Proximate Causes of Biodiversity Loss

Proximate Causes of Biodiversity Loss

1. Habitat destruction

2. Overexploitation

3. Invasive species

4. Pollution

5. Climate change

Habitat Destruction

•Habitat destruction as a result of human activities including urbanization, agricultural expansion and logging leave animals and plants without a suitable place to live

•More than 85% of threatened birds, mammals and amphibian are affected by habitat destruction

•Deforestation rate positively correlates with human population growth rate in many parts of the world

• Deforestation is a serious threat to Sumatran Tiger• Each year between 2000 to 2005, 10.4 millions hectares of

tropical forest were destroyed

Overexploitation

•Overexploitation is the harvest of plants and animals at a rate which is higher than their natural reproduction rate

•Overexploitation for food, recreation, construction and medicine has lead to population fall and extinction

• Overhunting for food resulted in extinction of Dodo in Mauritius

• Hunting of Asian Pangolin for medicinal uses has caused decline in population size

Invasive Species

• Invasive species is introduced intentionally or accidently outside their normal range and harmful to

native species

• Invasive species threaten biodiversity by spreading diseases, acting as predator or parasite, competing

or hybridizing with native species and altering habitat

• The shrub Clidemia hirta threatens endemic plants in Hawaii• Nile Perch has led to extinction of Cichlid fish in Lake Victoria

Pollution

•Pollution is the release of contaminants and toxic substance to the environment

•Water, air and soil – the three main natural resources could be affected by pollution

•Pollution disrupt chemical cycle in the biosphere such as nitrogen and carbon cycle

• The Osprey were negatively affected by the chemical DDT in the 1960s

• Organic waste and leaching of fertilizer may lead to eutrophication of lakes

Climate Change

•Climate change alter the distribution of ecosystems, biomes and suitable habitat

•Climate change require animals and plants to adapt ecologically, behaviorally and physically – but

some may not be able to adapt accordingly

•15 to 37% of 1,103 animals and plants sampled are predicted to become extinct by 2050 because of climate change

• Increase in sea temperature has reduced coral reefs cover because of coral bleaching

• Mismatch of migratory bird behavior with changes in the environment