Sclerophyllous Forests

Jarrah Forests

Sclerophyllous Forests The Jarrah forest is a diverse ecosystem which

contains many unique species of plants and animals that are able to cope with a relatively dry climate. A major feature of the vegetation is that it is sclerophyllous. That is, plants possess hard, leathery leaves that enable them to reduce transpiration and therefore resist the drought conditions of summer.

The relationships of linkages that exist between the biotic and abiotic components enable the jarrah forest to function as a distinctive natural environment.

Wet Sclerophyllous Wet schlerophyllous

include Karri, Mountain Ash and Blue Gum trees.

Dry Sclerophyllous Dry sclerophyllous

trees include jarrah, marri, South Australian red gum, stringy bark, spotted gum and box.

Sclerophyllous Forest Region

Location

Climatic Data Characterised by: Cool, wet winters and hot, dry summers. Rainfall between 700-1000mm Winter maximum rainfall (80%), and

prolonged periods of low humidity and high evaporation during summer.

Rainfall decreases rapidly away from the coastal zones and any forested areas give way to woodlands and scrub.

Vegetation In Australia, the Mediterranean vegetation

types include the Mallee scrub as well as dry and wet eucalyptus sclerophyllous forests.

Variety of drought resistant or xerophytic adaptations.

Prone to frequent fires, especially during summer when the temperatures are high and the winds are strong.

VEGETATION JARRAH Slow growing evergreen hard wood

with a long straight trunk and vertically grooved bark. Grows to over 50 metres. Requires between 700 and 1100 mm of rain. Wood is a red-brown colour. Grows in association with Marri

Upper Storey- formed by the tops of the Jarrah. Forms a discontinuous canopy allowing plenty of sunlight through to lower levels

Middle Storey- formed by Marri and Blackbutt. Average 20m in height

Lower Storey- very complex layer of shrubs wildflowers and goundcovers

eg. Kangaroo Paw

KARRI/TINGLE Occupies the same position in

the Wet Sclerophyllous as the Jarrah does in the Dry Sclerophyllous

Similar general characteristics as the Jarrah forest

TASK1. Diagram the structure of the Jarrah

forest pg 36 World Biomes2. Complete worksheet of

adaptations of sclerophyllous vegetations

ADAPTATIONS LEAF STRUCTURE LIGNOTUBERS TRUNK FACE DOWN LEAVES OILY DEEP TAPROOTS EPICORMIC BUDS THICK BARK

REASONS FOR ADAPTATIONS:1. FREQUENT SUMMER

FIRES2. SUMMER DROUGHT3. EXTREME SUMMER HEAT4. HIGH EVAPORATION

RATES IN SUMMER

Vegetation Adaptations Mediterranean forests have developed in association with

the periodic fires that are generated by lightening strikes during the dry summers.

Leaf litter and leaves on most plants are high in oil content and are volatile. Fires spread rapidly once started.

Trees have features such as lingotubers and epicormic shoots, which illustrate their adaptation to fire.

Epiormic shoots are special branches that grow from branches, trunks and roots after fire to allow photosynthesis to be restarted.

Lingotubers are large root crowns that produce shoots after fire.

Many plants also have seed cones that open after a fire passes, allowing seeds to be deposited in the ash bed.

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Layers of a Jarrah Forest Like rainforests, the wet and dry

schlerophyllous forests have distinctive layers of strata. Tall trees such as jarrah, karri and marri form the canopy.

The middle storey includes banksia, acacia, melaleuca and casurina.

The understorey includes grasstrees, cycads (zamia palms), acacia, melaleuca and hakea shrubs and a variety of wildflowers.

Jarrah Forest

Upper Storey

Middle Storey

Understorey

Location of wet/dry Sclerophyllous Sclerophyllous forests and woodlands are located

almost entirely along the western coastal margins of continents.

The Jarrah forest is located in the South West of Western Australia.

The forest extends from just north of Perth southwards to Manjimup, and from there south eastwards to Albany.

The forest lies on the Darling Scarp/Plateau in areas receiving over 700mm of rainfall.

