David Tilman’s long-term ecosystem experiments using outdoor plots suggested that

David Tilman conducted long-term ecosystem experiments using outdoor plots. He found that plots with more species showed less year-to-year variation in total biomass. He also found that increased diversity contributed to higher productivity. Communities with more species would be more stable and are more resistant to occasional disturbances. Paul Ehrlich’s Rivet Popper Hypothesis suggests that loss of key species poses a major threat to the ecosystem.