The three major causes of biodiversity loss are :

 

(i) Habitat loss and fragmentation - Over- population, urbanisation and industrialisation require additional land every year. It can come through destruction or fragmentation of natural habitats through filling wetlands, ploughing grasslands, cutting down trees, burning a forest and clearing some area of vegetation. Loss of habitat results in annihilation of species of endemic plants, microorganisms and forcing out of animals which in alien lands die out after some time. Migrating animals would go astray and get killed.

 

(ii) Over-exploitation – Excessive exploitation of a species, whether a plant or an animal, reduces size of its population so, that it becomes vulnerable to extinction. Due to over-exploitation by humans, Dodo, three subspecies of tiger and Steller’s sea cow have become extinct in the last 500 years.

Alien species invasions – Non-native or alien species are often introduced by man for their economic and other uses. They often become invasive and drive away the local species. For example, water hyacinth (Eichhornia crassipes) was introduced in Indian waters due to its aesthetic value but turned out to be a problematic species. It clogged water bodies including wetlands at many places resulting in death of several aquatic plants and animals