Animals of a Jarrah Forest The sclerophyllous forests of Australia contain

animals such as the grey kangaroo, as well as possums, bandicoots, numbats, pademelons and wallabies. Bird life includes parrots, honeyeaters, owls and hawks.

Significant communities of arboreal and ground dwelling animals can be found in the sclerophyllous forest.

In Australia a significant number of tree dwellers can be seen in forests and woodlands.

ANIMAL LIFE IN THE JARRAH FOREST ANIMALS Native species Numbat, echidna,

kangaroo, emu, chuditch, possum, numerous bird species

Introduced species Rabbit, fox, cat, dog, rat,

mouse, sheep, goats, ant species

Animal adaptations to the environment

Nocturnality Control their own breeding Short gestation to take

advantage of a good season

Low water needs or get their water from their food

Introduction of foreign animal species This has had a significant impact on the jarrah

forest ecosystem, creating an unbalances ecosystem and producing endangered species.

European settlers introduced large predators such as foxes, feral cats and pigs, and birds of prey such as the kookaburra.

These animals have been able to multiply greatly in an ecosystem which originally had no large predators.

This has reduced the populations of many small native mammals such as the numbat.

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Numbat (Myrmecobius fasciatus),

Long-nosed Potoroo

Topography – Darling scarp/plateau The Jarrah Forest sits on the western edge

of the Darling Plateau. The plateau surface is approx. 400m high and is gently undulating with broad shallow valleys and gentle rises.

The western edge of the plateau consists of the north-south aligned escarpment, the Darling Scarp (Darling Ranges). This steep slope separated the plateau from the Swan Coastal Plain.

Topography of the South west DARLING SCARP Technically is the western

edge of the Darling Plateau. Is an escarpment with a steep western facing slope rising to a total of 580 metres at Mt Cooke

Dissected by westward flowing streams like the Avon, Serpentine, Murray and Canning

Known for Granite outcrops called Tors

DARLING PLATEAU A gently sloped plateau

east of the Darling Scarp decreasing in height from 400 m to 100m at Merredin

Flat land largely clearly for wheat sheep agriculture

95% of Wandoo forest has been cut down in the process

Irregular intermittent drainage of dry streams and salt lakes

TOPOGRAPHY cont. Swan Coastal plain Coastal Lowlands consisting of sand plains dissected

by rivers flowing from the Darling Scarp. Some rivers have formed large fertile valleys covered by rich alluvial soils and wetlands. Best example is the Swan Valley which is a famous wine region and fruit and vegetable production.

WA’s large growing coastal cities are located in this area eg. Perth, Joondalup, Mandurah, Bunbury and Busselton.

Urban development and agricultural landuses has led to the loss of 90% of the Tuart forest.

TASK Draw a sketch map identifying the location of the Jarrah forest

Drainage - Darling Scarp/Plateau The drainage of the area consists of a

series of westwards flowing streams. Examples include the Helena, Canning,

Serpentine, Murray and Blackwood Rivers. These rivers have severely dissected the

face of the scarp, carving out deep valleys, the sides of which contain many rock outcrops.

Drainage onBibbulmun map

Soils – Laterite soils In Australia, wet and dry sclerophyllous forests

are located mainly on the red clay lateritic and terra rossa soils that have weathered from granite rock. They often contain nodules of gravel associated with aluminium and iron concentration and may have a deep layer of white kaolin clay.

Generally slow breakdown of humus results in a build-up of dry leaves and a wood with the nutrients being released only after fire. The absence of phosphate in Australian soils is a dominant characteristic of nutrient cycles within the forests.

The laterites have been formed by the deep weathering of the granite rock of the plateau.

SOILS OF THE SOUTH WEST Jarrah will grow in a variety of

soils including sand but it prefers the soil found in the Darling Scarp the Laterite gravel.

Laterites are the deep reddish infertile gravels found in the Scarp. They are a relic from a wetter time when weathering was greater millions of years ago. The granite bedrock of the Scarp weathered into a deep layer of gravel on top of a lateritic caprock layer. Underneath this is a layer of Bauxite which contains Alumina

We use this gravel on our gardens around our trees

TASKDiagram the Laterite soil profile

found on pg. 38 World Biomes

SHORT ANSWER QUESTIONDescribe the topography, climate,

vegetation and soil characteristics of the Jarrah forest.

