“Increased temperature disrupts biodiversity-ecosystem functioning relationships”

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Elodie C. Parain, Rudolf P. Rohr, Sarah M. Gray, and Louis-Félix Bersier (Feb 2019)

The DOI will be https://dx.doi.org/10.1086/701432

By increasing metabolism and ultimately competition, global warming disrupts the efficiency of ecosystem functioning

The biodiversity-ecosystem functioning experiment was conducted with protozoan species isolated from natural communities inhabiting the water-filled leaves of Sarracenia purpurea. The picture is of Champ-Buet field site, Switzerland.
(Credit: L.-F. Bersier)

The biodiversity-ecosystem functioning (BEF) relationship is a general pattern observed in many ecosystems in which processes such as nutrient cycling and food production are greatest when species diversity is highest. Many studies have examined this question under the present climatic conditions. However, little is known about how climate change will impact this relationship, and how the availability of ecosystem services will be affected. Using modelling and experiments, we show that a small increase in temperature can cause the BEF relationship to weaken or even vanish. Therefore, high diversity will no longer be a guarantee of a high ecosystem functioning. This is an important but overlooked argument to mitigate climate change.


Abstract

Gaining knowledge of how ecosystems provide essential services to humans is of primary importance, especially with the current threat of climate change. Yet, little is known about how increased temperature will impact the biodiversity-ecosystem functioning (BEF) relationship. We tackled this subject theoretically and experimentally. We developed a BEF theory based on mechanistic population dynamic models, which allows the inclusion of the effect of temperature. Using experimentally established relationships between attack rate and temperature, the model predicts that temperature increase will intensify competition and consequently the BEF relationship will flatten or even become negative. We conducted a laboratory experiment with natural microbial microcosms and the results were in agreement with the model predictions. The experimental results also revealed that an increase of both temperature average and variation had a more intense effect than an increase of temperature average alone. Our results indicate that, under climate change, high diversity may not guarantee high ecosystem functioning.