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Harvard Forest Symposium Abstract 2020

  • Title: Drivers and mechanisms of long-term soil response to chronic warming
  • Primary Author: Luiz Domeignoz Horta (University of Massachusetts - Amherst )
  • Additional Authors: Kristen DeAngelis (University of Massachusetts - Amherst ); Serita Frey (University of New Hampshire - Main Campus); Jerry Melillo (); Grace Pold (University of Massachusetts - Amherst )
  • Abstract:

    The predictions of how soil carbon stocks change with chronic warming are highly sensitive to the assumptions made about microbial parameters such as carbon use efficiency (CUE). CUE is the fraction of carbon (C) taken up by microbial cells and retained in biomass in relation to the fraction lost via respiration. CUE partitions the flow of C to the atmosphere, decomposer communities and potential soil C stocks. Because microbes regulate soil C cycling, more efforts are needed to understand drivers of long- and short-term responses of CUE to better predict soil carbon stocks in a warming world. In this ongoing work, we sampled soils from two long-term experimental sites that have been heated for 28 or 13 years in a mid-latitude hardwood forest at the Harvard Forest Long-term Ecological Research (LTER) site. We collected organic and mineral soils in summer and fall and measured the response of carbon use efficiency and extracellular enzyme activity to temperature (4C to 30C). Respiration, a CUE component, and extracellular enzyme activity both showed a smaller response to increasing temperature in heated compared to control soils. In the next steps of this work we will measure carbon quality. Our working hypothesis is that substrate quality plays a role in the adaptation of CUE to long-term warming. We expect to find depletion in the more labile soil carbon pool in heated compare to control soils which could result in smaller CUE in these soils. This work will elucidate the effect of long-term warming to soil carbon pools and to microbial CUE response to temperature helping us better predict possible feedback mechanisms between soil and the atmosphere.

  • Research Category: Soil Carbon and Nitrogen Dynamics, Physiological Ecology, Population Dynamics, and Species Interactions, Biodiversity Studies