Ecosystems - egcma.com.au Biodiversity.pdf · nutrients needed to support life such as phosphorus...

An ecosystem is a term used to describe a community of plants and animals, and their interactions with thenon-living aspects of the environment such as the soil, water and air. It is the study of the transfer of energyand matter between the living and the non-living world at a given location. This could include a garden,wetland, river, forest or coast.

O U R B I O D I V E R S I T Y

E c o s y s t e m sE c o s y s t e m s

What’s in an ecosystem?

An ecosystem has two main components, the bioticor living component and the abiotic or non-livingcomponent.

Biosphere Consists of all organisms in the five kingdoms:

• Monera – microscopic single celled prokaryoticorganisms such as bacterias and thecyanobacterias, e.g. blue green algae

• Protistata – single celled eukaryotic organismswhich include amoebas, diatoms, protozoa andslime moulds

• Fungi – (mostly) multicelled eukaryotic organismsincluding mushrooms, moulds and yeasts

• Plantae – (mostly) many celled eukaryoticorganisms including most algaes, moss, ferns,conifers and flowering plants

• Anamalia – multicelled eukaryotic organismsincluding invertebrates – animals withoutbackbones and vertebrates animals withbackbones

Hydrosphere Consists of all the water on earth including:

• Lakes• Rivers• Oceans• Ice-caps• Groundwater• Water vapour

Atmosphere Consists of the layer of air around the planetincluding:

• The troposphere that contains most of the oxygen

• The stratosphere which houses the ozone layer tofilter harmful solar radiation

Lithosphere Includes the Earth’s crust and upper mantel.

• It consists of rocks and minerals, soil andnutrients needed to support life such asphosphorus

Why are there different ecosystems?

The physical characteristics of an ecosystemdetermine the species that are able to live there. For example, wet forests support plants that such as ferns that require moisture to complete their lifecycles. These plants are unable to exist in hot dryclimates.

Factors such as rainfall, temperature, light andsalinity also impact upon the distribution of plantsand ecosystem types.

Atmosphere

Hydrosphere

Lithosphere

BiosphereECOSYSTEM

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What does an ecosystem do?

The function of an ecosystem is to harness the sunsenergy and transfer that energy between all livingthings. Ecosystems also cycle matter such as thenutrients in a plants leaves between their biotic andabiotic parts.

The processes that drive these cycles are interactionsbetween the ecosystem components. Evaporation isan interaction between the hydrosphere and theatmosphere, taking heat out of the ecosystem. Theprocess of photosynthesis is a interaction betweenthe atmosphere, the hydrosphere and the biosphere.

Photosynthesis equation

The flow of energy in ecosystems

Organisms Organisms have a functional role in the transfer ofthis energy based on where they are in the foodchain. Producers or autotrophs can manufacturesimple sugars via photosynthesis and the help ofsunlight. This task is undertaken primarily by plantson land. In aquatic ecosystems, producers arephytoplanktons such as cyanobacteria andmicroscopic algae.

Once harnessed by plants, the energy may betransferred to animals through consumption.Animals that eat plants are known as herbivores.Animals that eat animals are termed carnivores.Some animals eat both plants and animals and arecalled omnivores.

The final stage of the cycle is to return the matterfrom dead plants and animals and their wastes backinto useful matter for the ecosystem.

The decomposers are organisms that physically andchemically break down complex organic moleculesinto inorganic compounds that can then be utilisedby the producers again.

Food chains and food websFood chains rarely have more than four feedinglevels. Simple food chains can be identified inecosystems by looking at the diet of an organism, i.e. Caddisfly larvae eat duckweed. But in realitythese relationships are more complex, i.e. a Caddisfly larvae eats not only duck weed, but grass and a variety of plant matter.

Biomass and ecological pyramidsBiomass refers to the weight of all organic matter inan ecosystem. Each feeding level has a differentamount of biomass. For example, in a wetlandecosystem, there may be thousands of free floatingduck weed (producer), a few hundred Caddisflylarvae (primary consumers) and only a handful ofGalaxias (secondary consumers)

As energy in the form of food is transferred betweeneach trophic level, a percentage is lost in the form ofheat via respiration through the animal functioning.

