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Ecosystems at riskLimestone Caves
Fieldwork at Yarrangobilly Caves
Map of Yarrangobilly Caves Map of Australia’s Limestone Caves
Page | 1Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
General Information
Limestone caves areas are known as “Karst” areas. The caves are a Karst system with about 320 known caves in varying stages of development and
differing levels of importance. This Karst is 12kms long and 1.6kms across. Each cave has its own ecosystem functioning and are managed accordingly.
The cave ecosystem is part of a larger catchment. The ecosystem within each cave is linked to the upper catchment by the flow of water. What happens
above the caves will have an effect on the caves themselves.
What is Karst?
Karst is the name given to limestone cave systems across the world.
They are unique ecosystems with some endemic flora and fauna (found nowhere else in the world)
Very little Karst can be found in Australia. The Nullabor plain is the largest Karst system in the Southern Hemisphere
Caves are a time capsule of past conditions. Studies of cave decorations have been used to determine past climate change
Why is this ecosystem at risk/fragile? The cave system is very susceptible to change. Because it is so stable in terms of abiotoc factors (physical features- temperature, rainfall, humidity,
light) it cannot withstand change no matter how small. It is always, moist, dark and humid without diurnal (daily) or seasonal variations so everything
has evolved without the ability to cope with change
Each system is isolated, we say they are “islands in the sky” The nearest system is the Blue Waterholes. Caves system about 30kms away. So if
animals and plants cannot travel from one system to another
The caves are affected by the happenings in the surrounding area not just within the caves. For example the upper catchment Pine plantation had a
big effect on water flow and hence the caves environment
Organisms have become very specialised with reduced capacity to withstand change.
Spatial Patterns and DimensionsPage | 2
Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Using geographical tools and skills collect data for
Site Altitude Latitude Longitude
Yarrangobilly Village Site/ Wild cave 35 39S 148 28E
North Glory Cave 35 43S 148 29E
Biophysical Interactions
Dynamics of weather and climate
Using the data in the graph above tabulate the monthly temperature data for Kiandra and inside the cave at Yarrangobilly.
Jan Feb Mar Apr May June July Aug Sep Oct Nov Dec
Mean Daily Temperature at Kiandra
Mean Daily Temperature inside cave
Biophysical Interactions
Page | 3Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Using geographical tools and skills collect data for
* Air Temperature *Relative Humidity *Light *Soil pH ( at the entrance only)
Characteristic Instrument & Unit
Entrance Twilight Dark
Air temperature Thermometer 0C
Relative humidity Hygrometer %RH
Light Meter lux
Slightly darker at night than daytime Total Darkness0 Lux
Never varies
Soil pH Universal indicator
Strongly Alkaline
(gained from historical testing)
Strongly Alkaline
(gained from historical testing)
Animals present Evidence Kangaroos, Wallabys, Lizards, Snakes, Birds
Cockroaches, Spiders, Springtails, Cave Cricket
Translucent spider, Blind beetle, Cave cricket
Plant diversity (number)
Quadrat Larger diversity, and numbers Moss, Lichen, Liverworts, Algae
Low diversity
Lampen Flora- artificially lit areasNo natural plants
*Mildew also
Plant height & % cover
Quadrat As for surrounding bushland- Mainly shrubs at entrance to 3m
100% coverage
5-10cm
50-70% coverage
NIL
NIL
Biophysical Interactions
Climate differences exhibited between the three ecosystems.
Page | 4Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Entrance Twilight Dark
Diurnal change
The temperature varies as per the outside surrounds.
Significant daily and yearly changes.
Minor Nil
Seasonal change Minor Nil
Annual change Minor Nil
Air Temp change Minor Nil
Overview Dark, damp & always humid. Further into the cave the more stable the climate becomes
General rule is that the Temperature in a cave is the average yearly temperature of the surrounding area
Page | 5Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Biophysical Interactions
Geomorphic and hydrologic processes
Many landforms develop from the breaking down of rock (weathering), the removal of the weathered material (erosion) and the deposition of the eroded material. Landforms include hills and valleys, floodplains, beaches, karst (limestone areas) and limestone caves.
Steps in Cave Development
1. Rain Water falls
2. Carbon dioxide from soil / air dissolves
3. Formation of acid groundwater
4. Limestone is dissolved by acid groundwater chemical weathering)
5. Caves develop
6. If water table drops the cave stops developing
7. Cave decorations (speleothems) begin to form. The deposition of calcite begins the formation of stalactites and stalagmites.
Page | 6Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Nature and rate of change which affects ecosystem functioning
Describe the general landscape.
