Biology · BIODIVERSITY AND CONSERVATION

In David Tilman's long-term ecosystem experiments using outdoor plots, which of the following observations was confirmed regarding community stability?

1. Plots with more species showed greater year-to-year variation in total biomass.
2. Increased diversity contributed to higher productivity and less year-to-year variation in biomass.
3. Species richness had no measurable correlation with total biomass or disturbance resistance.
4. Higher species richness consistently caused lower primary productivity.