The flow of matter in ecosystems

The main chemical elements of life are carbon,nitrogen, phosphorus, oxygen and hydrogen.All these elements cycle through the living and non-living components of an ecosystem. Hydrogen andoxygen are usually referred to in the water cycle.These cycles are called biogeochemical cycles.

Ecosystems are complex. Appreciation of how they work has enabled the removal of dangerouschemicals such as DDT from our lives, and allowedfor the development of sustainable agriculturalpractices.

Carbon Dioxide + Water + Solar Energy =

Glucose + Oxygen

Secondary ConsumersGalaxias

Primary ConsumersCaddisfly

ProducersDuck weed

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Nitrogen cycle

Nitrogen is essential for normal bodily functioningand is contained in proteins, enzymes, hormones andmany vitamins. Nitrogen deficiency in plants causesstunting and yellowing, and in animals and humansis a key indicator of poverty related malnutrition.

Nitrogen gas makes up 80% of the atmosphere, butin this form it cannot be utilised by most livingorganisms. Nitrogen-fixing bacteria and some formsof blue-green algae can convert atmospheric nitrogeninto nitrates, and make them available to plants.

Legumes such as acacias, beans, peas and cloversform a symbiotic relationship with the bacteria inspecial nodules on their roots. This enables them to‘fix’ nitrogen into the soil, in the form of nitrates.These plants, as well as others, can then utilise thenitrogen.

The death of living organisms allows decomposerssuch as bacteria to break down the nitrogen from deadproteins into ammonia, which ultimately is available toplant roots as nitrogen, repeating the cycle.

Phosphorus cycle

Phosphorus is an essential nutrient of plants andanimals, where it is important for cellular respiration,cell membranes, as a component of DNA and RNA,and in teeth and bones.

Phosphorus cycles very slowly, beginning with theslow breakdown and weathering of rocks containingphosphate. The phosphates dissolve in soil waterwhere they are taken up by plant roots. These plants are then consumed by animals thatutilise the phosphorus in their metabolism.

When the animals or plants die, they are brokendown by decomposers in the ecosystem, making thephosphorus available again in the soil for a newcycle. Bird excreta and fish by-products aresignificant contributors to phosphorus levels in soiland water.

The cycling of key nutrients necessary for plant and animal growth are called biogeochemical cycles. This is because the nutrients pass through living and non-living components of the ecosystems via chemicalreactions during the cycles.

The key cycles are the nitrogen, phosphorous and carbon cycles. The hydrological cycle and sulphur cycle areoften included as they directly and indirectly impact upon the other cycles.


N u t r i e n tC y c l i n gN u t r i e n tC y c l i n g

Atmospheric Nitrogen N2

Nitrogen fixing bacteria

Bacterialdenitrification N2

Ammonium in soilNH4

AmmonificationNH3

Death anddecomposition

Animal excretions

Protein synthesis in plants

Consumption by animalsAnimal protein

Nitrates in soilNO3

-

Phosphates in rocks,fossils, guano

Phosphatefertilisers

Phosphates in soil,rivers, etc.

Decomposers

Up-take by plants

Bones, shells, excretaand ocean sediments

Runoff to lakes,oceans

Consumption byanimals

Animal excretionsand death



The carbon cycle

Carbon is the basic building block of carbohydrates,fats, proteins, DNA and RNA. Carbon dioxide (CO2)comprises 0.036% of the atmosphere. Most carbonon Earth is stored in ocean floor sediments andcarbon-rich organic rocks such as coal and peats.

The cycle commences with the process ofphotosynthesis. Atmospheric carbon dioxide isconverted into complex carbohydrates for thecreation of new plant tissue. Oxygen is released as aby-product. CO2 is also soluble in water, where it isavailable to water plants and algaes. CO2 in the formof carbonates react with calcium to produce calciumcarbonate, for the production of marine organismshells and skeletons.

Carbon dioxide is returned to the atmosphere in anumber of ways:

• Respiration by animals consuming oxygen and releasing CO2

• Respiration of decomposers or predators feedingon living or dead plants

• Burning of fossil fuel reserves releases CO2 and other carbon rich gases

• Volcanic eruptions • Burning of trees and plants as firewood

or for land clearing• Weathering of carbonates such as limestone

ReferenceMiller, G. Tyler (1996) Living in the Environment:Principles, Connections and Solutions. Wadsworth, USA.

