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1. Studying the effects of extreme climatic or weather events such as drought and heat waves on biodiversity and ecosystem functions is one of themost important facets of climate change research. In particular, primary production is amounting to the common currency in field experiments worldwide. Rarely, however, are multiple ecosystem functions measured in a single study in order to address general patterns across different categories of responses and to analyse effects of climate extremes on various ecosystemfunctions.2. We set up a long-term field experiment, where we applied recurrent severe drought events annually for five consecutive years to constructed grassland communities in central Europe. The 32 response parameters studied were closely related to ecosystem functions such as primary production, nutrient cycling, carbon fixation, water regulation and community stability. 3. Surprisingly, in the face of severe drought, above- and below-ground primary production of plants remained stable across all years of the drought manipulation.4. Yet, severe drought significantly reduced below-ground performance of microbes in soil indicated by reduced soil respiration, microbial biomass and cellulose decomposition rates as well as mycorrhization rates. Furthermore, drought reduced leaf water potential, leaf gas exchange and leaf protein content, while increasing maximum uptake capacity, leaf carbon isotope signature and leaf carbohydrate content. With regard to community stability, drought induced complementary plant-plant interactions and shifts in flower phenology, and decreased invasibility of plant communities and primary consumer abundance.5. Synthesis. Our results provide the first field-based experimental evidence that climate extremes initiate plant physiological processes, whichmay serve to regulate ecosystemproductivity. A potential reason for different dynamics in various ecosystem services facing extreme climatic events may lie in the temporal hierarchy of

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.

Secondary habitats, like open cast mines, represent ideal cases for the study of colonization process in the course of ongoing succession. We used molecular methods to study the population structure of the earwig Labidura riparia (Pallas 1772, Dermaptera) in the post-mining landscape in Lower Lusatia. Genetic diversity of highly polymorphic microsatellite markers was analysed in earwig populations of disturbed secondary habitats, i.e. post-mining landscapes (PML) and former military training areas (MTA) and of primary habitats from coastal and inland sand dunes. The earwig is a rare habitat specialist and inhabits sandy but damp sites free of vegetation or with sparse vegetation. First, observations of L. riparia in Lusatia were made in the middle of last century in secondary habitats like open cast mines or sand and gravel pits. Out of 21 investigated populations those from secondary habitats have higher number of alleles and higher gene diversity than populations from primary habitats. Genetic depletion at secondary habitats due to bottlenecks was not evident. Age of sampling site and type of succession (PML sites with primary succession, MTA with secondary succession) had no impact on gene diversity. A correlation between geographic distance and genetic distances indicates that ongoing gene flow counterbalances genetic drift:. The two primary habitats, coastal and inland dunes were significantly different indicating strong isolation among these spatially distant habitats. Some alleles were missing in coastal populations which may be due to demographic bottlenecks. Secondary habitats (PML, MT A) were more closely related to inland dune than to the coastal populations which suggests that earwigs which colonised Lusatia did not come from coastal populations but probably from an inland dune (Klein Schmölen) near river Elbe. The results suggest that Labidura riparia individuals can overcome larger distances, possibly by flying. Due to their large population size and h