the level of risk is akin to falling out of bed” • ‘‘A blind person can see the trees are structurally sound and in good condition at the moment” • “The level of risk is marginal for several of the trees but many of the trees currently present

virtually no risk as they would fall into an adjoining tree if they were to fail” • “The current root morphology is more than adequate to support the trees to date and there is no

evidence that the trees have moved in the slightest or are in anyway structurally compromised.” • “There has been an assertion that these trees (sic) fig trees pose an abnormal level of risk yet to

date all evidence suggests otherwise.”


• “To date there is no quantifiable evidence that suggests that these trees have a greater risk of failing.”

These and many more such statements contained in tree reports and media statements provided by community groups and prompted a Council officer to ask, “What do you call a group of arborists?” “A controversy!”

This sentiment was echoed during the December 2010 Public Voice hearing when a Councillor said, “I’ve been very much reliant upon reports and I’ve read very many reports on this matter. What I’ve learnt from those reports is that arboreal science is far from being exact and you can get somebody to write your report to support your point of view regardless of what it happens to be.”

These comments should ring alarm bells for all arborists and arboriculture organisations as they suggest the industry has a professional credibility problem that risks ‘tarring us all with the same brush’.

The complexity of information, the statutory framework, the political and social circumstances and the dynamic nature of the Laman Street trees gave decision-makers (elected and administrative) a monumental task. In the end it boiled down to judging the credibility of arborists and the veracity their information. With statements like those quoted above, perhaps their task was made that much easier?

My second observation is that those concerned with identifying defects and assessing their connective significance with respect to cultivated Hills Fig, should find Dennis Marsden’s 2006, 2007 and 2009 reporting on the Laman Street trees a very useful resource. His reports detail and discuss symptoms and defects contributing to Hills Fig failures in Newcastle. These include the cluster wedge, the ‘I’ beam formation, bark inclusion, compression forks, notch defects, root plate linearity and crown asymmetry.

Dennis made the following observation on the assessment of trees such as Hills Figs growing in streets and other highly developed urban spaces:

“In assessing the subject trees, we are not dealing with trees that fit neatly into test book examples of horticultural ideals and well defined defects, rather, we are dealing with a departure from the ideal and the departure takes us out of the text books and into the grey areas that are neither perfect nor so far in the opposite direction to perfect that tree removal is instantly and unequivocally warranted” (3)

This observation points to the challenge facing arborists responsible for managing large, ageing trees in confined concrete and asphalt street environs.

References The City of Newcastle, 2012 Review of Laman Street Engagement Processes http://www.newcastle.nsw.gov.au/ data/assets/pdf_file/0019/187003/Laman_Street_Report_-_Final.pdf

McPherson G. E., 2009 Observing Urban Forests in Australia. Arborist News, International Society of Arboriculture, USA http://www.fs.fed.us/psw/publications/mcpherson/psw_2009_mcpherson001.pdf

Marsden D (2007) Assessment of Hill’s Weeping Fig Ficus microcarpa var. hillii In Civic Cultural Precinct, Laman Street , Cooks Hill, Newcastle The Sugar Factory, Australia http://www.newcastle.nsw.gov.au/ data/assets/pdf_file/0012/100092/Marsden_report_2.pdf

Sources of further information Council decisions on Laman Street: http://www.newcastle.nsw.gov.au/environment/tree_management/laman_street_figs/council_decisions

Key documents on the Laman Street Trees: http://www.newcastle.nsw.gov.au/environment/tree_management/laman_street_figs/key_documents

2006 report on Laman Street tree root plate architecture by Dennis Marsden:


http://www.newcastle.nsw.gov.au/__data/assets/pdf_file/0019/187003/Laman_Street_Report_-_Final.pdf

http://www.newcastle.nsw.gov.au/__data/assets/pdf_file/0019/187003/Laman_Street_Report_-_Final.pdf

http://www.fs.fed.us/psw/publications/mcpherson/psw_2009_mcpherson001.pdf

http://www.newcastle.nsw.gov.au/__data/assets/pdf_file/0012/100092/Marsden_report_2.pdf

http://www.newcastle.nsw.gov.au/__data/assets/pdf_file/0012/100092/Marsden_report_2.pdf

http://www.newcastle.nsw.gov.au/environment/tree_management/laman_street_figs/council_decisions

http://www.newcastle.nsw.gov.au/environment/tree_management/laman_street_figs/key_documents

http://www.newcastle.nsw.gov.au/ e_Arch_Sugar_Factory.pdf

data/assets/pdf_file/0009/100071/0612Investigation_Report_Root_Plat

2009 report on the Laman Street trees by Dennis Marsden: http://www.newcastle.nsw.gov.au/ al.pdf

data/assets/pdf_file/0014/100067/090807Assmtfigslamandmarsden_fin

Response to engineers presentation on Laman Street trees: http://www.newcastle.nsw.gov.au/ n_19_July_2011.pdf

data/assets/pdf_file/0009/179163/Response_to_engineers_presentatio

2011 Newcastle Herald article on the political background to the Laman Street fig tree issues. http://www.theherald.com.au/news/local/news/general/figs-expose-relations-between- councillors/2302042.aspx?storypage=0


http://www.newcastle.nsw.gov.au/__data/assets/pdf_file/0009/100071/0612Investigation_Report_Root_Plate_Arch_Sugar_Factory.pdf



http://www.newcastle.nsw.gov.au/__data/assets/pdf_file/0014/100067/090807Assmtfigslamandmarsden_final.pdf



http://www.newcastle.nsw.gov.au/__data/assets/pdf_file/0009/179163/Response_to_engineers_presentation_19_July_2011.pdf



http://www.theherald.com.au/news/local/news/general/figs-expose-relations-between-councillors/2302042.aspx?storypage=0

http://www.theherald.com.au/news/local/news/general/figs-expose-relations-between-councillors/2302042.aspx?storypage=0

Appendix 1 – City of Newcastle - Media Release – 25 January 2012


Appendix 2 – City of Newcastle - Web Release – 17 January 2012 Fig forum light on facts Last night's fig fact forum included a number of statements that were false. These are addressed below. • Council as a public body is proud of its openness and transparency in this matter. All relevant information

(except where privileged) has been put before Council and the community. Council has conducted workshops, open forums, public voices, open Council meetings and provided information to interested parties through correspondence and Government Information (Public Access) Act requests. The vast majority of the information available is on our website.

• Council did not withhold the RADAR report from Caity Raschke nor doctor it as Dr Raschke claimed in her opening statements. Council processes all requests for information in accordance with the Government Information (Public Access) Act. All requests in relation to the RADAR report were processed in accordance with these obligations and the RADAR reports provided. It is offensive to accuse council of doctoring a report.

• Council has already obtained four independent assessments by expert arborists on the Laman Street figs and they all support the findings that the risk to public safety and property is foreseeable and not insignificant.

• Due to the huge body of evidence supporting the safety risk, Council's insurer Statewide Mutual will not cover the figs beyond 31 January 2012. Council's broker has canvassed the global insurance market and no other insurer worldwide is prepared to indemnify Council for loss caused by the figs.

• Council is bound to provide an accurate assessment of risk to the insurer and we believe we have done so. Statewide made its offer to fund dynamic testing before it reviewed any existing information relating to the trees and revoked its offer after receiving Council's reports. Council has given its Insurers both Council reports and those provided by Save Our Figs (SOF) to the Laman Street Working Party.

• Statements that claim the trees are safe as evidenced by "looking out the window" are extremely irresponsible. A statement made that the level of risk of a tree failure is the same as falling out of bed is also irresponsible. Further comments made about public utilities, public liability and professional indemnity insurance indicate a limited knowledge or understanding of tree management in the urban context. Over the past 10 years, 35 Hill's figs out of 135 in the inner city have failed or been removed as a foreseeable risk. That's just over one in four.

• Council's comment on the risk assessment by Mr Mike Ellison was released last night prior to the Fig Forum. However, there seems to be discrepancies between the risk assessment in the report and comments attributed to the author in the media. The difference is an order of magnitude which is of concern.

