vanwassenaer_conservation arboriculture
TRANSCRIPT
URBAN FOREST INNOVATIONS INC.
Philip van Wassenaer, B.Sc., MFC 1248 Minnewaska Trail Mississauga, Ontario web: www.urbanforestinnovations.com email: [email protected]
CONSERVATION ARBORICULTURE: MAINTAINING OLD TREES IN THE HUMAN LANDSCAPE
Society of Municipal Arborists International Urban Forestry Conference September 25-28, 2011 Milwaukee, WI
Presentation Outline
• Heritage Trees
• ‘Working Trees’ – A History of Tree Management
• Urban Forestry and the Benefits of Trees
• Conservation Arboriculture
• Tree Risk Assessment: Theory and Methods
• Management Options for Retaining Old Trees
Heritage Trees – A Definition
• In 2001, Dr. Paul Aird, Professor Emeritus, Faculty of Forestry, University of Toronto was asked to create a definition of heritage trees.
Heritage Trees
A Heritage Tree or Heritage Plant
• An outstanding specimen due to size, form, shape, age, colour, rarity, genetic constitution, or other distinctive features
• A distinctive community landmark
• A specimen associated with a historic person, place, event or period
• A representative of a crop grown by ancestors and their successors that is at risk of disappearing from cultivation
• A specimen recognized by members of a community as deserving heritage recognition
• Dr. Konijnendijk – defining a sense of place.
Heritage Trees
H
eritage Trees
Edigna, a “Hermit nun” and the daughter of the King of France, is said to have lived in the hollow of this tree from 1075 - 1109
Ficus Planted by Pres. Roosevelt, Early 1900s – San Diego, CA
Courtesy: Darin Hinesly
Heritage Trees
Theodore Roosevelt:
“A people without children would face a hopeless future; a country without trees is almost as hopeless…”
Heritage Trees
Working Coppice ‘W
orkin
g Trees’
Ready for Coppice
Coppice Harvested
Coppice Regeneration
Coppice with Standards
Urban Forest Benefits U
rban
Forestry
The urban forest provides a wide range of services such as:
• Improved air quality
• Micro-climate effects (e.g. shading)
• Property value & aesthetics
• Storm-water attenuation
• Energy conservation
• Noise reduction
• Wildlife habitat
• Physical & psychological wellbeing
• etc.
What is Conservation Arboriculture? C
on
servation
Arb
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Conservation arboriculture is an ecosystem approach to understanding and working with trees.
• A multidisciplinary science informing practical management of trees.
• Trees are habitat, homes for inter-dependent species.
• Trees have co-evolved with other organisms.
• To optimise their health trees require functioning, balanced natural ecosystems, above and below ground.
Introduction to Veteran Trees: A UK/European Perspective C
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• In 1993, the Ancient Tree Forum was formed in the UK to discuss management of ancient trees.
• Led to the formation of the Veteran Tree Initiative (1996), to develop a standard for identification, assessment and management of veteran trees in Europe.
Old Trees – History and Habitat C
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Old trees are important habitat for saproxylic beetles and other organisms.
living on dead wood
Jonsell (2004) found that old oaks and lindens (up to 300+ years) in Swedish parks have comparable ‘red-listed’ beetle diversity as old remnant natural areas.
By conserving old trees in cultural landscapes, we can protect history and habitat at the same time.
Redwood Rainforest
Coast Redwoods
• 115 trees/ha • 12 trees have 95% of the biodiversity • These are the old trees with broken tops, etc.
Co
nservatio
n A
rbo
ricultu
re
How Trees Fail C
OM
PA
NY P
RO
FILE
Fracture Stem / Limbs
Uprooting Stem Base / Root failure
Often result of internal damage,
which is often difficult to estimate from
the outside.
Typically caused by root decay or damage,
or failure of the root/soil interface.
Tree Risk A
ssessm
ent
Trees Fail – but they don’t always fall down!
A veteran oak between Milton and Burlington, ON
Tree Risk A
ssessm
ent
Tree Risk Assessment - Methods Tree R
isk Asse
ssmen
t
• Visual Tree Assessments
• Hammer Test
• Drilling - fine bits or increment core
• Drilling - Penetrometer
• Sonic Tomography
• Elasto-Inclinomethod, SIA
• Others (e.g. Tree Radar)
Traditional Methods
Advanced Methods
Drilling and Residual Walls Tree R
isk Asse
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Decay
• Drilling only selectively detects the residual wall
• Information obtained is insufficient to describe the state of the tree...
• ... or the number of holes has to be so high that the damage is greater than the information obtained
Sonic Tomography Tree R
isk Asse
ssmen
t
Sonic travel paths
Receiver
Receiver
Receiver
Receiver
Impact – Start Signal
Damaged wood (decay, cavity..)
Receiver
Receiver
Receiver
Statics Integrated Method – Pulling Test Tree R
isk Asse
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• Winch creates the wind simulation force • Different positions of instruments
Retrenchment Pruning Terminology C
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• Stabilisation
• Promotion of internal growth
• Redeployment of resources
• Epicormic stimulation
• Rejuvenation/reiteration
• Management of meristem tissue
• Phased according to form and vitality
Threats and Challenges
• Abiotic and biotic influences are threatening all of our trees, and heritage trees may be especially vulnerable
• The challenge is for us to find effective ways to offer real protection to trees identified as heritage features
Co
nclu
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Conservation Arboriculture Do’s and Don’ts
• Intervene as a last resort • Manage by restoring naturally functioning systems • Don’t intervene without knowing about the soil-rooting ecosystem • Crown management should mimic natural aging process and species survival mechanisms • Manage to retain maximum biodiversity
Co
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Conservation Arboriculture Guiding Principles
From the National Tree Safety Group (UK) 2010 draft guidance document:
1. Trees provide a wide range of benefits to society
2. Trees are living organisms which naturally lose branches or fall
3. The risk to human safety from trees is very low
4. Tree owners have a duty of care for their trees
5. Approach to tree management must be balanced and proportionate.
Co
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QUESTIONS? COMMENTS?
Philip van Wassenaer, B.Sc., MFC ISA Certified Arborist ON-0361A ASCA Member
1248 Minnewaska Trail Mississauga, Ontario, Canada L5G 3S5 (905) 274-1022
e-mail: [email protected] or [email protected] http://www.urbanforestinnovations.com