Karst system surrounded by granite mountainous wet forest
Explain how limestone caves form.The area was under the ocean. Coral reefs formed.
About 300000 years ago there was uplift by tectonic forces.
As rainwater flows over the ground it combines with carbon from the plants forming a Carbonic acid which dissolves the limestone as it flows through small
cracks.
Over millions of years the cracks form into the caves.
Explain how speleothems (cave decorations) form.
Flow of water is the key.
Water drips off leaving a small ring deposit of calcite. Slowly this calcium builds up to lengthen the decoration.
As water drips onto the floor it leaves a buildup of calcite forming the stalactite decorations
Stalagmites grow from the floor up from the deposition of calcium carbonate from drops of water landing on the cave floor (below left).
Stalactites have formed along joint lines in the limestone where water has seeped through (below right).
Page | 7Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Vegetation
Entrance Twilight Dark
Native Trees Mountain GumMountain Ash
Native Shrubs Grevillia, BursariaTea Tree, Hakea
Native Grasses PoaWallaby
Native Herbs Buttercup
Other Liverworts, Moss, AlgaeLichen (50-70% coverage)
Lampen Flora(near artificial lights)
Introduced Weeds St Johns WartScotch thistle
Introduced Trees ElmPine
Caves generally:
Plant Biomass is 0.2kg/m2 which is very low (Rainforest is 45kg/m2)
There is a lack of sun light for photosynthesis so only a few small, specialised plants survive hence only a small number and type of
herbivores can live in the ecosystem
Page | 8Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Fauna
Entrance Twilight Dark
Wallaby Cave Cricket Translucent Spider
Wombats Cockroaches Blind Beetle
Birds Spiders Cave Cricket
Lizards Springtails
Snakes
Thylacine (Tasmania tiger) fossils indicate previous climatic conditions suited its habitation
Blind Harvestman Spider only found in the Harry Wood Cave- endemic very endangered
Fauna has unique physiological adaptations to survive in the dark, humid, moist cave environment: Long feelers, multiple long limbs
are an advantage. They have lost pigmentation, and have poor or no eyesight.
A behavioural adaptation is the Crickets move out to the entrance area to feed at night
Very specialised with reduced capacity to withstand change
Page | 9Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Human Impacts ( positive and negative)
Aboriginal history Yarrangobilly means "Teeth water"
Groups travelled through the area on way to mountains for summer
Caves would have been used for shelter. Wet & damp not suitable for permanent accommodation. Rough terrain made living here difficult
European history
Late 1800s first Europeans came to the area and discovered the caves
Glory farm- cattle farm set up homestead on Yarrangobilly River
Introduced Poplar and Elm trees
Trout were introduced to the river from Adaminaby area
1920 cave house was constructed for tourism
1950s prison labour from Cooma was used to develop infrastructure for visitation
1967 NPWS took over management. Discouraged visitation because could not handle the sewerage an wastes- was destroying the system
Page | 10Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Human Impacts ( positive and negative) Traditional and Contemporary management practices
List of the Human Impacts in this ecosystemComplete the table by listing the inadvertent human effects on this ecosystem and the management practices employed (both traditional and contemporary)
Human Impact Impact on the functioning of the ecosystem Management Practices Effectiveness of Management
Practices
Highway Road
Old road construction storage and dump site
Quarry- disused
Buildings, homestead, sewerage
Pine tree plantation
Page | 11Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Human Impact Impact on the functioning of the ecosystem Management Practices Effectiveness of Management
Practices
Land clearing
Camp ground / Fire places
Toilets-sewerage into river
Washing in river-
Garbage dumping
Feral animals
Page | 12Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Traditional and contemporary management practices
Upper Catchment Area
Maintaining the upper catchment area is very important in caves management. Any change in the water cycle will have an effect on the cave ecosystem. The cave ecosystem relies on the water flowing in to the caves for much of the energy and food supply.
Reductions in the amount of water will affect cave development. Replacing native vegetation with pine plantations reduced the water entering the caves. Pines use 17% more water than eucalypts.
Pollution has a big impact on water quality. Sources of pollution can be sediment from land clearing, animal faeces, sewerage, road dirt and oil, seepage from garbage tips. Natural Sink holes were used as garbage tips in the past
How are the caves and catchment being managed on a sustainable basis?
The Yarrangobilly caves are managed by National Parks and Wildlife Service (NPWS) under the Kosciuszko National Park Management Plan.
Caves are categorised according to their importance and access is determined accordingly. At Yarrangobilly there are 6 categories of caves, varying from “open to public” to “scientifically significant”. NPWS must manage both the caves and the catchment for the Yarrangobilly Karst system. 25% of revenue generated by tourism to the caves is returned into cave care programs.