• Any suggestion that the Anzac Centenary submission to the National Commission (made in September 2010) is behind the removal of the figs is a conspiracy theory. The Anzac Centenary submission was an ideas submission only and NOT an application for funding. This is clearly stated on the Anzac Centenary website. It is illogical for this idea to be the reason for removing the trees when no plans have been exhibited, approved nor funding received. Secondly, the submission was made at a time when there was a resolution to remove and replace the trees. The submission clearly states the figs trees are being replaced, not removed to make way for a "plaza". The submission also says Laman Street could become a cultural gathering place beyond its present function as a roadway. It never suggests that this would be at the exclusion of new fig trees. Thirdly, every single piece of concept artwork in the submission includes fig trees planted in Laman Street.

• None of the inspections, investigations, analysis, consultations, forums, working parties and reporting by Council on the Laman Street fig trees has anything to do with any proposal to construct an Anzac Memorial or underground carpark.

• Work done in providing a restraint system for the Lone Pine within the Memorial Grove is an example of proactive tree management in light of the exposure this tree will receive when the Laman Street fig trees are removed. Propagation of seeds from the Lone Pine are underway.

• A statement made at the forum that this is the first time the Roads Act has been used this way to remove trees is utterly false. Councils all over the State use the Roads Act on a regular basis to remove hazardous trees. Council's decision to remove the trees under the Roads Act was upheld by the Land and Environment Court last year.

• Council's actions in Laman Street do not herald the wholesale removal of street trees across the city. Council undertakes a very detailed and rigorous assessment of its public trees and risk is assessed on a


site-specific, case-by-case basis. In fact, a number of trees that were a significant risk have been removed over the last 10 years.

• Concerns expressed at the forum regarding the necessity for Council to have police protection while undertaking reasonable, lawful removal of the trees was the result of the behaviour of members of Save Our Figs and their supporters and not Council staff. In this matter, Council staff have behaved in a professional manner despite, at times, extreme provocation.

• A detailed response to the presentation Professor Mark Stewart and a colleague of his made to Council last year has been provided on Council's website.

• Although Save Our Figs has often referred to a number of other arborist reports that contradict Council advice, none of the authors of these opinions or reports have entered into a contractual agreement that would make them legally accountable for their opinions. Council's internal reports and externally sourced reports base their opinions on detailed knowledge of the site, evidence-based investigations and readily available relevant literature.

• There is no ulterior motive to remove the trees and suggestions to the contrary are completely unfounded. Council will replant figs in Laman Street and already has replacement trees ready to go. These trees are now nearly four metres high and will be planted in specially constructed vaults to avoid the root problems that have plagued the existing figs.

• Council acknowledges that this issue has become highly contentious for some members of the community. However, it is our responsibility to act in the best interest of the whole community, not just some of its members.

• It is wasteful to spend any more ratepayers' money and resources on pursuing this issue and The City of Newcastle is extremely keen to return its full attention to its core duties as soon as possible.


Flooding following Drought: a Swift and Subtle Killer of Stressed Trees

G M Moore

Burnley College, University of Melbourne, 500 Yarra Boulevard, RICHMOND, 3121 Introduction After the prolonged dry period experienced in south-eastern Australia from 1998-2010, large numbers of trees suffered significant stress in both urban and their natural environments. Many older and stressed exotic and native trees, including large numbers of river red gums, plane trees and conifers, such as pines and cypresses, died.

The last two years, 2010-11 and 2011-12, have seen La Nina climatic events with their associated higher than average rainfall affecting the previously dry part of the nation. In many places floods have replaced drought as a major concern. Many trees have recovered brilliantly from the stress caused by the long dry period – many eucalypts and elms have been spectacular in their re-foliation and growth.

However, it has become evident that some trees and some species have continued to decline, and in some cases trees that had survived the long dry period succumbed in the wetter months. The question has been raised as to why these trees have died during the “good times’ when they had coped with such a long period of stress. Perhaps the answer lies in an understanding of the subtle and lethal effects on trees of flooding, waterlogging and low levels of soil oxygen, especially after a long dry period. It is not uncommon for a second dose of stress to kill trees that have survived a previous bout of stress.

Some Relevant Basic Root Anatomy In most urban trees, the root system consists of a root plate consisting of structural and absorbing roots which are often only 200-300mm deep (Figure 1), from which descending roots (also called vertical or sinker roots) emerge and go to deeper soil depths of 500-1000mm or, in some soils, deeper (Moore, 2008). The fine absorbing roots, usually predominantly in the root plate, produce very delicate root hairs that extend from epidermal cells and non-suberised feeder roots at the zone of elongation, just behind the root cap and tip. The root hairs are very fine and increase the absorbing surface area of the root system enormously. They are responsible for most of the nutrient and water uptake. Being in the upper 200-300mm of the soil profile, they are prone to changes in the edaphic environment, such as water deficits, waterlogging and soil oxygen levels.

The root hairs persist for a very short period of time, frequently a matter of a few days before they are damaged or die off. Without them the surface area of the tree’s root system would be insufficient to sustain its supply of water and nutrients for the basic metabolic processes such as photosynthesis and respiration (Kujawski, 2011). However, in all tree species studied mycorrhizal fungi form symbiotic relationships with the roots. These fungi may grow around the roots and root cells (ectomycorrhizae) or in between and into the root cells (endomycorrhizae). The association between tree roots and mycorrhizal fungi is an intimate mutualistic symbiosis which persists for the life of the tree. The benefits for the tree are that the fungal hyphae increase the absorbing surface area for the uptake of water and nutrients, while the fungus shares some of the carbohydrate that is directed to the root system from photosynthesis in the canopy.

The production, growth and development of fine roots, root hairs and mycorrhizae are influenced by the edaphic environment (May et al, 2012). They both grow well in moist, nutrient-rich, well-aerated soils with a low bulk density, but both can be damaged or killed by dry soil conditions and by flooding, waterlogging or compaction which can lead to hypoxia and anoxia. Hypoxia occurs as soon as the level of oxygen limits mitochondrial (aerobic) respiration, while anoxia occurs when such respiration is halted (Parent et al, 2008).The loss of root hairs or mycorrhizal fungi leads to a reduced root absorbing surface area, which often gives symptoms of wilting and nutrient deficiency, regardless of the cause.


Descending (sinker) roots at drip line

Root plate: Shallow and spreading

Descending roots directly below trunk. Often 100- 150mm in diameter and several to many may occur in this vicinity

Figure 1. Descending or sinker roots typical of urban tree root systems (Modified from Watson and

Neely, 1994)

The mycorrhizal relationship with the host tree is very complex, and there may be a number of different fungal species that can form the relationship with the host, but not all are of equal benefit to the tree. In many cases there will be more than one species of fungi in association with the host roots. Furthermore, the benefit of the fungi to the host is not confined to the increased absorbing surface. The suite of mycorrhizal fungi in association with the host often confers a degree of protection on the host from attack by pathogenic fungi. This protection may come from the mycorrhizal fungi outcompeting potential pathogens and making the root surface unavailable for colonisation, but they may also be actively antagonistic to the pathogens.

If edaphic conditions change through drought, flooding or waterlogging and the mycorrhizal fungi cease growing or are reduced, the protection that they afforded the host may also be diminished. This may be part of the explanation as to why a number of trees succumbed to fungal diseases during and immediately after the long dry period.

Trees and water Water plays a vital role in the life of all terrestrial organisms including plants (Taiz and Zeiger, 2010). Typically the non-woody biomass of plants is composed of between 70 and 80% water (Lambers, Chapin and Pons, 2008) and, in trees, if the water content of cell walls falls below about 78% its effect on tree physiology is such that the tree will be stressed and may die.

Water uptake in trees is predominantly through the intimate contact of root hairs and mycorrhizal hyphae with the rhizosphere where they have direct contact with the soil water over the very large surface area needed for effective uptake. Mature roots are less permeable or impermeable to water because of the development of an outer layer of protective tissue, called exodermis or hypodermis (Taiz and Zeiger, 2010). Woody roots that have undergone secondary growth are incapable of absorption.

