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Harvard Forest Symposium Abstract 2017

  • Title: Soil warming increases biogeochemical silica mobilization and watershed export in a Northern hardwood forest
  • Primary Author: Jon Gewirtzman (Brown University)
  • Additional Authors: Joanna Carey (Boston University); Jim Tang (Marine Biological Laboratory)
  • Abstract:

    Silica, an essential nutrient for diatoms and a quasi-essential nutrient for many land plants. As such, it plays a role in terrestrial and marine primary productivity, and the biogeochemical cycles of silica and carbon are coupled. This study investigated effects of soil warming on the cycling of silica at Harvard Forest in order to predict future alterations to the silica cycle as climate change progresses. In the Barre Woods long-term soil warming plots, biogenic silica (BSi) concentrations were measured in 2015 canopy green leaf samples and leaf litter. We found BSi production was significantly elevated in the heated plot compared to the control plot. A litterbag decomposition experiment in 2016 found a higher rate of silica loss from leaf litter in the heated plot compared to the control plot. Although soil BSi stocks did not differ between the plots, dissolved silica (DSi) was significantly elevated in the heated plot soil water. Germanium, as a silicon tracer, was measured in soil water, leaf litter, and a nearby stream in order to determine potential sources and flowpaths of the elevated DSi. Preliminary analysis suggests that the elevated soil water DSi in the heated plot is at least partly biogenic in origin, and that stream DSi is supplied primarily by soil water. Collectively, these results indicate an increase in silica mobilization, plant uptake and release, and export from the forest as temperatures continue to increase with climate change.

  • Research Category: Watershed Ecology

  • Figures:
  • Soil Water and Stream DSi.png
    Canopy and Litter BSi.png
    Bulk Litter Mass Loss.png
    Soil BSi.png
    Soil Water Ge:Si.png