Soil biodiversity and the stability of mutiple ecosystem functions

Background/Question/Methods

Soil microbes, although for the most part unseen, represent the largest portion of life on this planet and are crucial for the functioning of terrestrial ecosystems. But, soil community composition is dependent on soil history and may consequently alter the sensitivity of soil communities to biodiversity loss. Increased biodiversity supports ecosystem functioning as different organisms perform dissimilarly when abiotic conditions fluctuate over space and time. However, the ability of diverse soil communities to maintain multiple ecosystem functions in the face of a changing climate is not well known. We focused on understanding the link between soil community composition and diversity as a mechanism for stabilizing multiple ecosystem functions. To do this, soil was collected from three sites with varying soil histories. Within each we created a soil community diversity gradient based on species body size. Multiple ecosystem functions were traced over a one-year period for each soil community planted with a standard grassland plant community in self-contained microcosms. A reduced water regime was applied at regular intervals as a fluctuating environmental condition so that the stability in overall ecosystem performance could be assessed in relation to soil community composition and soil biodiversity loss.

Results/Conclusions

Overall, greater soil biodiversity was found to improve plant productivity and diversity, decomposition of organic matter, C sequestration, and N turnover between above and belowground systems.  Moreover, greater soil biodiversity improved the stability of many of these ecosystem functions. Our results are the first to link biodiversity stability theory in belowground communities with aboveground ecosystem stability. Understanding this relationship is a field of study that will become increasingly relevant, as variability in environmental conditions is predicted to increase around the globe.