Land Cover, Climate and Biodiversity - TCE Geography (Tasmania)
“Land cover change alters climate through albedo and the carbon cycle, and reduces biodiversity, with feedbacks that drive further change.”
Changing land cover alters global climate by changing surface reflectivity (albedo) and by releasing or storing carbon, and it reduces biodiversity by destroying and fragmenting habitat. These effects feed back on each other, so climate change and biodiversity loss in turn drive further land cover change.
What this dot point is asking
Land cover transformation is not just a local change to the surface; it reaches up into the atmosphere and out across ecosystems, altering two global systems at once: climate and biodiversity. Understanding these interrelationships, and the feedback loops between them, is the analytical heart of the land cover unit.
The first pathway is the carbon cycle. Vegetation, especially forests, stores large amounts of carbon in trees and soils and removes carbon dioxide from the atmosphere through photosynthesis, a process called carbon sequestration. When forests are cleared or burned, that stored carbon is released as carbon dioxide, and the lost vegetation can no longer sequester carbon. Deforestation is therefore a major source of greenhouse-gas emissions and a reduction in the planet's capacity to absorb them, intensifying the enhanced greenhouse effect and global warming. Conversely, protecting and restoring forests, peatlands and wetlands strengthens carbon sinks.
The proportion of incoming solar radiation that a surface reflects back to space. Light surfaces such as ice and desert have high albedo and reflect strongly; dark surfaces such as forest and ocean have low albedo and absorb more, warming the surface.
The second pathway is surface reflectivity, or albedo. Different land covers reflect different amounts of sunlight. Replacing dark forest with lighter cropland can raise albedo and locally cool, while clearing bright snow or ice exposes darker ground or water that absorbs more heat, warming the surface. Land cover change also alters the water cycle and local climate: forests recycle moisture into the atmosphere through transpiration, so large-scale deforestation can reduce rainfall and dry regional climates, as is feared for parts of the Amazon. Urban surfaces absorb and retain heat, creating urban heat islands.
The third pathway is biodiversity. Land cover change is the leading driver of biodiversity loss worldwide. Clearing and converting natural vegetation destroys habitat, while roads, farms and cities fragment what remains into isolated patches too small to sustain many species. Loss of biodiversity weakens ecosystem services such as pollination, water purification, soil formation and carbon storage, which feeds back on both climate and human wellbeing.
The relationships run both ways. Land cover change drives climate change and biodiversity loss, but climate change (through warming, drought and fire) and biodiversity loss in turn cause further land cover change, such as forest dieback or invasion by new species. These feedback loops can accelerate change, which is why early intervention matters.
Tasmania shows these processes locally. The Tasmanian Wilderness World Heritage Area stores carbon in tall wet eucalypt forests and ancient Gondwanan vegetation, but warming and dry-lightning fires have burned fire-sensitive species such as pencil pine that may never recover, converting forest to other cover and releasing carbon, a clear climate-biodiversity feedback. Historic clearing of Midlands woodland fragmented habitat and reduced biodiversity. Offshore, ocean warming linked to global climate change has driven the long-spined sea urchin south, where it overgrazes giant kelp forests, transforming productive reef into barren ground and collapsing local biodiversity and fisheries. Globally, Amazon deforestation releases carbon, threatens rainfall recycling and destroys some of the richest biodiversity on Earth.
This pervasive human influence means truly natural environments no longer exist; geographers describe the result as anthropogenic biomes, landscapes whose character is now defined by human modification. Recognising this reframes management: the goal is not to restore an untouched baseline but to manage modified systems for climate stability and biodiversity.
A common stimulus is a diagram of forest carbon stores and fluxes, sometimes with figures. Work it in steps.
Step 1: separate stores from fluxes
Identify the stores (carbon held in biomass and soil) and the fluxes (arrows showing uptake by photosynthesis and release by respiration, decay or burning).
Step 2: read the balance
A healthy forest takes up more than it releases, acting as a net sink. If uptake is labelled units and release units, the net sink is units.
Step 3: model the disturbance
Show what clearing or fire does: the release flux spikes (stored carbon is liberated) and the uptake flux collapses (no trees to photosynthesise), flipping the forest from sink to source.
Step 4: connect to the wider system
Link the released carbon to atmospheric warming and the lost vegetation to habitat and biodiversity loss, naming the feedback. Reading the diagram and converting it to system logic is what the marks reward.
Answers that discuss climate change and biodiversity loss in isolation miss the geography. The two are linked through land cover and through feedback loops: forests store carbon and host biodiversity, so losing them harms both, and warming then drives further loss. Always connect the systems.
For TCE assessment, explain the mechanisms (carbon cycle, albedo, water cycle, habitat loss and fragmentation) by which a specific land cover change affects climate and biodiversity, identify the feedback loops, and support the analysis with a Tasmanian case such as fire in the World Heritage Area and a global case such as Amazon deforestation. Use the concept of anthropogenic biomes to frame why management of modified environments is now unavoidable.
Exam-style questions
Questions in the style of TASC exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Practice8 marksUsing a labelled diagram of the forest carbon cycle, explain how deforestation contributes to climate change.Show worked answer →
An 8 mark source response must use the diagram to drive a clear causal explanation.
Read the diagram. Identify the stores (carbon in trees and soils) and the fluxes (carbon dioxide taken up by photosynthesis, released by respiration and burning). Refer to labelled arrows rather than writing generally.
Explain the mechanism. State that intact forest sequesters carbon dioxide and stores it; clearing or burning releases that stored carbon to the atmosphere and removes the sink, so atmospheric carbon dioxide rises, intensifying the enhanced greenhouse effect and warming.
Add a second pathway if room allows: loss of forest can reduce transpiration and rainfall recycling, drying regional climate. Markers reward direct use of the diagram, the sink-and-source logic, and correct terminology.
Practice12 marksAnalyse how land cover change affects both climate and biodiversity, and evaluate the view that the two impacts are linked through feedback loops. Use a Tasmanian example and a global example.Show worked answer →
A 12 mark response needs both impact pathways, the feedback argument and a judgement.
Mechanisms. Explain the carbon cycle and albedo pathways to climate, and habitat destruction and fragmentation as the leading driver of biodiversity loss.
Feedback evaluation. Argue the links run both ways: in the Tasmanian Wilderness World Heritage Area, warming and dry-lightning fire kill fire-sensitive pencil pine, releasing carbon and destroying biodiversity, which then alters cover further. Globally, Amazon deforestation releases carbon, weakens rainfall recycling and destroys biodiversity, with dieback as a feared feedback.
Judgement. Conclude that climate and biodiversity impacts are tightly coupled through land cover and feedback loops, so they cannot be treated separately. Markers reward the mechanisms, a paired local and global case, and explicit feedback reasoning.