Water is taken up by the root system of the tree, which can be seen as the supply system and passes through the living (symplast) and inert (apoplast) anatomical components of the tree where it can be utilised by cells for metabolism as it passes or is transported through the xylem tissues or as part of the phloem transport to the foliage. Once in the leaves, the water evaporates from the surface of the leaf cells into the surrounding atmosphere mainly through stomatal apertures. The combined evaporation of water and its metabolic use constitute the demand side of the tree’s water balance equation.

While the role of water in transpiration is often well understood by those managing trees, its roles in osmoregulation and metabolism are often forgotten. The availability of water can significantly impact on the uptake of nutrients, the transportation of metabolites and the efficiency and effectiveness of basic physiological processes, such as photosynthesis and respiration. Tees cannot survive and grow without


e stress scenar

be applied to

ose model that

assimilating carbon dioxide, which makes them vulnerable to drought because it is inevitably accompanied by loss of water through transpiration (Pate and McComb, 1981).

Water stress can occur through either too little or too much soil water, both of which can reduce the rates of physiological processes, such as photosynthesis, respiration and protein synthesis (Lambers et al, 2008). Drought, flooding and waterlogged soil can have profound effects on energy (ATP, the energy rich molecule of cellular metabolism) production, the availability of oxygen and carbon dioxide and the efficiency of plant metabolism, all of which impact on plant growth, development and survival.

Effects of Prolonged Dry Periods (Drought) For the purposes of this paper, the term drought refers to a period of time over which the water content of the soil is reduced by inadequate precipitation to an extent where plants suffer from a lack of water sufficient to disrupt normal life processes (Larcher, 1995; Coder, 1999). Drought is a common environmental stress that may damage trees directly by severe seasonal drought, or damage may be cumulative over several consecutive years (Schoeneweiss, 1986). Droughts may occur over one or a couple of years and may be described as acute, but those where rainfall is below average over longer periods of time, such as those which affected South Australia and Victoria at the turn of the nineteenth and Twentieth centuries (sometimes referred to as the Federation drought) and that besetting south-eastern Australia from 1997-2010 are chronic droughts with below average rainfall year after year (Moore, 2009).

Chemical Concentration

Number of Doses Dose Duration of Dose

Environmental Factors:

Plant Tissues

Plant Characteristics:

*Climate *Genotype *Edaphic *Age *Biotic *Active/Dormant

Effects

Figure 2. The d Acute

can Chronic

multipl Subtle

ios, including period of water deficit followed by flooding, waterlogging and hypoxia and anoxia.

Figure 1: The effects of chemicals on trees depends on the dose and its interaction with eInnvtihreoncumrreentaelrafaocftcolirms aatnedchtahnegechaanrdaucntecerirstatiinctsy,oift itshneopt lkannotw(nafwtheertMheor othre,p1ro9lo8n3g)e.d dry period is a drought and part of a regular natural pattern that occurs over a longer period of time. It might be the one in five hundred year or perhaps the once in a millennium drought for example, but current meteorological data are too recent to reveal such patterns. However, it could be a dry period that introduces a more permanent climate change with lower rainfall. It can only be decided when data are analysed in future and it may take 15- 20 years before the answer is known.


During a long period of below average rainfall, trees are subjected to a chronic rather than acute period of water stress (Figure 2). There are a number of ways in which trees can respond to such conditions (Coder, 1999):

• close their stomata, which conserves water but impacts on transpiration and aspects of • plant metabolism such as photosynthesis and respiration • production of the stress hormone Abscisic Acid (ABA) • show signs of wilting • increase their root to shoot ratio by extending their roots system • exploiting a greater soil volume and providing a greater opportunity for water uptake • shed foliage, and even limbs, as a way of adjusting foliage surface area to the reduced • water availability • altering their osmoregulatory environment by adjusting internal solute concentrations • modifying turgor pressure (Figure 3)


DRY PERIOD

(DROUGHT)

WATER DEFICIT

Stomatal Closure

Reduced Photosynthesis

Reduced Carbohydrate

Reduced Mycorrhizal Growth, and absorptive surface area

Reduced Root Growth

Internal water, energy and nutrient deficits

Increased vulnerability to fungal attack

Tree decline

TREE DEATH

Figure 3. Some of the major effects of water deficit (drought) on trees.


Perhaps the best known response of trees, and plants in general, to low water availability and drought is complete or partial stomatal closure, which often occurs in the early stages of water deficit (Kujawski, 2011; Coder, 1999). This closure can be precipitated by the direct hydraulic effects of water scarcity, but often long before leaves wilt, the stress stimulates the production of ABA (Lambers et al, 2008). ABA is often described as the stress hormone and its synthesis from carotenoids can be triggered in the roots (Moore, 1998; Lambers et al, 2008). The hormone stimulates responses in other parts of the trees, one of which is stomatal closure in leaves (Larcher, 1995; Kujawski, 2011).

ABA is a significant hormone produced by roots in contact with drying soils. Soil drying increases the concentration of ABA in the xylem sap as well as in the leaves (Lambers et al, 2008) and as a consequence there can be a rapid stomatal closure which minimises water loss (Taiz and Zeiger 2010). It has been postulated that roots might sense drying soils because of ABA release into the soil (Lambers et al, 2008). Abscission of leaves is a significant long term adjustment that improves the trees chances of survival and results from enhanced synthesis of ethylene (Taiz and Zeiger, 2002). Leaf shedding in eucalypts is often observed (Pook, 1984) and reduces both transpirational surface area and photosynthetic activity. However, when water becomes available many eucalypt species re-foliate rapidly and photosynthetic activity is restored.

With a focus on water conservation, stomatal closure by plants is usually seen as an efficient and effective response to water scarcity. However, it can come at a significant cost as the closure impacts on photosynthetic activity as carbon dioxide uptake is reduced, which then affects other metabolic processes (Kozlowski, Kramer and Pallardy, 1991). In some situations and for some species not all stomata will close. Trees that reduce stomatal conductance in the middle of the day may only close some of their stomata, whilst others remain open allowing uptake of carbon dioxide for photosynthesis (Lambers et al, 2008). Stomatal responses corresponding to pre-drought conditions may not occur for a long period after rehydration (Coder, 1999).

As soils dry the tree may make osmotic adjustments either by taking more nutrients from the soil or by releasing more sugars (Lambers et al, 2008). Taking up more nutrients is difficult as the soils are dry and so the uptake of ions in solution is low and to increase the uptake would require extra energy. This is also difficult as photosynthetic activity has diminished due to complete or partial stomatal closure. However, most trees if they have not been stressed for too long have significant starch reserves stored in root cells, and also in the trunks and leaves.

If a tree has closed its stomata as a response to drought it can use carbohydrate stored as starch as a substrate for the maintenance of normal respiratory metabolism and function, provided there is sufficient gaseous exchange. Starch is readily broken down by amylase enzymes into its constituent glucose molecules. These not only provide a substrate for respiratory metabolism, but also a solute that helps maintain osmotic and water potential and osmoregulation within the tree and are part of the tree’s response to drought stress. In making these osmotic adjustments, the tree can maintain cell turgor as the water potential of the soils decrease as they dry, which may allow the tree to take up more water in drying soil.

Drought also has a significant effect on turgor pressure which is not only affected by osmoregulatory components such as water potential but also by the level of cell wall elasticity. The more elastic the cell walls, the more water cells can hold and the longer the tissues can maintain turgor under water deficit. The loss of turgor can affect plant transport, but effects on osmoregulatory processes impact on cellular metabolism such as photosynthesis (Lambers et al, 2008). Turgor is lost when the hydrostatic pressure in the cell sap falls below atmospheric pressure and the cell walls collapse (Taiz and Zeiger, 2010).

Whether a tree reaches the turgor loss point can depend on the cell wall elasticity. Cell walls can be made more elastic by the actions of hormones such as auxins and ethylene (Taiz and Zeiger, 2010). The production of ethylene can be stimulated by the increased level of ABA. Trees may make the cell wall softer over a period of weeks. The adjusted elasticity allows transpiration to continue for longer before there is a loss of turgor, which permits metabolic processes such as photosynthesis to continue. While each cell may only hold a small amount of extra water, trees contain a great many cells and so the little bit of extra water in each cell might be the difference between the loss of turgor and survival.