C A S E S T U D YAlgal blooms in the Gippsland Lakes

Blue-green algae were one of the Earth’s firstorganisms to photosynthesise. They are believed tobe responsible for our oxygen rich atmosphere. They are naturally occurring in our waterways, andthere are many different species. Some producetoxins that can be harmful to humans and animals.Algal blooms occur when there is excess nutrients inthe water. All plants rely on nitrogen, carbon andphosphorus to grow.

Eutrophication is the process where excess nutrientssuch as phosphorus and nitrogen allow for theexplosive growth of water plants and algae, includingblue-green algae. Dissolved oxygen levels fall asthese organisms die and are decomposed. Thischanges the nature of the water, making it difficultfor fish and other aquatic organisms to survive.

Algal blooms can also affect the tourism industry ofthe Gippsland Lakes and as major blooms appear tobe occurring more frequently this is a major concernfor the region.

Nitrogen and phosphorus are soluble in water, andcan be easily lost from land-based ecosystems intorivers, streams and lakes. Phosphorus levels are highin irrigation runoff water, transported on soilparticles. Sewage is another source of excessphosphorus. It is thought that carp may disturb thelakes sediments, releasing phosphorus.

Managing phosphorusNow that the role of phosphorus in algal blooms hasbeen identified, the task is to reduce the loads fromcatchments into the lakes. It is important to maintainhealthy streamside vegetation on public and privateland to minimise soil erosion. Other methods such asbetter sewage treatment and replacing septic tankswill also help. Individuals can help by cleaning upafter their dogs and gardening in an environmentallyfriendly manner. Boat users on the Lakes need toensure safe disposal of boat toilets into pump outfacilities.

Referencewww.gcb.vic.gov.au/gippslandlakes/documents/L6algal.pdf

Animal Waste

AnimalConsumptionDecomposers

Fossil Fuels

Plant Tissues

Fire

CO2

Respiration

Death


Pest plants and animals are organisms deliberately or accidentally moved from their own ecosystems andintroduced to another. They are considered a pest because they impact negatively on natural and agriculturalresources. It is unlikely that we will rid our environments of all introduced species. Management of pest plantsand animals is often necessary to give ecosystems a chance to recover.


P e s t P l a n t sa n d A n i m a l sP e s t P l a n t sa n d A n i m a l s

Types of pests

WeedsThere are four categories of weeds in Victoria:

1. State prohibited weedsThese are weeds that either do not occur in Victoriaand pose a significant threat if they were toestablish or if present in Victoria, pose a significantthreat and eradication is considered feasible.

2. Regionally prohibited weedsWeeds that are not widely distributed in a region,but are capable of spreading further. Eradicationfrom the region is considered a possibility.

3. Regionally controlled weedsWeeds that are usually widespread in a region,that have sufficient impact. Control to preventfurther spread is considered important.

4. Restricted weedsPlants that pose an unacceptable risk of spread ifthey were sold or traded.

Feral animals These are usually domestic animals that haveescaped into the wild or were introduced afterEuropean settlement, e.g. foxes, rabbits, pigs, goats.

Agricultural pestsMany species of insects and nematodes.

Environmental weeds Plants that have naturalised and impact upon thevalue of native bush land. These can be introducedfrom overseas or other areas of Australia.

Marine pestsIntroduced marine pests are species moved generallyby human activities to an area outside their naturalrange, and that threaten human health, economicvalues or the environment.

Native animals as pestsSome native animals have adapted well to changingland use patterns and are considered agriculturalpests, e.g. wombats, kangaroos, corellas.Restrictions on controlling these animals apply.

Common pests of Gippsland

WeedsBlackberry, willows, ragwort, bridal creeper, thistles,cape broom, gorse, capeweed.

MammalsFoxes, deer, rabbits, wild dogs.

FishMosquito fish, carp.

BirdsBlackbirds, starlings, Indian mynas, sparrows.

MarineNorthern pacific sea star.

Pest ecology

PlantsOrganisms in ecosystems have particular roles forexample producers or consumers. If a plant isintroduced into a new ecosystem it must be able toreproduce to survive. If the new environment fallswithin its limits of tolerance, e.g. it is not too cold ortoo salty, the plant will find a niche grow to maturityand reproduce. Once actively reproducing the plant isconsidered naturalised.

