%0 Journal Article %A A. Salazar %A J.T. Lennon %A J.S Dukes %T Microbial dormancy improves predictability of soil respiration at the seasonal time scale %D 2018 %R 10.1101/434654 %J bioRxiv %P 434654 %X Climate change is accelerating global soil respiration, which could in turn accelerate climate change. The biological mechanisms through which soil carbon (C) responds to climate are not well understood, limiting our ability to predict future global soil respiration rates. As part of a climate manipulation experiment, we tested whether differences in soil heterotrophic respiration driven by season or climate treatment (RH) are linked to 1) relative abundances of microbes in active and dormant metabolic states, 2) net changes in microbial biomass and/or 3) changes in the relative abundances of microbial groups with different C-use strategies. We used a flow-cytometric single-cell metabolic assay to quantify the abundance of active and dormant microbes, and the phospholipid fatty acid (PLFA) method to determine microbial biomass and ratios of fungi:bacteria and Gram-positive:Gram-negative bacteria. RH did not respond to climate treatments but was greater in the warm and dry summer than in the cool and less-dry fall. These dynamics were better explained when microbial data were taken into account compared to when only physical data (temperature and moisture) were used. Overall, our results suggest that RH responses to temperature are stronger when soil contains more active microbes, and that seasonal patterns of RH can be better explained by shifts in microbial activity than by shifts in the relative abundances of fungi and Gram-positive and Gram-negative bacteria. These findings contribute to our understanding of how and under which conditions microbes influence soil C responses to climate.We gratefully acknowledge the help of Clara Vasquez and Risa McNellis with the fieldwork at BACE, the help of Elizabeth Morgan Davis and Nishit Banka with the PLFA analyses, and the help of Christiane Hassel with the flow cytometry analyses. We further acknowledge the many technicians and assistants who constructed and maintained the BACE. AS acknowledges COLCIENCIAS (Departamento Administrativo de Ciencia Tecnología e Innovación en Colombia) and the Fulbright-Colombia program. In addition, this work was supported in part by National Science Foundation Dimensions of Biodiversity Grant 1442246 (JTL) and US Army Research Office Grant W911NF-14-1-0411 (JTL). Work at the BACE was made possible by funding from the United States Department of Agriculture (USDA; 2015-67003-23485; JSD). The BACE was built and maintained with funding from the National Science Foundation (DEB-0546670 and DEB-1146279) and the US Department of Energy’s Office of Science (BER), through the Northeastern Regional Center of the National Institute for Climatic Change Research, and the Terrestrial Ecosystem Science program. We thank the University of Massachusetts and UMass Extension for leasing land to the BACE. Partial support for JSD’s participation in this project was provided by Hatch project 1000026 of the USDA’s National Institute of Food and Agriculture. This is paper no. 1801 of the Purdue Climate Change Research Center (PCCRC). We declare no conflict of interest. %U https://www.biorxiv.org/content/biorxiv/early/2018/10/03/434654.full.pdf