Fine root growth occurs in spring and is dependent on soil moisture content. Water deficit in spring means that trees may not have been able to produce new fine roots for several years, which leads to a decline in root


system health (May et al, 2012). Furthermore, under severe water deficit, the water tends to pull away from the surface of the fine absorbing roots (Kujawski, 2011) creating a gap which interferes in the continuum between the soil, plant and atmosphere. If the plant continues to lose water in transpiration then the water is drawn from root cells causing shrinkage in the membranes and exacerbating the gap.

The overall effect of drought on a tree can be profound. Leaves tend to be smaller and thicker, xylem vessels are smaller, and the root:shoot ratio increases (Harris, Clark and Matheny, 2004). Drought can affect photosynthesis for weeks or months depending on the extent of the drought (Kozlowski et al, 1997). Foliage symptoms of water stress include, bending, rolling, mottling, scorching, chlorosis, and shedding of leaves as well as early autumn coloration. It may also cause dieback of twigs and branches in the extremities of the tree crowns (Coder, 1999). The width of growth rings for drought years will be narrower, because cambial growth slows or accelerates with rainfall. Furthermore, last season’s supply of growth material and resources limits the current year’s growth, so this year’s drought will effect next year’s cambial growth (Coder, 1999). So when water becomes limiting, tree growth is stunted.

Trees take time to recover photosynthetic activity and from permanent damage to stomata and root tips (Coder, 1999; Parent et al, 2008) and so become more prone to insect and disease attacks (Stolzy and Sojka, 1984). Drought stress can decrease resistance to trunk-invading organisms such as wood borers, bark beetles, fungi, and vascular diseases (Schoeneweiss, 1986). This is typically described as secondary attack, where opportunistic fungi and insects, among them boring insects and bark beetles, attack trees weakened by water stress (Schoeneweiss, 1986; Iles & Gleason, 2008). Drought also limits nutrient availability by preventing the absorption of essential nutrients. The tree may actually succumb 2 or 3 years later to what may have been considered an innocuous secondary infection or stress.

Effects of Flooding and Waterlogging Tree roots require aerated soil so the effects of flooding, even what might be considered short term inundation, can be injurious to trees (Schoeneweiss, 1986). Soil oxygen is displaced by water and the diffusion coefficient of oxygen in water is approximately 10,000 times lower than in the air, giving rise to hypoxia and anoxia (Niki, Takahashi and Gladish, 2011). If the water is not moving, the rate of diffusion can be even slower and the amount of dissolved oxygen in still water may fall to as little as 3% of that of a similar volume of air. This oxygen is rapidly used by respiring roots and aerobic microorganisms (Martens-Mullaly, 2012). The impact of anoxia can be quite rapid, with the roots of some tree species starting to die within a few hours of being exposed to anaerobic conditions (Pallardy, 2008).

As in waterlogging, flooding leads to a reduced soil aeration which can result in tree roots respiring anaerobically (Figure 4). Not only is anaerobic respiration much less efficient than aerobic respiration in terms of ATP and energy production (approximately 5% as efficient), but it also produces lactic acid or ethanol, both of which are phytotoxic (Coder, 2011; Pallardy, 2008). These can kill delicate root cells containing root hairs and also reduce the growth of mycorrhizal fungi that are associated with all tree root systems.

The reduced energy output from anaerobic respiration may sustain a tree for short periods of time, but it consumes the carbohydrate reserves of the root tissues. If the period of waterlogging, flooding or anoxia extends over a long period of time, it can deplete these reserves completely (Figure 5). This effectively starves the root system and there is a cessation of root tip growth as root tip elongation requires oxygen (Pezeshki, 1991). Many tree species that are tolerant of flooding continue to undertake glycolysis for the production of energy, but they must have substantial carbohydrate reserves to survive. Furthermore, many plants switch metabolism to the production of about 20 anaerobic stress proteins (ANPs) that enable energy generation independent of oxygen availability when oxygen is limiting.

The loss of fine roots, root hairs and perhaps more importantly mycorrhizal fungi can have a profound impact on the trees capacity for absorbing water and nutrients. This can manifest itself in the tree displaying symptoms that are very similar to those of drought – wilting, leaf chlorosis and leaf shedding. The reason for these symptoms is the loss of absorbing surface area. This scenario often leads home gardeners, and even professionals who have failed to check soil moisture conditions, to apply water to already stressed trees in the mistaken belief that they are suffering from a lack of water.


GLUCOSE

Hypoxia/Anoxia (Low soil oxygen) Adequate Soil Oxygen

Little ATP (2) and Heat produced

Lots of ATP (38) and Heat produced

ETHANOL

OR

LACTIC ACID

OXYGEN &

CARBON DIOXIDE

Figure 4. Aerobic and anaerobic respiratory metabolism. Under hypoxic and anoxic soil conditions, ethanol and lactic acid are produced both of which are phytotoxic.


FLOODING

Soil Compaction

Silt deposition (fill) Changed microfauna

Changed microflora Phytotoxic products

* Ethanol

* Lactic Acid

* Hydrogen sulphide

* Carbon dioxide

* Ethylene

* Methane

* Nitrogen

* Sulphur

Oxygen Deficiency Altered soil pH

METABOLIC

MODIFICATIONS Changed Energy status due to reduced

* Aerobic respiration

* ATP Synthesis

* Photosynthesis

* Carbohydrate Reserves

PHYSIOLOGICAL MODIFICATIONS Internal water deficit due to reduced

* Stomatal aperture

* Hydraulic conductivity

* Root permeability

* Root surface area

* Mycorrhizae

ADAPTIVE

RESPONSES

Anaerobic Respiration

* Ethanol

* Lactic Acid

* Reduced ATP

ANPs Synthesis ABA Synthesis

MORPHOLIGICAL

& ANATOMICAL RESPONSES Suberised Endodermis

Aerenchyma

Hypertrophied lenticels

Adventitious Roots Increased cell wall

elasticity

Figure 5. The effects of flooding on soil and some of the metabolic, physiological, morphological and anatomical modification and responses of trees (modified and extended from Parent et al, 2008).

However, it should not be forgotten that flooding, water-logging and anoxia can also lead to high levels of ethanol, lactic acid, hydrogen sulphide, carbon dioxide, ethylene, methane, nitrogen, sulphur and cyanogenic compounds in soils, some of which are toxic to trees or influence plant growth and function (Martens-Mullaly, 2012; Iles and Gleason, 2008). The longer the period of inundation persists, the poorer the soil conditions and the more rapidly and significantly the health of the tree deteriorates.

Trees that have been flooded may be more prone to windthrow and total tree failure because of the loss of root mass. Furthermore, if the soils remain wet, soil strength is diminished and combined with a loss of root mass, tree failure in strong winds is more likely. This situation can be made worse by the deposition of a layer of fine silt and mud by flood waters (Iles and Gleason, 2008), which like any fill placed over the root system can stress a tree due to changes in the edaphic environment. The strong currents and soil particles suspended in flood waters can erode soil from the base of trees, exposing tree roots, which are then more vulnerable to drying, mechanical injury and windthrow (Iles and Gleason, 2008).


FLOODING

Hypoxia/Anoxia Compaction/Erosion

Anaerobic Respiration

Reduced carbohydrate and reduced energy (ATP)

Ethanol/Lactic Acid/Soil Phytotoxins

Reduced Root Growth


Internal water and energy deficits

Increased vulnerability to fungal attack

Tree decline

TREE DEATH

Figure 6. Some of the major effects of flooding and waterlogging that lead to hypoxia and anoxia of trees.

Flooding that leads to soil anoxia and anaerobiosis adversely affects the shoot growth of trees by inhibiting internode elongation and the formation and expansion of leaves. Flood induced chlorosis can lead to premature senescence and abscission (Kozlowski, Kramer and Pallardy, 1991). Experiments with potted plants showed reduced height and growth in many flooded conifers and broad leaved trees (Kozlowski, Kramer and Pallardy, 1991). The effects of flooding on growth are not just due to the effects of oxygen. Mineral uptake can be reduced (Kozlowski, 1984) as a consequence of the decline in active transport due to the reduced rate of respiration and roots may lose minerals by leaching (Pallardy 2008). As for most environmental stresses, flooding during the growing season when there is active tree growth is more harmful to trees than flooding during dormant periods (Figure 6). During the growing season and over


summer, higher soil temperatures can also result in more rapid changes in soils that also impact upon root and tree growth. Trees weakened by flooding stress are also prone to secondary infections by fungi, such as cankers and insects (Iles and Gleason, 2008).

