The biological wealth of our planet has been declining rapidly which leads to loss of biodiversity. The loss of biodiversity in a region may lead to many effects, such as–

(a) Decline in plant production, 

(b) Lowered resistance to environmental perturbations, and 

(c) Increased variability in certain ecosystem processes. 

Causes of biodiversity losses are:– 

(1) Habitat distruction and fragmentation – Due to intense antitropogenic activities the number of temperate rain forests are greatly minimized. As a result enumerable species living or in are being extinct. Due to increased pollution load, the biotic habitat is being fragmented as a result many species are extinct. 

(2) Over exploitation – Human beings has over exploited the natural resources for their need and greed, as a result many species of commercial importance are either become extinct or are on the verge of extinction. 

(3) Invasion of exotic species – The inclusion of exotic species in any ecosystem either knowingly or unknowingly has greatly affected the existence of local species. The invasion of exotic species is one of the principal cause of their distruction. 

(4) Co-extinction – when one species becomes extinct the species of plants and animals associated with it also become extinct. Like the extinction of a plant having mutual relationship with an insect, leads to extinction of the insect also.