The feedback responses of belowground microbial communities to the interactive effects of global change factors remain poorly understood. Here we assessed the temporal turnovers of soil microbial communities as impacted by climate change factors, providing insight into the mechanisms shaping diversity and the corresponding changes to ecosystem functions and services. We examined the individual and interactive effects of climate warming, precipitation and land use change (e.g. clipping) on soil microbial communities in a long-term multifactor climate change experiment that includes air warming (ambient, +3°C), precipitation alteration (+100%, ambient and -50%), and plant clipping (unclipped and clipped) in the temperate grassland of Central Oklahoma (OK). Surface layer (0-15cm) soil samples from all plots were collected annually at the peak plant biomass season (Sep. or Oct.) from 2009 to 2014. To examine the successional dynamics of bacterial and fungal communities under multiple factors, a total of 264 soil samples were analyzed by sequencing of 16S rRNA gene and ITS amplicons and by functional gene array (GeoChip 5) analysis. Various statistical methods were used to detect the interactive effects of warming, precipitation alteration and clipping on the diversity, composition, structure, functional potential and dynamics of soil microbial communities with time.
Results/Conclusions
Experimental warming, clipping, and altered precipitation all significantly altered soil conditions at the sampling depth of 7.5 cm. Plant biomass significantly increased in clipped plots, but decreased in reduced precipitation plots. Dissimilarity analysis showed that each treatment alone and many of their interactions significantly affected the phylogenetic and functional structure of bacterial and fungal communities with time. Warming with any other treatments significantly increased temporal turnover rates of microbial communities, while clipping with increased precipitation significantly decreased temporal turnover rates of bacterial and fungal communities. Furthermore, altered communities under different turnover rates led to dramatic changes in functional potential of microbial communities with time. The abundance of many functional genes involved in C degradation, N cycling and P utilization was significantly increased by clipping and increased precipitation, but decreased by reduced precipitation and warming with clipping and reduced precipitation. Warming significantly increased species temporal turnover for bacteria and functional gene richness but not fungi and also enhanced the difference in community structures as time proceeded. These results indicated that with time warming had an increasingly predominant role in mediating microbial community structure in response to climate change factors, whereas clipping and moisture alternations became secondary.