Is diversity a buffer against environmental temperature fluctuations? - A decomposition experiment with aquatic fungi

We tested if species-rich fungal assemblages are functionally more efficient in leaf decomposition under environmental fluctuations than species-poor assemblages. We manipulated temperature fluctuations in laboratory microcosms in which oak leaf discs were inoculated with monocultures of aquatic hyphomycetes or random mixtures of three or eight species and subjected to different temperature regimes, including three constant temperatures and temperature fluctuation regimes. Temperature regime and identity of fungal species inoculated in monoculture microcosms significantly affected decomposition rates: these increased with temperature, but across all temperature regimes species diversity promoted higher decomposition rate, although functional saturation seemed to occur above three species. In assemblages with at least eight species, litter decomposition was not inhibited by temperature fluctuating regime when compared with constant temperature conditions. Ecosystem function under environmental changes seems to benefit from the presence of multiple species.