"Stability of a community depends on its species richness." Write how did David Tilman show this experimentally.

Explanation

Ecologists believe that communities with more species tend to be more stable than those with less species. This was confirmed by David Tilman.
David Tilman showed this experimented by:
i) Productivity should not vary to much from year to year.
ii) It should be resistent to occasional natural and man-made disturbances.
iii) It should be resistant to invasions by alien species.