Forest Ecosystems (Cambridge (CIE) IGCSE Environmental Management): Flashcards
Exam code: 0680
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Define deforestation.
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Define deforestation.
Deforestation is the removal of trees and the clearing of forested land.
Why is logging often the first step in deforestation?
Logging opens up forests to other activities, such as farming or mining.
True or False?
Selective logging causes no damage to the trees left standing.
False.
Machines moving through the forest can damage nearby trees during selective logging.
Why do slash-and-burn farmers move on to clear new forest?
Burning only temporarily increases soil fertility, so the nutrients quickly run out and farmers move on.
Subsistence farming is sustainable at a small scale but becomes destructive when grow.
Subsistence farming is sustainable at a small scale but becomes destructive when populations grow.
Why does commercial agriculture clear such large areas of forest?
Commercial agriculture keeps land clear permanently and uses large machinery that destroys vegetation.
How does road building lead to further forest loss?
New roads open remote forests to logging, hunting and land clearing, which triggers a chain reaction of forest loss.
How do hydro-electric power dams cause deforestation?
Hydro-electric power dams flood forests and valleys, so huge areas of woodland end up submerged under reservoirs.
True or False?
Climate change can make forests more vulnerable even without human clearing.
True.
Rising temperatures increase wildfire risk, and droughts weaken trees, so they are more likely to die.
How can mining damage forest ecosystems beyond the mine itself?
Toxic waste from mining damages ecosystems beyond the mining area.
Why are specialist species at risk from habitat loss?
Specialist species cannot adapt to the loss of their habitat, so they may become endangered.
How does deforestation cause soil erosion?
Without trees, roots no longer hold the soil, so rain washes the topsoil away.
Eroded soil washes into rivers and causes , which reduces river depth and increases the risk of flooding.
Eroded soil washes into rivers and causes silting, which reduces river depth and increases the risk of flooding.
How does deforestation contribute to global warming?
Cutting or burning trees releases carbon dioxide, and fewer trees remain to absorb carbon, which strengthens the enhanced greenhouse effect.
Why does rainfall decrease after deforestation?
Fewer trees release water vapour through transpiration, so fewer clouds form.
True or False?
Genetic depletion caused by deforestation reverses once the forest regrows.
False.
Genetic loss is permanent: once a species is gone, its traits cannot be recovered.
What is one social impact of deforestation?
One social impact is the loss of resources for indigenous forest communities; others include reduced food and clean water supplies and the loss of cultural sites.
True or False?
Deforestation brings long-term economic gains.
False.
Selling timber gives short-term income, but deforestation causes a long-term loss of valuable resources and reduces tourism potential.
Define sustainable management of forests.
Sustainable management of forests balances the needs of the environment, wildlife and humans while conserving forests for future generations.
What is the difference between reforestation and afforestation?
Reforestation replants trees where forest has been cut down, whereas afforestation plants new forests.
True or False?
A newly planted forest quickly matches the biodiversity of an old-growth forest.
False.
Young trees take many years to become a functioning forest, and single-species planting may lack biodiversity.
Define selective logging.
Selective logging is cutting only certain trees instead of clearing the whole forest.
How does selective logging let a forest recover?
Selective logging keeps most of the forest intact, which allows it to regrow between harvests.
Legal protection of forests works poorly in remote areas, where laws are difficult to .
Legal protection of forests works poorly in remote areas, where laws are difficult to enforce.
What do eco-labelling schemes such as the Forest Stewardship Council do?
Eco-labelling schemes label wood products that come from sustainably managed forests.
True or False?
Certified sustainable wood products always cost consumers less than uncertified ones.
False.
Certified wood products can be more expensive for consumers, which is a limitation of certification schemes.
Define agroforestry.
Agroforestry is the practice of growing crops and trees together.
What is one limitation of agroforestry?
Agroforestry may produce lower yields than large-scale monoculture farms.
How does community-based forest management protect forests?
Community-based management gives local people rights and responsibilities over forest land, so the people who depend on the forest protect it.
Why is income from ecotourism unreliable?
Ecotourism income may collapse if tourism demand falls.
Forests act as carbon because they absorb carbon dioxide during photosynthesis.
Forests act as carbon sinks because they absorb carbon dioxide during photosynthesis.
Define interception.
Interception is when raindrops land on leaves and branches instead of hitting the ground directly.
Why do rivers in forested areas fill more slowly after heavy rain?
More rain infiltrates the forest floor, so less water flows over the surface into rivers.
True or False?
Forests have no effect on rainfall in their region.
False.
Trees transpire, releasing water vapour that helps form clouds and rain.
Why are forests an important genetic resource?
Forests hold the genetic material for future crops, medicines and scientific research.
How do forests protect soil from erosion?
Tree roots bind the soil together, and plants on the forest floor protect it from heavy rain.
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