Importance of Biodiversity:-

• Acc. to David Tilman long term outdoor experiment observed that plot having more species diversity has less year to year variation in total biomass and also explain that plot having more species diversity contribute to in higher productivity and make ecosystem more stable.

Rivet poppet Hypothesis:-

Paul Ehrlich

Acc. to this hypothesis ecosystem behave as aeroplane and species behave as rivet. In aeroplane (ecosystem) all point joint together by 1000 of rivets (species). If all passenger travelling in aeroplane (ecosystem) start to remove rivet and carry it from aeroplane to home (extinction of species). Then initially there is no effect on fitness or safety of aeroplane. But when rivets are removed from wing  of aeroplane (exctinction of key stone species). Then it causes serious destruction of aeroplane (ecosystem) and finally aeroplane get crashed.

No direct effect but indirect effect is surely there explained by Paul Enrich.