Predator contributions to above- and below-ground responses to warming

Identifying the factors that control soil carbon dioxide emissions will improve our ability to predict the magnitude of climate change-soil ecosystem feedbacks. Despite the integral role that invertebrates play in belowground systems, they are excluded from Earth System Models used to generate climate change predictions. While microbe and plant root respiration account for the majority of soil CO₂ emissions, soil invertebrates do have strong effects on microbes and plants. These effects are driven not only by invertebrate consumption of roots and microbes, but also by changes in soil structure and resource availability caused by invertebrate decomposition and ecosystem engineering. By altering the behavior and abundance of invertebrates that directly interact with the microbes and plant roots, generalist predators likely have a strong, indirect effect on soil respiration. We examined the effect that a generalist arthropod predator has on above- and belowground respiration and how this relationship changes under different warming scenarios. We built mesocosms with red maple (Acer Rubrum) saplings and soil invertebrates (e.g. detritivores, microbivores, belowground herbivores) and altered the presence of predators. To simulate warming, we placed a mesocosm of each treatment in ten open-top warming chambers at Harvard Forest,  MA that range from 1.5-5.5°C above ambient. We collected respiration data, microbial abundance, soil moisture, soil temperature, plant biomass, and invertebrate burrowing depths to determine the effect of predators on above- and belowground systems. We found that both warming and the predator affected soil respiration, decomposition, and microbial biomass. These effects were strongest in the warmest treatment.