Water flow is critical to the caves so its management is extremely important. The general belief is that once you allow visitation you sacrifice the cave. However due to historical visitation, there is an obligation to continue visitation into the caves. NPWS have included an education component with guided tours that play a critical role in the ongoing management of this fragile and at risk ecosystem.
Pathing has been installed outside cave entrances to help reduce the amount of dirt entering the cave via the feet of visitors. Lighting systems are continually being replaced with automatic energy efficient light system
NPWS staff must balance environmental and cultural heritage issues. For this reason they have retained the introduced Elms and Pines. NPWS produce their own Hydro-power on site replacing old diesel generators that use to leak oil into river. A new sewerage system (costing $1.5 million) which uses no chemicals was recently installed and it is located on granite site nearby- not on Karst. Local Poa grass uses up nutrients and provides a seed bank for regeneration works.
Feral Brumbies are kept away for the caves area with an active trapping and removal program in place.
Page | 13Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Cave Tour Notes:
Pure Limestone is milky or white
Limestone turns into marble when gets volcanic heat
Red colour is from iron picked up as water passes over rock with iron in it
Black colour is caused by bushfires. Some black staining from early visitors using kerosene lamps
Black bands caused by fires used to date age of cave
Moonmilk- bacteria reacts with limestone to form white growth
Water levels fluctuate
Calcite floats on water
Straws 6mm in diameter, hollow as water drips off leaves ring of calcite which is new growth. 98% turn into stalactites
Bacon water comes from side of cave and runs down wall
Bacon grows into Shawl and Shawl grows into Blanket
Helicitite turn up and around from roof
Column is Stalactite and Stalactite joined
392 Known caves
6 show caves with 5000 visitors per year
Jillabenan
is most decorated cave in Australia
2 million years old
Small cave with limited air flow.
Tour groups increase temperature and co2 which speeds up Lampenflora growth. When temperature increases the cave is closed
Jersey Cave 1.5 million years old
Glory Caves 100000 years old Least developed so self-guided tours in South Glory
Page | 14Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
Past Exam Questions & Examiner notes:
2013 HSC Geography Question 25 – Ecosystems at Risk“Assess the human impacts on the functioning of TWO ecosystems at risk”
General observations: Almost all students named 2 ecosystems. Many included spatial dimensions ( location, size, etc) The majority of answers were quite detailed Students seem to have found it easy to outline / describe human impacts on ecosystems and managed to include several for each ecosystem
Discriminators:Human impacts: These are many and varied and directly relevant to the ecosystems chosen
Simplistic coverage of impacts – list human actions eg. Dirt access roads, accommodation & buildings, sewerage pollution, farming, forestry, More comprehensive coverage of impacts;
human action effects of actioneg. Tourism sacrifice of caves loss of ecosystem
Human impacts on the functioning A lot of students didn’t address the term “functioning” Requires a greater depth of knowledge / understanding Explicitly talks about how the actions of humans impacts on the functioning of an ecosystem Functioning = energy flows, nutrient cycle’s, chemical transfer, photosynthesis, food chains, food webs, trophic levels, linkages, biodiversity, interdependence,
stability, structure, biophysical interactions, seral progression, succession, dynamic equilibriumAssess Judgement
Simplistic judgement – a statement like “ this impacts on the functioning of the ecosystem” with no follow up given Implied impact on the functioning of the ecosystem – not explicitly stated More comprehensive – makes a judgment about the impact of one human action on the functioning of an ecosystem – but doesn’t carry it through all examples of
human impacts Explicit, comprehensive judgement supported by evidence about the impact of human actions on the functioning of the ecosystem. Impacts are: positive, negative, devastating, destructive, minimal, extensive, damaging, disturbing, constructive….
Caves Ecosystem at Risk: Lotus Diagram
Ecosystems at Risk: Caves Study Lotus Diagram
Page | 15Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
1
Spatial Patterns
2
Weather & Climate
3Geomorphic and Hydrological processes
1.
Spatial Patterns
2
Weather & Climate
3Geomorphic and
Hydrological processes
4
Bio geographical processes
4
Bio geographical processes
ALPINE ECOSYSTEM AT
RISKYarrangobilly
Caves
5Adjustments in
response to natural stress
5Adjustments in response to natural stress
6. . Nature and rate of change which
affects ecosystem function
7Human impacts
Positive & negative
8Traditional and contemporary management practices
6. Nature and rate of change which affects ecosystem function
7Human impacts
Positive & negative
8Traditional and contemporary management practices
Page | 16Ecosystems at Risk: Caves Study Riverina Environmental Education Centre
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