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Harvard Forest REU Symposium Abstract 2013

  • Title: The devil came down in the dirt: consequences of trophic interactions on carbon respiration and warming.
  • Author: Angus R Chen (Oberlin College)
  • Abstract:

    Soils occupy a pivotal position on the stage of terrestrial ecosystems, representing one of the largest fluxes of carbon after photosynthesis. As the threat of climate change rises, the question of carbon fluxes in the soil rise with it. Currently, most studies on soil respiration focus on total respiration of a soil ecosystem, but there has not yet been much inquiry on the isolated parts of soil ecosystems and their unique interactions. In order to do this, we independently examined two soil trophic groups, soil microbes and fungi, and invertebrates, by removing each one at a time through sterilization practices. When soil is sterilized and placed in an eastern deciduous forest, the soil experiences rapid re-colonization by sugar fungi. We were then able to study the interaction of these fungi and certain soil invertebrates by observing the soil chambers’ appearance and respiration. We imagined that the combination of fungi, microbes, and invertebrates would have the highest respiration, since this represents the greatest number and diversity of organisms. However, respiration by fungi and microbes appears higher in comparison to the respiration of recolonized soil with mealworms and earthworms, and both were higher than respiration in non-sterile soils. At the same time, there were considerable less visible fungi in soil chambers with invertebrates, while there were no visible fungi in non-sterile chambers. We observed invertebrate death after about two and a half weeks, resulting in the reversal of this trend. This suggests that fungal respiration is responsible for the majority of soil respiration in these chambers, and grazing of these organisms by invertebrates reduces total respiration. However, warming did not appear to have a strong impact on respiration, except in accelerating invertebrate death.

  • Research Category: Large Experiments and Permanent Plot Studies