As a producer it will now be in a foreign food web. To perform the ecological functions of energy andmatter transfer, it will need consumers to eat it anddecomposers to release the organic compounds andminerals back into the ecosystem – for use by otherproducers. If nothing eats it or breaks it down it candominate the landscape, locking up valuablenutrients and energy and actively causing theecosystem to function poorly. The next step of thesuccessful invader is to find a method of dispersal toinhabit more areas and ecosystems.

The rise of the blackberry to pest plant statusoccurred as European settlers planted it for food.Birds and foxes fed on the berries and excreted theseeds as they travelled, and a moderate climateenhanced its spread. In Europe, the blackberrys dieback in winter, which helps to control its growth.



AnimalsMany pest animals were introduced for humanpurpose by settlers in Victoria. The AcclimatisationSociety of Victoria, whose sole purpose was tointroduce foreign animals, performed someintroductions such as the house sparrow and theblackbird. They also released game animals onPhillip Island in the 1960’s to attract hunters.

Some members thought that the Australian bush wastoo quiet by day, and would like to hear thechattering of monkeys in the trees! Rabbits wereintroduced several times unsuccessfully before theirsuccessful introduction in Geelong in the 1840’s.

Some pest animals such as goats, dogs, cats andpigs were domesticated animals that were lost ordumped, and managed to successfully adapt toindependent conditions.

Finding a niche for a pest animal often means animpact on predator prey relationships or competitionfor resources . Introduced animals can also spreaddisease.

Management of pest plants and animals

It is unlikely that we will eradicate pests completelyfrom our ecosystems. One of the aims of pestmanagement is to reduce the impact of pest invasionson biodiversity by reducing their numbers. With pestplants, physical removal is a common practice, suchas willow removal in our waterways. With animals,this often means culling species such as foxes.

Biological controlBiological control refers to the utilisation ofbiological agents, such as diseases or predators of apest taken from its country of origin.

C A S E S T U D YEuropean Carp

Carp belong to the family of fish called cyprinids andare native to Asia. They are close relatives of thecommon goldfish. Carp were originally introduced inthe 1960’s to stock farm dams, but the practice hassince been banned, however they still entered ourriver systems. The Murray Darling Basin has beeninfested with the carp, as have the Gippsland Lakesand all of their tributaries.

Carp have a higher tolerance to variations in waterquality than many of our native fish; and canincrease turbidity in slow flowing water due to theirfeeding on lake and river floors. They are prolificbreeders and can out compete native fish for food.Carp have also been associated with bank erosiondue to their feeding on bank vegetation.

Although an introduced species, Carp are a resourceand need to be managed accordingly. Carp can beharvested and used for bait, fertiliser and humanconsumption. However, Carp have respondedpositively to already stressed aquatic ecosystems.One of the best tools in reducing their impact is toensure that rivers and streams are in peak condition,and provide suitable habitats for our native fish.Currently there are no known sightings of Carp in thehealthy rivers of Far East Gippsland.

Waterwatch run ‘Catch a Carp’ days each year in theGippsland region, contact your local Waterwatch forinformation.

Resources

Co-operative Research Center for Australian Weed Managementwww.weeds.crc.org.au

Biotechnology Australia online school resourceswww.biotechnology.gov.au


Invertebrates are animals without backbones; they include insects, worms, snails, shrimps, water fleas andmore. ‘Macro’ means visible with the naked eye. Many aquatic invertebrates are called macroinvertebrates.They form an important part of the food chain. Their survival depends on appropriate water quality andhabitat. By sampling and identifying macroinvertebrates at different locations, we have a clearer idea aboutthe ‘health’ of the waterway.


MacroinvertebratesMacroinvertebrates

Why are they important?

Macroinvertebrates form an important part of theaquatic food chain. Sunlight is converted to energyby aquatic plants and algae. The plants are theneaten by invertebrates, which are in turn eaten bylarger invertebrates, which are eaten by fish, birds,frogs etc. Many macroinvertebrates also helpdecompose organic material.

Where do they live?

Moving water such as rivers, creeks and streamsMoving water is different from still water, andorganisms must be adapted to these differentconditions. Within a river or stream the water flows vary.