(In an exam this would be worth 4 marks)

Profile of the Lateritic Soils of the Jarrah Forest.Litter layer(slowly decomposing)

2-5cm Topsoil 50cm Gravelly sand

A Laterite caprock (rich in Bauxite)

50cm

B Bauxite Layer (weathered gravel stone.)

5-10m

C Kaolin (White Clay)

Deeply weathered parent rock Granite Rock

Relationships in the Jarrah Forest

Climate – Vegetation – AnimalClimate – Soil – Vegetation

Soil – Vegetation – TopographyClimate – Landforms – Soil

Climate – Vegetation - Animal Climate determines boundaries by vegetation type. Distribution of vegetation to the north and east is limited by

rainfall. Vegetation structure is a response to the climate.

Open nature, with three distinct storeys Canopy of the tall trees has created a shadier micro-climate in

the lower layers (understorey) Features of plants a result to climate

Tall Jarrah tree result of high water availability Sclerophyllous plants – they possess tough, slender leathery

leaves to reduce moisture loss. Xeromorphic – able to withstand long dry periods Strong ‘sinker’ root system – penetrate cracks and gaps in the

soil’s hard caprock in order to locate water. Adapted to survive fires (thick bark, regeneration, seeds pods,

buds, swollen root (lingo-tuber) which stores food.)

Animals adapted to the climatic conditions. Tammar wallabies are well adapted to surviving on dry foods

and a low water intake. Reptiles use the summer heat to regulate body temperature. Frogs can burrow into soil to stay cool. Dunnart shelters by day in logs and come out at night to feed

on insects, spiders and lizards. Animals and their habitats also rely on fire.

Tammar wallaby relies on thickets of the heart-leaf plant for shelter. This plant relies on fire to keep it young and bushy and therefore creates shelter for the wallaby.

Grey kangaroo likes to feed on lush new grasses that spring up after an area has been subject to fire.

The mardo is commonly found in areas that have been unburned for a long period of time as it lives on small invertebrates that dwell in the leaf litter on the forest floor.

Climate – Soil – Vegetation Soils are a product of the granite rocks of the Darling

Plateau, and of the interaction between climate and vegetation.

Climate is particularly important in producing laterites. They were formed in the past when the climate was hotter

and wetter than it is now. Under these tropical conditions the granite rock quickly

weathered to provide the mineral content of the soils The climate was also responsible for the concentrations of

iron and aluminium being left near the surface to form a hard layer, the lateritic caprock.

This has weathered to form the sand and gravel soils that are characteristic of the jarrah forest.

The tropical climate was responsible for the lack of nutrients in the soils as they were washed out to the deeper levels by the high rainfall.

This heavy leaching of nutrients has left behind the concentrations of iron and aluminium that form the caprock layer.

There has been no renewal of nutrients in recent times because the land surface has been stable for so long. – no uplifting of land which might have otherwise have provides new minerals as a result of the weathering of new surface rock.

The topsoils layer of the laterite is relatively shallow because of the general lack of organic material.

The leaves of the litter are hard and dry, and therefore decompose very slowly under the dryer conditions of today’s climate.

Vegetation stabilises soils, root systems prevent mass movement.

Soil – Vegetation - Topography Strong relationship between soil and vegetation. Because infertile soil, only specialised plants are

able to grow on the harsh gravelly soils. Eg Jarrah, Marri, Karri (strong sinker roots- to reach the water table. Important especially in summer drought)

Sclerophyllous leaves response to the lack of nutrients in the lateritic soils.

Decomposition of leaves occurs slowly in the jarrah forest, so fires are largely responsible for releasing the nutrients locked up in the litter layer and making them available for plants. Ash is a natural fertiliser for plants.

Vegetation controls water movement in the soil. Some rainfall intercepted by the vegetation canopy,

stems and branches and is either held and subsequently evaporated or it drips from the canopy.

Remainder falls through the canopy to the soil surface where most of it infiltrates to become part of the soil water.

