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Harvard Forest REU Symposium Abstract 2014

  • Title: Spiders, Springtails, and Soil Respiration: Top-down Effects within the Soil Food Web
  • Author: Heather R Clendenin (Bowling Green State University)
  • Abstract:

    The respiration of soil microbes releases ten times the amount of CO2 as anthropogenic inputs. Changes in the activity and biomass of soil microbes, which both affect respiration, can be linked to the presence and density of springtails (arthropods in the subclass Collembola). Additionally, predation by spiders alters the density and activity of Collembola, and may subsequently affect soil respiration. This study addresses the top-down control wolf spiders (genus Pardosa) may have upon soil respiration through their interactions with Collembola. It aims to differentiate between changes caused by predation and those caused by trait-mediated interactions, specifically behavioral changes due to predator presence. In step with other studies examining predators’ net effects, we hypothesized that trait-mediated interactions would be of the same magnitude as the lethal effects of predation. To examine this, we set up mesocosms with three treatment types: Collembola present and spiders absent; Collembola present with spiders modified to prevent predation; Collembola present with unmodified spiders. Soil efflux was recorded over a 5 week period using LiCor 6400, and analyzed using a one-way ANOVA in R. We expected efflux rates to vary significantly between the control and both treatments with predators present, indicating that trait-mediated interactions are as significant as the lethal effects of predation. Examining the role of predators in the soil ecosystem should shed light on top-down effects upon soil respiration. As issues associated with global climate change are addressed, carbon efflux in the soil ecosystem, including the role played by invertebrates, should bear consideration.

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