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Natural grassland in the Auvergne mountains. © INRA, TOILLON Sylvie

Plant biodiversity and ecosystem vulnerability under climate extremes

Our environment is experiencing a number of changes, from biodiversity losses to global warming. INRA researchers were involved in a comprehensive European study that demonstrated that high plant species diversity does not always reduce ecosystem vulnerability under climate extremes. The findings were published on 28 November 2017 in the Journal of Ecology.

Updated on 01/11/2018
Published on 12/01/2017

Ecosystem, species and genetic diversity are all declining as the number of climate change-driven extreme weather events rises around the world. Recent studies, which focus on moderate weather fluctuations, show that higher biodiversity improves ecosystem stability. However, very little research exists on the impact of extreme events. INRA researchers teamed up with other colleagues to conduct a broad literature review to examine the interactions between biodiversity and extreme events and determine whether plant diversity can mitigate the effects of severe droughts, heatwaves or periods of heavy rainfall.

Contrary to expectations, greater plant species diversity does not always safeguard herbaceous ecosystem functioning during extreme events (drought or rainfall). The researchers have several possible theories for these findings.

The mechanisms that may help strengthen ecosystem resistance, such as compensation by better adapted species (which take over the functional role of other species), appear to be inadequate against extreme events. Neutral or even negative biodiversity effects under extreme events could be explained by changes in biotic interactions (plant-plant, plant-soil) within the ecosystem. There could also be divergences between responses from in natura communities and the in artificial communities used in many experiments. Compared to artificial plant communities, in natura ecosystems are home to fewer plant species, which are most often derived from communities that were initially more diverse but subject to anthropic selection pressures (intensified practices, eutrophication). The result is a community of fast-growing species that do well in optimal conditions but are less resilient in poor climate conditions (e.g., drought). Reducing eutrophication could improve the diversity of species with different growth rates and create ecosystems with stronger resistance to extreme events.
 
This comprehensive review takes a novel look at the relationship between species richness and extreme events and suggests that the functional role of diversity (variety and variance of plant traits) may be more important than simply species numbers. Moreover, it provides direction for future research on the impacts of climate change on ecosystems, underlining that higher plant species diversity alone cannot improve ecosystem resistance to climate extremes.

Contact(s)
Scientific contact(s):

Press Relations:
INRA News Office (33 (0)1 42 75 91 86)
Associated Division(s):
Forest, Grassland and Freshwater Ecology
Associated Centre(s):
Auvergne Rhône-Alpes

Reference

De Boeck HJ, Bloor JMG, Kreyling J, et al. Patterns and drivers of biodiversity–stability relationships under climate extremes. J. Ecol. 2017;00:1–13. DOI: 10.1111/1365-2745.12897