Habitats include:

• Riffles – the shallow rocky parts of rivers with fastflow

• Pools – deeper and slow flowing water• Runs – the transition between pools and riffles

The organisms in riffles are adapted to faster-flowingwaters, whereas the animals in pools are adapted toslower-moving water. Organisms living in movingwater must be able to ‘hang on’. They havestreamlined bodies, or special hooks or suction-typeattachment structures. Some organisms buildstructures to keep themselves in place such ascaddisfly larvae.

Still water such as wetlands, backwaters, lakes and poolsOrganisms in still or slow-moving water don't have tohang on. Pools in streams are considered slow-moving waters, which means that these organismsmust actively search for food. They are notnecessarily streamlined; they have adapted to move.Some have adapted to live on the surface, some liveon the bottom, some live in the leaf litter around theedges, and others burrow into the soft sediments.You often see a wider range of sizes and shapesamong the organisms in still or slow-moving water.

Macroinvertebrates as indicators of waterway heath

In ecosystems, high diversity or number of differentspecies is an indication of a stable or healthysystem. In order to survive, macroinvertebrates needspecific ranges of environmental conditions such astemperature, oxygen levels, pH and salinity. Reduced water quality can affect macroinvertebratesby decreasing macroinvertebrate diversity, leavingonly those species tolerant of poor water quality.



Other factors that lead to a reduction in speciesdiversity include:

• Pollution

• Increased sediments that reduce light penetrationto aquatic plants and smother gravel habitats

• Removal of riparian vegetation, which suppliesfood in the form of organic material such as leavesand bark and keeps water temperatures cool

• Removal of snags or woody debris. This provides habitat and moderates water flow

• Barriers such as dams, which can alter thenatural, flow regime

• Increased nutrients from catchment run-off willchange the ecosystems

C A S E S T U D Y The Crafty Caddis Fly

The adult caddis fly of theTrichoptera Order is similarin appearance to otherflying insects. They areshort lived fast fliers thatare mostly seen at nightgathering around lightsnear streams and ponds.The larvae of the Caddis flyhowever are verydistinctive. Many buildthemselves a small tubular

house out of sticks, stones, plant material or sand.The larva holds itself in the tube with hooks comingfrom the end of its abdomen. The larvae can anchor itself or have a portable case itcarries with it. So when collecting macroinvertebrateswatch out for tiny sticks or stems that appear to haveheads or legs and may be swimming along, theyprobably contain the crafty caddis!

ReferenceHawking, J.H., Smith, L.M., Le Busque, K. (2004onwards) Identification and Ecology of AustralianFreshwater Invertebrates.www.clw.csiro.au/ColourWebGuide/

Referenceswww.vic.waterwatch.org.au

Gabas, Stephan. Aquatic ecosystem assessmentusing Macroinvertebrates Organisms as aBioindicator. SGS Australia.

Resources

Waterwatch Victoriawww.vic.waterwatch.org.au


Biodiversity is the variety of all living things; the different plants, animals and microorganisms, the geneticinformation they contain and the ecosystems they form. Unlike resources such as oil and coal, biodiversity isrenewable – but only if we use it and nurture it wisely.


M a n a g i n g o u rB i o d i v e r s i t yM a n a g i n g o u rB i o d i v e r s i t y

Gippsland’s biodiversity

In Victoria a Biodiversity Strategy was launched in1997. It highlights 21 ‘bio-regions’ that identify thepatterns of ecological characteristics in thelandscape or seascape. Bio-regions are areas ofsimilar vegetation, topography and climate. The bioregions of the Gippsland area include:

1. Victorian Alps2. Highlands – Southern Fall3. Highlands – Northern Fall4. Coastal Plains – Gippsland Plains5. Wilson’s Promontory6. East Gippsland Uplands7 East Gippsland Lowlands8. Terrestrial Wetlands9. Rivers and streams10. Coastal zone

These bio-regions consist of many differentecosystems which are identified as broad vegetationtypes. For example, the Gippsland plain bioregionhas fourteen broad vegetation types including PlainsGrassy Woodlands and Swamp Scrub complexes.There are less than 2% of the original areas left ofthese broad vegetation types – mostly because theseecosystems were easily cleared for agriculture.

Threats to biodiversity

Any action that causes the reduction in the numberof different species in an ecosystem, or the loss of anentire ecosystem, is termed a threatening process.Threatening processes include human activities suchas land clearing, pollution and processes associatedwith European settlement, such as introduced plantsand animals, changed fire regimes and erosion.

