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Harvard Forest REU Symposium Abstract 2015

  • Title: The effects of soil warming on relative phosphorus availability and mycorrhizal communities
  • Author: ()
  • Abstract:

    Soil warming, as an effect of climate change, has the potential to alter soil processes, nutrient availability, and soil community composition. The Barre Woods Soil Warming Experiment was designed to monitor these effects, and in the first decade of the experiment, nitrogen availability increased, leading to accelerated aboveground tree growth. However, in the past two years, woody increment has returned to control rates and phosphorus resorption in leaf tissue has increased, leading us to hypothesize that chronic soil warming has led to progressive phosphorus limitation. We developed two hypotheses that could explain phosphorus limitation – reduced phosphate bioavailability or shifts in mycorrhizal exploration types. We used ion exchange membranes to assess the effect of soil warming on phosphate availability, and found that there were no significant differences between treatments. However, by characterizing 59 ectomycorrhizal morphotypes, we found that there was a significant shift to contact exploration species in the heated plot over both short and long-distance. This indicates that trees in the heated plot might not have as much access to phosphate because they aren’t connected to a large hyphal network. Alternatively, the shift in mycorrhizal species could change the enzymes produced in the soil, which would affect the breakdown of organic matter and nutrient availability. We tested the potential enzyme activity of phosphatase – an enzyme produced by fungi to make phosphate ions available – but found that there was no significant difference between treatments.

  • Research Category: Group Projects

  • Figures:
  • Phosphate Data.jpg
    Exploration Strategies.jpg