On biodiversity mechanisms and a biodiversity crisis

Thu, Nov 21, 2019, 12:30 pm

How species richness is maintained in ecological communities keeps both theoretical and empirical ecologists fascinated. Important recent topics are how theory can be made more relevant to real-world ecosystems and how empirical observations can properly test theoretical predictions. We have shown that most of the common tests of modern coexistence theory can demonstrate that species interactions are stabilized but not that species stably coexist. Moreover, theory applies to low diversity communities only, while current challenges are with maintaining high-diversity ecosystems.

Threats to ecological communities are manifold and some effects are new. Our analysis of long-term data from German nature reserves demonstrated that they have lost three-quarters of their insect biomass over the last 30 years. Such impoverishment can only occur if also the more common species are reduced in abundance and number of species, as confirmed by further analyses of the hoverfly communities. Such trends in the common species seem at odds with the extinction vortex, describing the interplay between biotic and abiotic factors causing species extinction.

The causes of the insect decline are now heavily debated in the literature and in the public domain, and plans are developed for restoring our landscape to invigorate these communities. What can ecological theory contribute to elucidating the causal mechanisms of the decline, and estimating the chances of success of reverting the negative trends?

Guyot 10
Open to public.

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