Flooding following Drought The compounding effects of different stresses on tree health are well documented (Moore, 1999). Trees may survive one environmental stress, but often succumb to a second dose of stress that might be applied simultaneously or sequentially. The dose model that considers the level of a particular stress, its duration and the number of doses in relation to the plant and its environment (Figure 2) is useful in considering this phenomenon (Moore, 1999). In southeastern Australia, the long period of below average rainfall was followed by a period of higher than average rainfall that exposed many trees to waterlogging, flooding or anoxia. Thus there is double dose of stress, and the following scenario may have unfolded (Figure 7):

Long Dry Period (drought):

• Over the long dry period (13 years) many trees were significantly impacted by water stress. As a consequence root growth was reduced and in many instances fine absorbing roots and absorbing surfaces were reduced

• The period of water stress also led to the depletion of root carbohydrate reserves as stomata were closed or other tree responses to dry soil conditions reduced or modified photosynthetic and respiratory metabolism

• Mycorrhizal growth also diminished due to the combined effects of the low soil water and a lack of carbohydrate supply from the stressed tree symbiotic partner

• The loss of fine absorbing roots and mycorrhizal associates rendered the trees prone to greater stress as the dry period extended and some of the plants died

• The loss of root carbohydrate reserves also delayed new root production when water became available as root growth was dependent on renewed photosynthetic activity

• Furthermore, the diminished mycorrhizal fungal populations associated with the trees rendered them susceptible to pathogen and other fungal attack as the defensive role played by the mycorrhizal partners was reduced

• Trees were then dying from fungal diseases, some of them rare and previously undescribed, after several years of below average rainfall

Coincident with the occurrence of the two La Nina years was an above average rainfall. This brought relief for many stressed trees and they recovered rapidly with restored canopies and leaf area indices. However, to the surprise of many people, some trees that had survived the dry period for over a decade died in the wetter and apparently better conditions. Perhaps the following scenario may explain these observations:

Flooding, waterlogging or hypoxia and anoxia:

• Stressed trees begin to regrow fine absorbing roots and mycorrhizal partners resume growth when soil moisture increases after the dry period

• The loss of root carbohydrate reserves delayed new root production when waterbecame available as root growth was dependent on renewed photosynthetic activity

• However, some trees with insufficient time to recover fine absorbing roots or the normal mycorrhizal density, experience waterlogged soils, flooding or periods of soil hypoxia and anoxia. They experience a second dose of stress

• These already stressed trees further deplete their carbohydrate reserves and so root growth ceases, water uptake even when water is abundant is reduced and metabolic processes such as photosynthesis and respiration are adversely affected


• The diminished mycorrhizal fungal populations associated with the trees again rendered them susceptible to pathogen and other fungal attack due to the reduced defensive role played by the mycorrhizal partners

• Trees then die from fungal diseases, and other pest attack

SITUATION AT END OF LONG DRY PERIOD (DROUGHT)

Reduced carbohydrate

Reduced Root Growth


Trees in decline

GOOD RAINFALL

Renewed foliage growth

Internal water, energy and nutrient deficits begin to recover

Root growth recommences, but there is a time delay after foliage recovery

New growth provides opportunity for fungal attack

Increased vulnerability to fungal and insect attack during growing season

MANY TREES RECOVER

HIGH RAINFALL

Hypoxia/Anoxia

Reduced carbohydrate and reduced energy (ATP)

Tree decline

Anaerobic Respiration TREE DEATH

Ethanol/Lactic Acid/ Soil Phytotoxins

Figure 7. Some of the effects of a long dry period (drought) followed by flooding/waterlogging that may lead tree death.


Discussion Under the climate change predictions for south eastern Australia, there is likely to be a general decline in rainfall (usually estimated at 10-15%), but the rainfall is more likely to be over late Spring and Summer. This means that the effective precipitation is likely to be less then the raw rainfall figure might suggest due to the higher rates of evaporation. While La Nina events will still occur, it is also likely that southeastern Australia will experience more droughts and prolonged dry periods.

In cities, the higher summer rainfall is likely to lead to local flooding which could affect urban trees through waterlogging and soil hypoxia and anoxia. Furthermore, a compounding factor could be that much of the open space in cities was once swampy or prone to flooding. Such land will be at risk as sea levels rise and with the tidal push back of rivers and streams, this land will be vital in local flood mitigation and stream flow retardation. Thus many local parks and open spaces will be prone to more regular flooding and waterlogging than in the past century, which in turn could impact on tree root systems. Many trees are also going to experience longer, warmer, dry periods followed by periods of high rainfall leading to flooding, water logging and soil anoxia.

Urban tree managers may wish to consider planning for an increased frequency of prolonged dry periods followed by bouts of high rainfall, waterlogging and flooding. Such a scenario could pose a significant threat to the health and viability of trees in those urban landscapes that form part of catchments and flood mitigation basins. Tree selection criteria that include endurance of waterlogging and hypoxic and anoxic soil conditions, particularly over summer would seem prudent. Proper forward planning could minimise the threats to trees in such situations and enhance their prospects of full life spans.

Acknowledgements The assistance of Dr Peter May and Ms E Moore, linguist, in reading the manuscript and making suggestions for its improvement is greatly appreciated. I also acknowledge the contribution of my students in the 2012 Graduate Certificate in Arboriculture, Urban Tree Growth and Function whose questions and essays on a related topic stimulated the writing of this paper.

References Coder K D (1999) Drought Damage to Trees, Warnell School of Forest Resources, The University of Georgia.

Coder C (2011) Advanced Tree Biology: Photosynthesis and Respiration. Outreach Monograph WSFN11-21 Warnell School of Forestry and Natural Resources. University of Georgia.

Iles J and Gleason M (2008) Understanding the Effects of Flooding on Trees, Iowa State University.

Kozlowski T T, Kramer P J and Pallardy S G (1991) The Physiological Ecology of Woody Plants, Academic Press, San Diego.

Kozlowski T and Pallardy S (1997) Physiology of Woody Plants, 2nd ed, Academics Press, San Diego.

Kozlowski T T (1984) Plant response to flooding of soil, Bioscience 34: 162-167.

Kramer P J and Kozlowski T T (1960) Physiology of Trees, McGraw Hill, New York.

Kujawski R (2011) Long-term Drought Effects on Trees and Shrubs, University of Massachusetts Amherst.

Lambers H, Chapin III F S and Pons T L (2008) Plant physiological Ecology 2nd ed, Springer.

Larcher W (1995) Physiological Plant Ecology, 3rd Ed, Berlin, Springer-Verlag.

Martens-Mulla1y J (2012) Floods wreak havoc with trees, Hort Journal Australia, (4), pp.6-8.

May P B, Livesley S J and Shears I (2012) Managing and monitoring tree health and soil water status during extreme drought in Melbourne, Victoria. Journal of Arboriculture and Urban Forestry (in press).


Moore G M (1998) Tree Growth Regulators: Issues of Control, Matters ofManagement,Journal of Arboriculture, 24 (1), 10-18.

Moore G M (1999) The Action of Horticultural Chemicals on Tree Growth and Development, in Gould B J (Ed) Arboriculture in a Changing Environment, p 19-27, New Zealand Arboricultural Conference, Auckland.

Moore G M (2008) Managing Urban Tree Root Systems, Lawry D, Gardner J and Smith S Editors, Proceedings of the Ninth National Street Tree Symposium, Appendix 6, 7pp, University of Adelaide/Waite Arboretum, Adelaide, ISBN 978-0-9805572-0-6.

Moore G M (2009) People, Trees, landscapes and Climate Change, in Sykes H (Ed) Climate Change On for Young and Old, pp 132-149. Future leaders, Melbourne.

Niki T, Takahashi M and Gladish D (2011) Comparison of the effects of flooding vs. low-oxygen, Plant Root, 5, 31-39.

Pallardy, S (2008) Physiology of Woody Plants 3rd edn, Elsevier, Burlington MA.

