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Harvard Forest Symposium Abstract 2014

  • Title: DIRT beyond the Harvard Forest: Litter Input Controls on Soil Carbon in a Temperate Deciduous Forest in Pennsylvania
  • Primary Author: Richard Bowden (Allegheny College)
  • Additional Authors: Lauren Deem (University of Hawaii, Honolulu); Kate Lajtha (Oregon State University); Knute Nadelhoffer (University of Michigan (all campuses)); Clemente Peltre (University of Copenhagen); Alain Plante (The University of Pennsylvania)
  • Abstract:

    To examine the regional applicability of the Detritus Input and Removal Treatment (DIRT) experiment at the Harvard Forest, above- and belowground litter inputs in a temperate deciduous in Pennsylvania forest were altered for 20 years to determine the importance of leaves and roots on soil carbon (C) and organic matter (SOM) quantity and quality. C and SOM quantity and quality were measured in O horizon and mineral soil to 50cm in five treatments (Control, Double Litter (DL), No Litter (NL), No Roots (NR), No Inputs (NI)). After two decades of doubled litter addition, soil C and SOM did not increase (Bowden Figure 1). However, leaf litter exclusions reduced soil C (O and mineral horizons combined) by 24% in NL and 33% in NI. NR treatments showed no losses of C. Thermal characterization of SOM quality differed among treatments in the 0-10 cm depth. Patterns of CO2 evolution during SOM combustion revealed differences in SOM quality between surface and deeper horizons (Bowden Figure 2). Our work shows that the sources of litter are important in controlling soil C. Leaf litter made important contributions to maintaining current stocks of soil C; increased leaf litter did not increase soil C, but decreases in litter inputs resulted in rapid soil C declines. Root litter may ultimately provide more stable sources of soil C. Management activities or environmental alterations that decrease litter inputs in mature forests can lower soil C content, however increases in forest productivity and the resulting increased litter production seem unlikely to increase soil C sequestration.

  • Research Category: Large Experiments and Permanent Plot Studies, Regional Studies, Soil Carbon and Nitrogen Dynamics

  • Figures:
  • Bowden 2014 Fig 1.pdf
    Bowden 2014 Fig 2.pdf