Seasonal effects stronger than three-Year climate Manipulation on Grassland soil Microbial community

climate change will interact with seasonal variation in precipitation and temperature to alter plant and soil microbial relationships and the ecosystem services provided. we currently lack critical information on how grassland soil microbial dynamics will be altered by climate change, and the seasonal dependency of microbial responses. we measured soil microbial biomass, community composition, enzyme activities, potential c mineralization, and catabolic responses to nine substrates seasonally in a north american pasture subjected to 3 yr of warming (+3°c) and elevated growing season precipitation (+30% of the mean annual total). we hypothesized that climate treatments would elicit seasonally dependent changes in the microbial community (e.g., warming may increase microbial biomass and activity during cooler, wetter winter months compared with reductions in hotter, drier summer months). we observed significant seasonal effects for all measured soil microbial parameters, but few treatment effects. winter soils from warmed plots contained less potentially mineralizable c than plots with ambient temperatures or warming with added precipitation. warmed treatments contained 16% higher microbial biomass c, on average, than ambient temperature plots. Year-round microbial respiratory responses to sucrose and cellulose additions were also 34 and 22% greater, respectively, in warmed plots. we observed no effect of climate treatments on microbial lipid biomass, community structure, extracellular enzyme activities, or catabolic response to seven substrates. despite climate treatments significantly altering plant community composition and environmental conditions in season-dependent ways, we measured few interactive effects, suggesting soil microbes at this site may maintain similar functioning under future warmer, wetter conditions.