Parent C, Capelli N, Berger A, Crevecoeur M and Dat J F (2008) An Overview of Plant Response to Soil Waterlogging, Plant Stress, 2(1) 20-27, Global Science Books.

Pate J S and McComb A J (1981) The Biology of Australian Plants, University of Western Australia Press.

Pezeshki S R (1991) Root responses of flood-tolerant and flood-sensitive tree species to soil redox conditions, Trees: Structure and Function 5:180-186, Springer

Pook E. W (1984) Canopy Dynamics of Eucalyptus maculata Hook III, Effects of Drought, Australian Journal of Botany 33(1) 65 – 79.

Salisbury F and Ross C (1991) Plant Physiology, 4th edn, Wadsworth, Belmont. CA

Schoeneweiss D F (1986) Diseases of Trees in the Great Plains, Chapter 40, Environmental stress effects, USDA.

Stolzy L and Sojka R (1984) Effects of flooding on plant disease, in TT Kozlowski (ed.), Flooding and plant growth. Academic Press, New York.

Taiz L and Zeiger E (2010) Plant Physiology, 5th ed, Sinauer & Associates, Sunderland, Mass.

Watson G W and Neely D (1994) Eds. The Landscape Below Ground, International Society of Arboriculture, Illinois.


STUDENT POSTERS

Examination of tree water status of urban trees using thermal imaging

Zijuan Deng1,2, Huade Guan1,2

1 School of the Environment, Flinders University

2 National Centre for Groundwater Research and Training Introduction Identifying water status of urban trees is important not only because it’s an indicator for tree drought tolerance but also useful to improve tree water use management (Jones, 2007). Water stress monitoring is essential for irrigation scheduling to improve water use efficiency (Jones, 2004b). There are various ways to monitor water status of plants including direct indicators such as leaf water potential, stem water potential, soil moisture and also indirect methods such as porometer, thermal imaging etc (Jones, 2007). Among these methods, thermal imaging is a promising low cost large scale measurement method.

Plant leaf temperature is an indicator of water availability. The first non-contact way to measure leaf temperature with the infrared thermometry dates back to 1960’s (Jackson et al., 1981). Later, the method was widely validated and has a popular following (Idso et al., 1981; Jackson et al., 1981). The method (including the recent more advanced thermal imaging technique) has been applied in crops such as tomato, sunflower, cotton etc (Idso, 1982) , grapevines (Jones et al., 2002), and recently in tree crops such as pistachio (Testi et al., 2008) and almond (Gonzalez-Dugo et al., 2012). Thermal imaging has particular advantages for the quantitative analysis of spatial and dynamic physiological information. It is very useful, for example, in application in screening, such as in the selection of stomatal or hormonal mutants (Jones, 2004a), large spatial scale stomatal mapping (Berni et al., 2009) and heterogeneous evapotranspiration calculations (Moffett and Gorelick, 2012).

To convert the absolute leaf temperature to water stress index, the dry reference and wet reference temperatures are needed to represent the "most water stressed status" and "non water stressed status". There are three major ways for the conversion of leaf temperature to a water stress index. The first and also the most direct way is to create the wet reference and dry reference temperatures. For example, a fully irrigated plot is used to represent wet reference and infer the dry reference temperature from the leaf to air temperature –VPD curve (Idso et al., 1981). The second commonly used practice is to spray water on leaves to get the wet leaf temperature, and to apply vaseline to leaves (prevention of transpiration) for the dry reference temperature (Jones, 1999). The data analysis for both treatments is quite easy and straight forward but it is not practical to get continuous measurement over seasons or even days.

Another method which is still developing is to use intra-crown temperature variations as the water stress indicator. The method avoids the need to get the reference temperatures but has one difficulty that the variation of intra-crown temperature is not a monotonic function of water stress. Both the dry and wet end show much smaller variations in trees than those that are under mild water stress (Gonzalez-Dugo et al., 2012) are therefore not directly comparable over days.

Modelling dry and wet leaves provides a third way to normalize the leaf temperature but are only validated during short periods with certain environmental conditions such as clear days, low wind speed etc which are also the same requirements for the first direct method (Guilsard 2009).

Therefore, we targeted the development of a method that could obtain the water stress index for long-term measurements under different environmental conditions. The new method if successful will broaden the application of the thermal imaging in water stress detection. As mentioned previously, most of the studies were conducted in crops and few works were contributed to urban tree species. There is considerable concern about water sustainability in urban planning and the selection of trees for the urban landscape that are particularly drought tolerant. Thus the second aim of this study is to test the application of this method of monitoring on Australian native species in the natural environment. Two monitoring sites were selected at the


*

c

cp

p

-2 -

p

Flinders University campus for this study. At the first site we set an experiment on a roof top to obtain the wet and dry reference temperature of artificial leaves and at the second site in the University grounds, we concurrently measured the leaf temperatures and the stem water potential of Acacia pycnantha.

Methodology We first set out to test a method for obtaining wet and dry reference temperatures continuously with a minimum of effort. We selected a material (wick) that could absorb water quickly and provide it continuously to the artificial leaves. The wick was supported by steel wires with one end connected to a bottle of water and the other end wrapped with leaf shaped cotton, filter paper, dry leaves taken from a tree, or no wrapping at all. The leaves were put in the bottles at different times, and the difference in degrees of wetness (water stress) was captured by the thermal imaging camera at the same instant (Figure 1). The filter paper leaf was saturated at the outset of the thermal imaging process and was thus used as the wet reference leaf. The dry leaf that was detached from a tree and could no longer transpire was used as the dry reference leaf. Figure 2 shows the experimental set up in the natural environment in the University grounds.

wet leaf

filter paper

wick

dry leaf

real dry leaf

cotton

Figure 1: Experimental setup in the laboratory for wet and dry leaf

The water stress index (crop water stress index (CWSI) (IDSO et al., 1981)) was calculated as

CWSI = (Tc (Tdry

� Ta ) − (Twet � Ta ) − (Twet

� Ta ) � Ta )

(1)

where Tc is the absolute plant canopy temperature or leaf temperature, Twet is the wet reference temperature

when the plant is with fully water availability, Tdry is the leaf temperature when leaf was not transpiring,T a is

the air temperature which should be obtained surrounding the respective leaves but was usually assumed to be the same between the dry leaf site and wet leaf site. CWSI near to 0 indicates that the plant is under no water stress; while values near to 1 show that the plant is under water stress. Theoretically, based on energy balance and the Penman-Monteith equations, the dry and wet reference temperatures can be modelled (Jackson et al., 1981). The equations were used only to show the influencing factors on the leaf temperature such as net radiation R n , vapour pressure deficit ( ec − ea ) and wind speed (influencing the aerodynamic resistance ( ra )) etc.

Tdry

� Ta = ra Rn ρc

(2)

p r R γ *

e* − e T − T = a n ⋅ − c a , γ * = γ (1 + r / r ) (3)

wet a ρc ∆ + γ * ∆ + γ * cp a

Where Tdry ,Twet

,T a have the same meaning as Equation 1. Rn is the net radiation on the leaf surface (W m s 1), ρ is the density of air (kg m-3), c is the heat capacity of air (J kg-1 ◦C-1), γ is the psychrometric constant (Pa

◦C-1), ∆ is the slope of the saturated vapour pressure-temperature (Pa ◦C-1). e* is the saturated vapour

pressure at leaf temperature and ea is the vapour pressure of the air (Pa), ra is the aerodynamic resistance (s

m-1), and r is the potential stomatal resistance of a well irrigated plant which is close to but not actually 0


a

(Jackson et al., 1981). We have assigned 0 by assuming that the evaporation on wet leaves is similar to that on a free water surface. That is confirmed to be reasonable because all the leaf temperatures converged to be almost the same when saturated (Figure 3). Therefore Equation 3 is reduced to Twet � Ta = [ra R n ⋅ γ − ∆(Tc � T )

] − 1 • VPD

(4)

ρcp ∆ + γ ∆ + γ ∆ + γ When under a relatively stable environment, it can be seen from Equations 2 to 4 that the temperature difference between dry temperature and air temperature (Tdry − Ta

