Sclerophyllous Forests
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Sclerophyll ous 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
TASK 1. Diagram the structure of the Jarrah forest pg 36 World Biomes 2. 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: 2. FREQUENT SUMMER FIRES 3. SUMMER DROUGHT 4. EXTREME SUMMER HEAT 5. 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. Back
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. Back
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 on Bibbulmun 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
TASK Diagram the Laterite soil profile found on pg. 38 World Biomes
SHORT ANSWER QUESTION Describe 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 50cm
A
Topsoil Gravelly sand
Laterite caprock (rich in Bauxite)
50cm
B
Bauxite Layer (weathered gravel stone.)
5-10m
C Deeply weathered parent rock
Kaolin (White Clay) Granite Rock
Relationships in the Jarrah Forest Climate
– Vegetation – Animal Climate – Soil – Vegetation Soil – Vegetation – Topography Climate – 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
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.
Spread seeds, pollinate plants and help control pests.
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 Consumer Consumer
Tertiary Decomposer Consumer
Ecological Pyramid Eagle Goanna
Feeding Levels 5 4
Numbat
3
Termites
2
Producers (tree trunks, logs)
1
Producers, Consumers and Decomposers Primary Producers
Primary Consumers
Secondary Consumers
Decomposers
Jarrah Tree Marri Tree Banksia Wattle Zamia Bracken Fern Poison Pea Annual Grasses
Parrot Possum Wallaby Waylie Kangaroo Caterpillar
Numbat Bird Echidna Dugite Frog Skink Goanna
Earthworm Fungus Bacteria Millipede Mite Springtail Slater Termite
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. National Parks Water Catchment
Mining Jarrah Forests
Timber production
Urban/ transport Agriculture
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 woodcraft 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 woodcraft 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. Back
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
Eucalypt us Diversico lor Location
Acacia
Eucalyptus
Eucalypt us Kondinin ensis Location
Eucalyptus Staeri
Eucalypt us Staeri Location
Back
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
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
TASK 1. Diagram the structure of the Jarrah forest pg 36 World Biomes 2. 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: 2. FREQUENT SUMMER FIRES 3. SUMMER DROUGHT 4. EXTREME SUMMER HEAT 5. 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. Back
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. Back
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 on Bibbulmun 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
TASK Diagram the Laterite soil profile found on pg. 38 World Biomes
SHORT ANSWER QUESTION Describe 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 50cm
A
Topsoil Gravelly sand
Laterite caprock (rich in Bauxite)
50cm
B
Bauxite Layer (weathered gravel stone.)
5-10m
C Deeply weathered parent rock
Kaolin (White Clay) Granite Rock
Relationships in the Jarrah Forest Climate
– Vegetation – Animal Climate – Soil – Vegetation Soil – Vegetation – Topography Climate – 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
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.
Spread seeds, pollinate plants and help control pests.
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 Consumer Consumer
Tertiary Decomposer Consumer
Ecological Pyramid Eagle Goanna
Feeding Levels 5 4
Numbat
3
Termites
2
Producers (tree trunks, logs)
1
Producers, Consumers and Decomposers Primary Producers
Primary Consumers
Secondary Consumers
Decomposers
Jarrah Tree Marri Tree Banksia Wattle Zamia Bracken Fern Poison Pea Annual Grasses
Parrot Possum Wallaby Waylie Kangaroo Caterpillar
Numbat Bird Echidna Dugite Frog Skink Goanna
Earthworm Fungus Bacteria Millipede Mite Springtail Slater Termite
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. National Parks Water Catchment
Mining Jarrah Forests
Timber production
Urban/ transport Agriculture
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 woodcraft 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 woodcraft 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. Back
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
Eucalypt us Diversico lor Location
Acacia
Eucalyptus
Eucalypt us Kondinin ensis Location
Eucalyptus Staeri
Eucalypt us Staeri Location
Back
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
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