Soil biotic processes remain remarkably stable after 100-year extreme weather events in experimental grassland and heath
Climate change will increase the recurrence of extreme weather events such as drought and heavy rainfall. Evidence suggests that extreme weather events pose threats to ecosystem functioning, particularly to nutrient cycling and biomass production. These ecosystem functions depend strongly on below-ground biotic processes, including the activity and interactions among plants, soil fauna, and micro-organisms. Here, experimental grassland and heath communities of three phytodiversity levels were exposed either to a simulated single drought or to a heavy rainfall event. Both weather manipulations were repeated for two consecutive years. The magnitude of manipulations imitated the local 100-year extreme weather event. Heavy rainfall events increased below-ground plant biomass and stimulated soil enzyme activities as well as decomposition rates for both plant communities. In contrast, extreme drought did not reduce below-ground plant biomass and root length, soil enzyme activities, and cellulose decomposition rate. The low responsiveness of the measured ecosystem properties in face of the applied weather manipulations rendered the detection of significant interactions between weather events and phytodiversity impossible. Our data indicate on the one hand the close interaction between below ground plant parameters and microbial turnover processes in soil; on the other hand it shows that the plant–soil system can buffer against extreme drought events, at last for the period of investigation.
KeywordsClimate change Decomposition Drought Functional diversity Minirhizotron Precipitation Root length Soil enzyme activity
We thank Anna Miller, Hanna Skiba, Lukas Müller and several other student workers for their help in field work and digital image analysis as well as Gudrun Hufnagel for soil enzyme activity measurements. We are also very thankful to two unknown reviewers for their valuable comments.
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