) is roughly the same while the difference between wet leaf and air temperature (Twet − Ta

) becomes a linear function to air vapour pressure deficit (VPD ) with a slope of 1 /(∆ + γ ).

ibutton (measure air temp at the canopy)

Stem psychrometer (measure stem water potential)

Thermal image

Figure 2: field experiment on Acacia tree with thermal imaging and stem psychrometer Results and discussion The artificial leaf data was collected on 17th Feb, 2012. One half hour of data (during 12:30 to 13:17) was missing because of a battery power down (Figure 3). The trend of wet and dry temperatures followed the diurnal mode because of radiation but dry reference temperatures showed a higher fluctuation than the wet reference leaf temperature. From 9 to 11 am, both the cotton leaf and wick leaf were close to saturated with CWSI near to 0, but after 2:30 pm as the water level in the bottle lowered and became disconnected from the wick leaf; the CWSI value approached 1. It was also demonstrated that the dry part of the artificial wick leaf reached higher temperatures than the genuine dry leaf while the wet parts of the leaf kept stable regardless of the leaf materials as long as they were fully wet. The results indicate that using wick leaf cannot represent the energy balance of the genuine leaves that are not transpiring, while, the wet leaf temperature (Figure 4) is


Tem

pera

ture

Twet

-Ta

(C)

CW

SI

reliable to use compared to Equation 4; the slope of the graph (0.0052) is near to the value of 1 /(∆ + γ ) under average air temperature during the experiment.

45 T

w et 40 T

dry T

w ick(w et) 35 T

cotton(w et)

2

1.5

stress of wet part(cotton) stress of wet part(wick) stress of most part(cotton) stress of most part(wick) stress of second most(cotton) stress of second most(wick)

30

1 25

20 0.5

15

0

10 09:17 11:17 13:17 15:17 16:17

09:17 11:17 13:17 15:17 16:17

Figure 3. Artificial leaf temperatures over the day (left), normalized thermal index -CWSI (right) note: the symbols of "wet", "dry", "wick", "cotton" correspond to the temperature of leaves referred to in figure 1. "most part" means the dominant temperature (most pixels) of the leaf, the second most is the second frequent temperature based on temperature histogram of pixels.

2 data 1

0 linear

-2 y = - 0.0052*x + 2

-4

-6

-8

-10

-12

-14

500 1000 1500 2000 2500 3000 VPD(Pa)

Figure 4. Differences of wet reference temperature and air temperature versus the vapour pressure deficit

Thermal images at leaf scale resolution were taken from 6th to 27th of Jan, 2012. Most of the days were clear or mostly clear. As we can see from figure 2 to 4, the leaf to air temperature difference can be influenced by environmental conditions. Thus it's practical to compare the temperature difference at the same time of the day when the radiation, wind speed etc were most likely similar. When compared to the direct water stress indicator-the stem water potential, it's quite easy to observe a good correlation with the stem water potential. The best correlation (R2=0.8) of the day occurs between 14:30 to 15:00 pm. The reason could be that the air temperature or vapour pressure deficit reaches their maximum during the day in January when the plant is under largest water stress of the day. It’s mentioned that the method is better performed in drier (higher VPD ) conditions (Idso et al., 1981).


Tc-T

a(C

) Tc

-Ta(

C)

4

y = - 1.7*x - 4.4 data 1

linear

2 R= -0.81, p=0.00

0

-2

-3.4 -3.2 -3 -2.8 -2.6 -2.4 -2.2 -2 -1.8 -1.6 concurrent stem water potential(MPa)

3

2 y = - 3.3*x - 3.2

1

R= -0.80, p=0.00

data 2

linear

0

-1

-2

-3 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0

Pre-dawn stem water potential(MPa)

Figure 5. Leaf to air temperature difference versus the stem water potential during 14:30 to 15:00 of all sampling days in January

Conclusion This method of obtaining easy-to-apply and continuous wet and dry reference temperatures is still under development. From the initial results of the artificial leaf experiment, it can be expected that the wet reference temperature can be realized using wicks in the field; this will be the next step to test. However, the method of obtaining a dry reference temperature needs to be improved. By directly comparing leaf to air temperature difference with the stem water potential, it is hoped to establish that leaf temperature can be a good indicator of water stress. The variation in correlation at different times of day demands further investigation. If the correlation can be quantified under various environmental conditions and a suitable algorithm is found to obtain reasonable thermal index on unfavourable conditions such as cloudy or windy days, it will widely broaden the application of thermal imaging technique in water stress detection.

Reference Berni J, Zarco-Tejada P, Sepulcre-Canto G, Fereres E and Villalobos F (2009) Mapping canopy conductance and CWSI in olive orchards using high resolution thermal remote sensing imagery. Remote Sensing of Environment, 113(11): 2380-2388.

Gonzalez-Dugo V et al. (2012) Almond tree canopy temperature reveals intra-crown variability that is water stress-dependent. Agricultural and Forest Meteorology, 154: 156-165.

Idso S (1982) Non-water-stressed baselines- a key to measuring and interpreting plant water-stress. Agricultural Meteorology, 27(1-2): 59-70.

Idso S, Jackson R, Pinter P, Reginato R and Hatfield J (1981) Normalizing the stress-degree-day parameter for environmental variability. Agricultural Meteorology, 24(1): 45-55.

Jackson R D, Idso S B, Reginato R J and Pinter P J (1981) Canopy temperature as a crop water-stress indicator. Water Resources Research, 17(4): 1133-1138.

Jones H (1999) Use of thermography for quantitative studies of spatial and temporal variation of stomatal conductance over leaf surfaces. Plant Cell and Environment, 22(9): 1043-1055.


Jones H G (2004a). Application of thermal imaging and infrared sensing in plant physiology and ecophysiology. Advances in Botanical Research Incorporating Advances in Plant Pathology, Vol 41, 41: 107-163.

Jones H G (2004b) Irrigation scheduling: advantages and pitfalls of plant-based methods. Journal of Experimental Botany, 55(407).

Jones H G (2007) Monitoring plant and soil water status: established and novel methods revisited and their relevance to studies of drought tolerance. Journal of Experimental Botany, 58(2): 119-130.

Jones H G et al. (2002) Use of infrared thermography for monitoring stomatal closure in the field: application to grapevine. Journal of Experimental Botany, 53(378): 2249-2260. Moffett K B and Gorelick S M (2012) A method to calculate heterogeneous evapotranspiration using submeter thermal infrared imagery coupled to a stomatal resistance submodel. Water Resources Research, 48.

Testi L, Goldhamer D, Iniesta F and Salinas M (2008) Crop water stress index is a sensitive water stress indicator in pistachio trees. Irrigation Science, 26(5): 395-405.


Introducing Green Roofs into the Urban and Built Environments of Adelaide

Mostafa Razzaghmanesh* and Simon Beecham**

*PhD Student, **Professor and Head of School of Natural and Built Environments, University of South Australia

Abstract Australia is one of the most urbanized countries in the world and 85% of its inhabitants live in towns or cities. Urbanization growth increases impervious areas such as roads, roofs, parking lots, highways and pavers in the metropolitan areas. This leads to removal of remnant native vegetation cover in the urban area. It also increases runoff volume, peak flow and reduces the time of concentration. These effects bring more pressure on urban drainage systems. Green roofs, as one of the vegetated Water Sensitive Urban Design (WSUD) systems can cover the already available dense area and provide environmental, economic and social benefits. Despite such benefits, green technology is relatively new in Australia and there are research gaps and practical barriers to apply the technology widely. To address research gaps in this area and give self-confidence to authorities and organizations, two major experiments have been suggested. The first conducted in trial green roofs (as full scale experiments) built on the roof of the ANZ tower located in the City of Adelaide. The second experiment constructed at the University of South Australia (as small scale experiments). In these experiments, the water quality, quantity and thermal performances of the green roofs were investigated. The outcomes of this study will assist urban planners in developing a resilient green roof model at both the micro and macro scale for the city of Adelaide.