The soil water is either stored, absorbed by roots and transpired back into the atmosphere, evaporated at the soil surface or is used to recharge groundwater.

It is returned eventually, via streams and rivers, the the ocean.

Topography and soils also have an impact on the vegetation. Jarrah is abundant on the top ridges and upper slopes of

valleys where the thickest laterite occurs. Jarrah is confined to areas with deeper soils. Marri tends to dominate the moister valley slopes and

floors and is common near the bottom of valleys and around granite outcrops, which act as water catchment areas.

Blackbutt, bullich and flooded gum are found on the valley floors where fertile soil has built up from stream deposition.

Plants of the understorey vary according to variations in soil moisture requirements.

Sheoaks prefer poorer sandier soils that are well drained whereas banksias are found on more gravelly soil.

Climate – Landforms - Soil Temperatures and rainfall have both been responsible for

affecting landforms as they have influenced rates of weathering and erosion.

The granite rocks of which the plateau is made are continually being weathered and eroded by rivers, especially during and after the wetter months. Swollen rivers during winter have carved the narrow and steep river valleys in the western part of the ecosystem.

The shape of the land surface does influence climate. The sharp change in altitude from the low coastal plain to the top of the plateau is responsible for increasing the rainfall immediately east of the scarp.

Onshore moisture-laden westerly winds in winter are forced to rise, producing orographic rainfall. Also temperatures are lower at higher altitudes.

Vegetation – Animal relationships As in all ecosystems plants and animals of the

jarrah forest are related in a number of ways, primarily through food chains.

The vegetation is the ultimate source of nutrients for all food chains that support life.

It also provides habitats for animals. Trees provide homes for birds, insects and

possums. Provide various nesting sites, and their crowns

provide shelter and camoflarge.

Animals affect vegetation in a number of ways Spread seeds, pollinate plants and help control pests.

Animals can also provide homes for other animals. Termites hollow out tree trunks and branches creating shelters

for other animals such as parrots and possums. Some introduced species disrupt the natural food chain

systems of the forest. Kookaburra lacks natural predators to keep numbers down. Foxes are not fussy and eat many animals. It too has no

natural predator in the ecosystem. The type, availability and seasonal distribution of food also

play an important part in the relationship between plants and animals. Many primary, secondary and tertiary consumers have varied

diets and their ability to switch food as supplies change with the seasons is important.

Food Chains in Jarrah Forests

Solar Energy Energy Losses

Grass -> Wallaby -> Dugite -> Eagle -> Bacteria

Producer Primary Secondary Tertiary Decomposer Consumer Consumer Consumer

Ecological Pyramid Feeding Levels Eagle 5 Goanna 4

Numbat 3

Termites 2

Producers (tree trunks, logs) 1

Producers, Consumers and DecomposersPrimary Producers

Primary Consumers

Secondary Consumers

Decomposers

Jarrah TreeMarri TreeBanksiaWattleZamiaBracken FernPoison PeaAnnual Grasses

ParrotPossumWallabyWaylieKangarooCaterpillar

NumbatBirdEchidnaDugiteFrogSkinkGoanna

EarthwormFungusBacteriaMillipedeMiteSpringtailSlaterTermite

Human Impact – usage of the Jarrah Forests.

Uses of the Jarrah Forest The jarrah forest is used today for

agriculture, forestry, mining, water catchment, urban and transport uses and as a recreational resource (for activities such as hiking, rock climbing, picnicking, sightseeing, canoeing, fishing and camping).

Most if the jarrah forest ecosystem is reserved as state forest.

Uses of the Jarrah Forest.

Mining

Urban/transport

Agriculture

Timber production

Water Catchment

National Parks

JarrahForests

What changes have occurred as a result of human activity? Altered the vegetation of the ecosystem Introduced weeds Altered vegetation layers Clearing increasing salinity problems Greater through-flow of water in soil and over soil

as a result of clearing Logging and mining (clearing) reduces

transpiration and effects natural water cycle. Dieback disease. Fungal soil-borne. Attacks at

roots and causes jarrah and banksia trees to die. Spreads most rapidly when soil is moist and warm.

