Meeting Abstract
Identifying factors that control soil CO2 emissions will improve our ability to predict the magnitude of climate change soil ecosystem feedbacks. Despite the integral role of invertebrates in soil systems, they are excluded from climate change models. Soil invertebrates have consumptive and non-consumptive effects on microbes, whose respiration accounts for nearly half of soil CO2 emissions. By altering the behavior and abundance of invertebrates, predators may have indirect effects on microbial soil respiration. We examined the effects of a generalist predator on soil respiration under warming. Based on research suggesting invertebrates may mediate soil CO2 emission responses to warming, we predicted that predator presence would result in increased emissions by negatively affecting these invertebrates. We altered the presence of wolf spiders (Pardosa spp.) in mesocosms containing a community of soil invertebrates. To simulate warming, we placed mesocosms of each treatment in 10 open-top warming chambers ranging from 1.5-5.5° C above ambient at Harvard Forest, MA. As expected, CO2 emissions increased under warming and we found an interactive effect of predator presence and warming, though the effect was not consistent through time. The interaction between predator presence and warming was the inverse of our predictions: mesocosms with predators had lower respiration under warming than those without predators. CO2 emissions were not significantly associated with microbial biomass. We did not find evidence of consumptive effects of predators on the invertebrate community, suggesting that predator presence mediated response of microbial respiration to warming through non-consumptive means. We found a significant interaction between warming and predator presence that warrants further research into mechanism and generality of this pattern to other systems.