Key words: Water Sensitive Urban Design, Green Roofs, Adelaide, Urban Heat Island

Introduction In recent decades the hydrologic cycle of water has changed significantly due to continuous changes in Australian green spaces from forest or other intrinsic vegetation to rural or urban environments (Australian and New Zeland environment and conservation council 2000). The growth rate of urbanisation has led to changes of green spaces with large impervious areas such as roofs, parking lots, roads, highways and paving. These have led to changes of the hydrologic cycle. Figure 1, shows a conventional catchment before and after urbanization growth which increased impervious surfaces, decreased infiltration rate and then increased stormwater runoff. As a response, relatively new stormwater management strategies such as Low Impact Development (LID) (Voyde et al. 2010), Sustainable Urban Drainage Systems (SUDS) (Stovin 2010) and Water Sensitive Urban Design (WSUD) (Palla et al. 2010) have been developed in different countries. The main objectives of these strategies are to attenuate runoff peak flow and to provide pollution control. Stormwater management practices (BMP), LID, SUDS and WSUD employ two main techniques, namely potable water demand reduction and stormwater management techniques. There are some structural management tools such as sediment basins, bio-filtration swales, bio-retention basins, porous and permeable pavements and green roofs.


http://www.unisa.edu.au/nbe/

Figure 1. Illustrates the conventional urban catchment before and after urbanisation growth

However, Adelaide is the capital city of the driest state in Australia and it currently three major challenges, namely urbanisation growth, water scarcity and climate change. The consequences of these threats put more stress on the urban water cycle and increase metropolitan temperatures through urban heat island effects Error! Reference source not found.. Introducing green infrastructure through water sensitive urban design is one of the possible solutions to reduce the harmful impacts of urbanisation while providing additional amenity and water quality benefits for communities and the environment (SAGovernment 2010). Adelaide’s 30 Year Plan (2010) describes how the capital of South Australia will be one of the most water sensitive cities in the country. This plan also recommends the introduction of green roofs

Figure 3 but research is required to develop this technology to be resilient in South Australia’s harsh climate (Razzaghmanesh et al. 2012). This paper describes the results of a current research project that is investigating the water quantity and quality effects and thermal benefits of two different types of green roofs, namely intensive and extensive

Figure 2. Typical Urban Heat Island effects distribution over a city http://heatisland.lbl.gov/coolscience


http://heatisland.lbl.gov/coolscience

http://heatisland.lbl.gov/coolscience

Rain

fall

dept

h (m

m)

Figure 3. Water Sensitive Urban Design objectives and relation with Adelaide 30 -year Plan Methodology Site 1- ANZ House green roofs storm water quality

The ANZ House green roofs include 4 green roof beds. Of these 2 are intensive (AI and BI) and 2 are extensive beds (BE and AE). The area of each roof bed is 14.4 m2. Figure 4 shows the study plan and sampling points. In each water sampling event, samples from the surface of an existing asphalt roof were also collected as an experimental control.

Figure 4- ANZ House green roof layout and sampling points To estimate the possible volume of outflow from the systems, Adelaide’s rainfall was investigated for the last 10 years. Figure 5 shows the distribution of wet days (Voyde, Fassman and Simcock 2010) (rainfall with more than 2 mm in a typical year (2010). The focus of the study will be on selected rainfall events in the band of 5-20 mm depth, as shown in Figure 5.

Adelaide Rainfall Pattern (2010)- More than 2 mm/day

70 65 60 55 50 45 40 35 30 25 20 15 10

5 0 01-Jan 10-Feb 21-Mar 30-Apr 09-Jun 19-Jul 28-Aug 07-Oct 16-Nov 26-Dec

Days- Year 2010


Figure 5. Adelaide rainfall pattern of wet days in 2010 as an example year Water quality sampling method

The design of the ANZ House Figure 6 green roofs was based on a free drainage system and the designer intended to get rid of excess water from the system as soon as possible after rainfall events. Collecting water samples from the green roof beds was the main challenge in this study. Different methods were considered such as making small scale green roofs at the site, retrofitting beds and adding metal sheet around the beds to collect the water samples. However, none of these methods were feasible due to the building’s operational and maintenance requirements. The only possible way to capture enough water in the porous media was to use half round pipes buried in the soil media. Using the growing media, soil properties and considering the required volume of samples, the diameter and length of the required half round pipe was calculated as 50 mm and 700 mm, respectively. Holes were drilled at both ends of the half round pipe and lengths of hose were attached to facilitate water collection.

Figure 6. ANZ House green roofs trial The collected water samples were refrigerated at all times at the University of South Australia. Water quality tests were performed for parameters including pH, Turbidity, Electrical Conductivity (EC), TDS, Nitrate, Phosphorous, Potassium and Sodium and Chlorine. To investigate heavy metals, 2 random samples of the last data collection were sent to SA Water’s Australian Water Quality Centre (AWQC) to examine the heavy metals concentrations.

Site 2- Mawson lakes campus experiments

In this study which is associated with the ANZ House green roofs stormwater quality monitoring, the small scaled green roofs were constructed and set up at University of South Australia, Mawson lakes campus. The study site is approximately 15 km away from Adelaide CBD. In this study rainfall and runoff were measured using rain gauge Figure 7 and outflow tipping bucket Figure 8 from the green roofs downspouts. Moreover, thermal sensors were used in different beds and different depths to find out that how green roofs can mitigate the urban heat island effects Figure 9 and how much they have insulation and cooling properties for buildings.


Figure 7. Mawson lakes campus small scale green roofs

Figure 8. Outflow tipping bucket counter with water quality sampler


Figure 9. Shows the method of measuring thermal benefits of green roofs at Mawson lakes

Result and discussion Water Quality

To investigate the potential for reusing runoff from the ANZ House green roofs in the building, available local, state and national Australian water quality guidelines were reviewed. The qualities of the collected samples with regard to the alternative reuse scenarios such as potable, non-potable and urban irrigation were examined. Results showed with no doubt it is possible to reuse the green roof outflows for urban irrigation and non-potable purposes (such as toilet flushing) but this source of water is not recommended for drinking purposes.

Water Quantity

The rainfall and runoff data were collected each rainfall events and they have been accessible through the available data logger system. The results represent that the green roofs bed could mitigate the 75% of the rainfall

Figure 10 and also the y can attenuate the run off for 400 minutes. Furthermore, the water retention capacity of the green roofs bed were investigated and we concluded that green roof beds could retain the rainfall depend on the rainfall intensity, duration, antecedent dry weather period and initial moisture in the system between 44% to 100%.

∆p=1.5 mm

∆t=400 Min


Figure 10- Typical Rainfall and runoff of the green roof system of Mawson Lakes Campus Thermal Benefits

Thermal benefits of the green roofs in terms of mitigating urban heat island effects and also cooling properties have been investigating in cold and warm day’s scenarios. The results so far have shown that green roofs can be cooler in the days from 2-5 degrees depend on the media type and depth and also in the night time are warmer than surrounding area weather between 2.5 to 5.5 degrees.

Conclusion In this paper, result of the current research on introducing green roofs into the urban and built environments of Adelaide has been discussed briefly. The results confirm that green roof could act as one of the main possible options in Adelaide 30-year plan to make it for Adelaide and South Australia easier to be one of the water sensitive cities in Australia. Due to the different rages of climate in South Australia still more research are required to understand the green roofs behavior. And also, the researchers at university of South Australia are appreciating any research projects in this area and also WSUD area.

Acknowledgments The authors would like to thank Graeme Hopkins and Christine Goodwin of Fifth Creek Studio for their advice and ongoing support. We also gratefully acknowledge their client, ANZ House, for facilitating this investigation and contributing to this innovative research. We are also grateful to Tim Golding for technical advice and assistance.

References Australian and New Zeland environment and conservation council (2000) "Australian guildelines for urban stormwater management ".

Palla A, Gnecco I and Lanza L (2010) "Hydrologic restoration in urban Environmental Using Green Roofs." Water 2: 140-154.

Razzaghmanesh M, Beecham S and Kazemi F (2012) The role of greeen roofs in Water Sensitive Urban Design in South Australia. 7th international conference on Water Sensitive Urban Design, Melbourne, Australia, Center for Water Sensitive Cities, Monash University.

SA Government (2010) The 30- Year Plan for Greater Adelaide. Department of Planning and Local Government. South Australian Planning Strategy.

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