4.2 EVALUATING BIODIVERSITY AND VULNERABILITY Revision notes
1. Identify factors that lead to loss of biodiversity (9)
2. Discuss the perceived vulnerability of tropical rainforests and their relative value in contributing to global
Why so diverse? So many layers, habitats, niches and therefore species
Vulnerable/fragile because species there have such a specific habitat that they would find it hard to survive anywhere
else. All adapted to this environment e.g. lianas,
All nutrients in vegetation. Space wanted for other things as in LEDCs. Once cleared can’t regrow, especially if large area
Causes of destruction:
Effects of destruction:
Soil Air Water Species
3. Discuss current estimates of numbers of species and past and present rates of species extinction
Mass extinction every 100 million years.
CT: 65M ya End T PT Late D OS Modern
18% land verts,
Hard to estimate some spp because: speciation, extinction, v small – insects down to microscopic, difficult locations.
Used to be 1 mammal spp extinct every 200 yrs, now 45 x predicted rate.
4. Describe and explain the factors that may make species more or less prone to extinction
1. Large mammals – source of food, easy to spot, need space and food, top of food chain.
5. Outline the factors used to determine a species’ Red List conservation status. (7)
1. Population size
6. Describe the case histories of three different species: extinct, critically endangered and status improved by
Ext.: Crit.: Impr:
7. Describe the case history of a natural area of biological significance that is threatened by human activities