What this lesson teaches
I can evaluate the ecosystem services of karst landscapes and human impacts on them.
Syllabus 9173, Topic 2.2, 2. Karst Landforms in the Humid Tropics. What is the importance of karst landforms in the humid tropics?
Make a guess
A farm far from a cave lets fertiliser wash into a sinkhole. Can this harm the cave's wildlife?
- Not unless the farm is directly above the cave.
- No. Pollution matters at the cave entrance.
- No, because limestone filters out pollution.
- Yes. Water travels fast underground, little filtered.
Show the answer
Yes. Water travels fast underground, little filtered.
Karst drains through connected channels, so pollution entering a sinkhole can reach caves and springs far away quickly.
Karst provides water, habitats and cultural value, but its underground drainage lets damage spread far beyond where it starts.
Karst aquifers supply water to homes, farms and industry. This is a provisioning service. Forests and caves support rare species and nutrient cycling, which are supporting services. Karst forests also regulate water and protect soil, but fast underground channels make floods and pollution hard to predict.
Dramatic hills and caves attract tourists and hold spiritual and cultural value. These are cultural services. Limestone is also quarried for building, but quarrying destroys landforms and habitats forever.
Quarrying and blasting destroy hills and change drainage. Clearing forests changes soil and water. Fertiliser, sewage and industrial waste can enter sinkholes and travel fast underground with little filtering. Pumping groundwater can lower water levels and dry out springs.
Tourism can pay for protection and local jobs. But crowds, lighting, rubbish and touching formations can harm cave life and delicate deposits. So judge how intense the activity is and how it is managed, not just whether tourists are there.
Protection must cover the whole connected catchment, not just the cave entrance. Controlled access, water-quality management, limits on quarrying and local participation can protect services, but enforcement and other ways to earn a living affect success. A gain for one group may bring water or cultural losses for another.
- Provisioning
- Water from karst aquifers.
- Cultural
- Tourism, recreation and spiritual value.
- Key risk
- Pollution travels fast underground with little filtering.
Step by step
Name the service
What is the benefit, and who relies on it?
Trace the pressure
How does the activity change rock, water or habitat?
Weigh the trade-off
Compare gains and losses across groups.
Real examples to use
Ha Long Bay, Vietnam
A UNESCO World Heritage Site since 1994, its limestone towers attract millions of visitors, bringing income but also pollution from boats and development.
Worked example: Protecting South China Karst
UNESCO stresses protecting the upstream catchments and underground links of South China Karst. A cave's boundary cannot keep its water clean if pollution enters connected drainage outside it.
Watch out for this
Pollution can only reach a cave if it is dumped at the entrance.
Water carries pollution through cracks, sinkholes and underground streams from far away.
Check your understanding
Which measure best tackles a cave's polluted groundwater?
- Fencing the cave entrance to keep visitors out.
- Treating the water at the cave's main pool.
- Reducing pollution across the connected recharge area.
Show the answer
Reducing pollution across the connected recharge area.
Yes. That is where the water comes from.