Introduction of foreign animal species.

WHY KEEP THEM? Values of the old growth forest include: Ecological and scientific value: WA forests are known the world

over for the unique species which live in their ecosystems. Many of the species are only found in Western Australia (endemic species). For example, karri, jarrah and marri trees don't naturally grow anywhere else in the world. There are about 50 species of birds and mammals, such as the forest red-tailed black cockatoo and the brush-tailed possum, which depend on hollows in these big old growth trees to live and nest in. There are also unknown numbers of insects and fungi species yet to be named or even discovered by scientists. When the forest undergoes a massive disturbance like logging and burning we may be losing species forever that we didn't even know we had.

Economic value: Old growth forests are important for industries other than logging, such as tourism, wildflower picking, fine wood-craft and beekeeping. These industries are more ecologically sustainable than logging or mining in old growth forest because they don't disturb the natural life cycle of the ecosystems. We need more old growth forest put into national parks and nature reserves for the increasing numbers of people wanting to appreciate our unique natural heritage.

BIO DIVERSITY BiodiversityOld growth forests have a high level of biodiversity,

which means there are lots of different species of plants and animals found there. The South West Botanical Province (from Geraldton to Albany) is one of the world's richest areas of flowering plants, with approximately 9000 species of which over 70 % are endemic (CALM, A Nature Conservation Strategy for Western Australia, draft for public comment, 1992). Scientists are still discovering previously unknown species. For example, in a study of 20 marri trees, an average of 443 species of insect were discovered living on each tree. Many of these had never been recorded by scientists before. (H.F. Recher, J. D. Majer & S. Garnesh - 'Eucalypts, arthropods and birds; on the relation between foliar nutrients and species richness.' Published in Forest Ecology and Management, 85 (1996) p177-195.)Old growth forests are made up of trees of many different ages, sizes and shapes, and their understorey. This is known as structural diversity. For example, big old trees, living and dead, standing or fallen, with hollows of all different shapes and sizes, provide homes (habitat) for a wide variety of species, from cockatoos and possums to mosses and fungi. Regrowth forests are made up of trees that are nearly all the same age, and do not have the structural diversity or variety of habitat found in old growth forest.

Threats to biodiversity

Habitat clearing (e.g. clearing for farming or vineyards)

Habitat modification (e.g. prescribed burning, clearfelling)

Pollution (e.g. chemical run-off from agriculture) Introduced flora and fauna (e.g. watsonia, bridal

creeper, blackberry, foxes, cats and wild pigs) Diseases (e.g. dieback in the jarrah forest) Global climate change (e.g. greenhouse effect

and ozone depletion) Size and distribution of the human population and

the level of consumption of natural resources

What does the Jarrah Forest do for us? Ecological services of old growth forest Old growth forest provides many important services which

ensure the ongoing health and stability of the environment. Humans are part of the environment and our well-being depends on having a healthy environment. These services are:

Maintenance of hydrological (water) cycles Climate regulation Soil production and fertility and protection from erosion Nutrient storage and cycling Pollutant breakdown and absorption Potential source for genetic material for new drugs and food

crops  

WHY KEEP THEM? Values of the old growth forest include: Ecological and scientific value: WA forests are known the world

over for the unique species which live in their ecosystems. Many of the species are only found in Western Australia (endemic species). For example, karri, jarrah and marri trees don't naturally grow anywhere else in the world. There are about 50 species of birds and mammals, such as the forest red-tailed black cockatoo and the brush-tailed possum, which depend on hollows in these big old growth trees to live and nest in. There are also unknown numbers of insects and fungi species yet to be named or even discovered by scientists. When the forest undergoes a massive disturbance like logging and burning we may be losing species forever that we didn't even know we had.

Economic value: Old growth forests are important for industries other than logging, such as tourism, wildflower picking, fine wood-craft and beekeeping. These industries are more ecologically sustainable than logging or mining in old growth forest because they don't disturb the natural life cycle of the ecosystems. We need more old growth forest put into national parks and nature reserves for the increasing numbers of people wanting to appreciate our unique natural heritage.