The goals of biodiversitymanagement in Victoria

The broad goal in Victoria is to see a reversal of thedecline in the amount and quality of our vegetation,with no net loss. Other goals include:

• that ecological processes and the biodiversity thatdepends upon our terrestrial, freshwater andmarine environments are maintained, and in somecases restored (such as creek side vegetation)

• there should also be no further decline in theviability of any rare species or ecosystem

Managing biodiversity

All levels of government and the community areresponsible for the management of biodiversity. At a federal level there is a National Strategy for theconservation of Australia’s Biological Diversity. At the state level, the Flora and Fauna Guarantee Act1988, governs the management of plants andanimals. Its Biodiversity Strategy outlines the goalsof the state government and the methods ofmaintaining biodiversity.

At a local level, there are council vegetation clearingby-laws and the Victorian Planning ProvisionFramework. Organisations such as CatchmentManagement Authorities work with local councilsand landholders to restore streamside vegetation.

Volunteer programs such as: Land for Wildlife, the Good Neighbour Initiative, Waterwatch, FieldNaturalist Clubs, Parks Victoria Friends groups, andThreatened Species Networks, all work together tomonitor and restore biodiversity in Victoria.

There are over 700 Landcare groups whose membersare farmers that realise that healthy ecosystems onfarms mean healthy farms and better productivity.

School involvement in Waterwatch is a great way tomonitor Victoria’s wetlands, rivers, streams andcoastal zones.



C A S E S T U D YGippsland’s threatened species

There are many animal species in Gippsland that areconsidered threatened due to loss of habitat.Examples include:

Baw Baw Frog – Philoria frostiThe Baw Baw frog is only found in an 80 km2 area onthe Baw Baw plateau. It needs a special habitat tosurvive. Unlike most tadpoles, Baw Baw tadpoles donot eat. They hatch with a yolk sac that feeds themuntil they become frogs. They do not swim either;developing into frogs under vegetation and leaf litter,where there is little free flowing water. It is thoughtthe original population was between 20,000 and 30,000 frogs. Now less than 600 remain. The causeof decline for the Baw Baw frog is unknown, butcould include climate change, pollution, habitatdestruction or disease.

White-bellied Sea-eagle – Haliaeetus leucogasterThe White-bellied Sea-Eagle is a large bird of preywith a low Victorian population. It is estimated thatapproximately 25 pairs live around the GippslandLakes, 25 pairs around Corner Inlet and a further 50pairs throughout the rest of Victoria.

The threatened status of the species can mostly beattributed to human disturbance including habitatfragmentation and nest disturbance.

Although there is little direct evidence, other possiblethreats include: poisoning during pest animal controlprograms;; deliberate shooting; eggshell thinningbecause of the past use of DDT; and food chaincontamination by heavy metals. Immediate objectivesby natural resource managers include gaining anaccurate estimate of the total breeding population,identifying and protecting all known nest sites; andmaintaining and improving areas of suitable habitat.

(Source: Department of Sustainability and Environment:Approved Action Statement For Animals No. 60)

The Giant Gippsland Earthworm – Megascolides australis The Giant Gippsland Earthworm is one of the world'slargest earthworms. It is restricted to a small area inthe Bass River Valley of South Gippsland bounded by

Loch, Korumburra and Warragul. Recent studiesshowed that the worm was only found in 6% of thearea surveyed and that over 80% of the worms werefound within 40m of creek banks!

It is considered vulnerable, meaning that the speciesmay risk extinction if there is continued pressure onthe population through habitat destruction.

Therefore the most important way of conserving theearthworm is to protect its habitat, stream banks.

