OPUS: CRS, Soil Biogeochemical Responses to Interacting Global Change Drivers and Feedbacks to the Climate System

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Synthesis of long-term ecological datasets is important for providing new scientific insights and advances. The aim of this project is to conduct a research synthesis of data collected over nearly two decades from several long-term global change experiments. The overarching goal is to understand the soil responses to three global changes of significance for ecosystems in the northeastern United States (climate warming, atmospheric nitrogen deposition, and invasion by non-native plants). Soils are the largest repository of carbon (as organic matter) in the terrestrial biosphere, and the degree to which these global changes will accelerate or suppress soil organic matter decay will influence carbon and nutrient cycling processes and feedbacks to the climate system. The results and products of this research will provide a synthetic understanding of how soil warming, soil nitrogen enrichment, and plant invasion interact to influence biological and chemical processes in forest soils.The aim of this OPUS project is to conduct a core research synthesis of data collected over 18 years from four long-term global change experiments at the Harvard Forest Long-term Ecological Research site with the goal to understand how multiple global change drivers act individually and in combination to influence soil microbial and biogeochemical parameters, with an emphasis on fungal community and soil organic matter dynamics. The ongoing experiments span 14-32 years in duration and represent some of the longest running experimental manipulations of their type globally. These sites have the same climate and similar soils, vegetation, and land-use histories and use identical soil warming and nitrogen fertilization techniques. A coordinated set of biogeochemical and microbial measurements have been made. This data synthesis approach offers a unique opportunity to understand how increasing soil temperatures, soil nitrogen enrichment, and biotic invasion individually or in combination affect soil biogeochemistry, plant-soil interactions, and microbial community dynamics over time. While several syntheses have been done for individual experiments, there has been no coordinated effort to integrate and synthesize data across experiments. The synthesis plan has two key components: (1) testing a mechanism for the soil carbon response to simultaneous warming and nitrogen enrichment, and (2) a cross-study synthesis of fungal community responses to global change and linkages to soil carbon storage. Data sets to be used in this synthesis include long-term records of 1) soil abiotic parameters (temperature, moisture, pH, bulk density, texture); 2) biogeochemical measurements (soil respiration, inorganic N, N mineralization, total soil C and N, root biomass, mycorrhizal colonization); and 3) microbial biomass, activity, diversity, community composition, and functional capacity. The project will provide training for postdoctoral researchers and study results will be incorporated into classes taught at the University of New Hampshire.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.