WHY KEEP THEM? 2 Aesthetic value: The old growth forest is amazing and

beautiful. Logging, clearing and mining are changing that original landscape forever. Small isolated pockets of old growth forest and road side reserves which we all see from the car on our way down south do not compare with an area that you can walk through for hours. Cultural and spiritual values: Old growth forests are part of the heritage and living environment of all Australians. As recent community protest over the continued logging of old growth forests has shown these forests have important cultural and spiritual significance for many different people. Aboriginal people have a deep connection with the land of the South West as it is the place where the Nyoongar culture and spiritual understanding come from. Their knowledge base and cultural identity are closely intertwined with the land and its life forms. "We are of this land, and this land is of us".

URBAN DEVELOPMENT Major towns in the

Jarrah forest: Collie, Bridgetown, Pemberton, Manjimup

LOGGING FOR WOODCHIPS Marri is logged after

the Jarrah has been logged for paper production. This is the

Woodchip pile waiting to be exported in Bunbury

BAUXITE MINING Alcoa mines the Jarrah forest

for Bauxite the raw material behind Aluminium

TASK Describe the process of

bauxite mining in the Jarrah Forest and diagram the impact of the mining on the forest

Figure 3.12 Page 48

SALINITY Salinity becomes a problem after the forest is cleared. The

deep rooted vegetation is no longer there to draw out water from the water table. The water rises through the soil dissolving salt as it does, the salty water kills the roots of plants, killing the plant. If this water reachs the surface, it evaporates leaving the salt behind on the surface as a salt scald

Copy Figure 3.10 into your notebook Short Answer Task Describe the uses of the Jarrah forest and the impact of two

of these uses on the Jarrah forest(Worth 6 -8 marks in an exam)

DIEBACK Technical name Phytophora It is an import from Europe

and Asia. It is a fungus that attacks the roots of plants in spring.

It moves in the soil after rainfall

It kills plants by stopping its roots from absorbing nutrients and the plant rots from the roots up

The only cure is quarantining off the uneffected from the effected forest

Dieback Disease Has had such an impact on the forest that it is now

considered to be a major factor in jarrah forest ecology and management.

Dieback fungus grown in the roots of certain susceptible plants like jarrah and banksia, causing them to rot.

The plant dies because it is starved of nutrients. The fungus spreads most rapidly during spring and autumn

when soil conditions are moist and warm. Animals and humans can spread the disease. Infected soil can be transported during logging and mining

operations, road making and activities that might disturb drainage patterns.

Dieback disease has a great impact on the environment, animal habitats and on human economic activities.

Dieback The ‘graveyard look of dead trees in the forest creates an

unattractive, depressing environment. Dieback affects incomes from economic activities such as

logging and beekeeping enterprises. It also has a possible effect on salinity by reducing the

number of plants available to take up water, and therefore increasing water supply.

As well, it reduces the extent of animal’s habitats. As a result of the seriousness of the problem a variety of

hygiene and quarantine procedures have been developed in an attempt to minimise the transmission of disease.

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CLEAR FELLING The Process of Logging 1.An area of forest called a Block is selected by CALM and given to the

logging company 2.Seed is collected in the Block for regeneration later 3.Good Jarrah logs are harvested and Marri logs are woodchipped 4.Scrap timber and ground plants are burnt 5.The Block is re-seeded

REGENERATION After mining Alcoa replaces

the top soil and re plants the forest. The replanted forest is often much denser than the old growth forest it replaces

South west of Manjimup (Jarrah marri)

Dombakup State Forest - near Northcliffe. Now replanted as a karri plantation

Easter State Forest - south of Nannup. (Jarrah, blackbutt, marri)

Karri Forest

Karri Forest South West W.A.

Eucalyptus Diversicolor

Eucalyptus Diversicolor Location

Acacia

Eucalyptus

Eucalyptus KondininensisLocation

Eucalyptus Staeri

Eucalyptus StaeriLocation

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Bibliography Planet Earth – Environment and People. By

Norman J Snell 2005 World Biomes – Diane Guy – Geographical

Association of Western Australia. 1997 Our Wonderful World – Second Edition.

Colin Sale. 1994 Burgo and Bec