Presented by Dr. Forest Isbell, University of Minnesota, at the Ecological Society of America Meeting (online) in 2020, as part of the LTER at 40 symposium.

Background/Question/Methods
Over the past quarter century, long-term ecological research has found that biodiversity is not only responding to global environmental changes, it is also an important regulator of ecosystem processes. Furthermore, many of nature’s contributions to people directly depend on biodiversity. Early observational studies and agricultural intercropping experiments were limited by an inability to disentangle effects of species identity from those of species diversity. Since the mid-1990s, dozens of theoretical studies and hundreds of modern biodiversity experiments successfully isolated identity and diversity effects in a wide range of terrestrial, marine, and freshwater ecosystems. More recently, observational studies have been conducted in naturally-assembled ecosystems worldwide. New studies are now considering the larger spatial and temporal scales that are most relevant for biodiversity conservation and policy.

Results/Conclusions

In this talk, I highlight insights from LTER studies considering how ecosystem processes depend on effects of species identity and species diversity, including its richness and evenness/dominance components. Both identity and diversity effects are often substantial in magnitude, and can reinforce or counter-balance one another. The loss of species richness consistently and substantially decreases primary production, ecosystem stability, and resistance to extreme weather events. It remains unclear, however, whether global environmental changes are altering ecosystems by systematically favoring certain types of species, such as those that are most (or least) productive or stable. Even if communities are not becoming increasingly dominated by these biased subsets of species, species identity can substantially alter ecosystem functioning and stability through spatial and temporal beta diversity.

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