Other threatened fauna species include:Barred GalaxisGiant Burrowing FrogEastern QuollHelmeted HoneyeaterHemiphlebia DamselflyHooded PloverLarge Ant Blue ButterflyLeadbeater’s PossumLittle TernLongfooted PotarooRegent HoneyeaterSouthern Right WhaleSpot-Tailed QuollTasmanian PademelonWarragul Burrowing crayfish

Referenceswww.dse.vic.gov.auwww.wwf.org.auwww.birdsaustralia.com.au

Resources

Victorian Museumwww.museum.vic.gov.au/bioinformatics/

Department of Sustainability and Environmentwww.nre.vic.gov.au/plntanml/biodiversity/

Australian Natural Resources Atlasaudit.ea.gov.au/ANRA/atlas_home.cfm

Australian Museum Websitewww.austmus.gov.au/biodiversity/


Fire, as a natural event, has been a part of Australian ecosystems for millions of years. Many of our plantsand animals have evolved strategies to ensure they recover from fire. Aboriginal use of fire has beenrecorded from earliest European colonisation. Early pioneers sited low intensity fires that were used forcooking and warmth. Aboriginal people also managed grasslands by burning to encourage grass growth andto assist in hunting.


F i r eF i r e

Fire in Gippsland

Fire has different impacts on landscapes dependingupon the fire regime. There are three variables thatimpact on fire regime, the intensity of the fire, howfrequently the fire burns and what season the fireoccurs. Severe fires such as those in 1939 and 2003occurred during extremely hot summers after manyyears of below average rainfall.

Although devastating to people, property,infrastructure and animal populations, theenvironment will regenerate. However, fires at highfrequencies do have the ability to change ecosystemcomposition.

If plants that generate from seed do not grow tomaturity and produce seed before the next fire, thatspecies can be lost from an ecosystem.

The effects of fire on our catchments

BiodiversityThe immediate impact of fire is the loss of ourvegetation. However, grass trees soon burst intoflower and seed. Eucalypts such as Eucalyptusradiata, shoot buds from specialised epicormic budsbeneath their thick bark. Acacia species may regrowfrom seed or from root suckers after fire.

Animal populations loose their habitat after fire. Fire of low intensity may allow for species such aspossums to shelter in tree crowns. Many insects and

spiders are killed, but flying insects may escape.There is no doubt that the habitat changes caused byfires impact upon our animal species in the form ofloss of food and shelter. A regrowing forest thenprovides new habitat and food chains becomeestablished again.

Soil The soil undergoes many changes after a fire. Lowintensity fires may sterilise the soil, destroying plantpathogen and leaving the soil ready for germinationof new plants. High intensity fires create an ash bedthat is high in plant nutrients such as nitrogen andphosphorus. Heavy rain after fire can lead toleaching of nutrients and erosion before plantsrecolonise and stabilise the soils.

Water Fires can impact heavily on water quality andquantity. After fire, soil and ash are mobile andrainfall may wash these into waterways, impactingthe aquatic ecosystems. After the fire there may beincreases in surface runoff into streams and rivers,increasing flows.

After the forest regenerates the actively growingtrees have a high demand for water, reducing thesurface and groundwater flows from a catchment.



Ecosystem recovery from fire

In the first few weeks after a fire, plants begin torecover. Eucalypts sprout from epicormic buds andwattles and peas grow from root suckers. Many fastgrowing herbaceous plants appear. These are vital inquickly trapping nutrients and stabilising soils. Over time these species are out competed. Insects and mobile animals begin to return to thearea and birds are attracted to flowering plants.

As the forest matures, many species are outcompeted as there are limited amounts of nutrients,space and light available. The species diversitydecreases as the forest begins to resemble thestructure of the original vegetation type.

C A S E S T U D Y Fire and endangered species

Ecologists have found that plant and animals vary intheir requirements of fire frequency. Some speciesrequire frequent fires, but others such as themountain pygmy possum could perish under a regimeof frequent fires. One of their key food sources, the mountain plum pine, is highly fire sensitive.

The eastern Victorian fires in 2003 burnt more thanone million hectares. The fires burnt in significantareas of the Victorian alpine region, including theAlpine National Park and Snowy River National Park.It is estimated that a number of threatened specieshave been affected by the fires.

The fires may have impacted upon threatenedspecies such as; the mountain pygmy possum, tigerquoll, brush-tailed rock wallaby, spotted tree frog,long-footed potoroo, eastern wallaroo, Alpine treefrog, Alpine water skink, Alpine she-oak skink, Alpinebog skink and the Booroolong frog.

Impacts range from changes in water quality to lossof habitat and food sources.

Resources

Parks Victoriawww.parkweb.vic.gov.au

Victorian National Parks Associationwww.vnpa.org.au

Department of Sustainability and Environmentwww.dse.vic.gov.au


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