University of Michigan Biological Station: Climate change- and disturbance- driven forest transitions: Their impacts on forest floor processes.
Our objective in this work is to elucidate processes related to C emissions from the forest floor by quantifying the relationship between C emissions, microclimate, vegetation cover and litterfall, and litter-dwelling biota across: i) a 100 yr old burn chronosequence, ii) a pre-existing accelerated forest succession experiment spanning more than 30 hectares, and iii) a new field manipulation of the intensity and timing of climatic warming. Our central hypothesis is that C emissions will be highest under intermediate disturbance and warming conditions because diversity and abundance of organisms comprising the litter food web will be highest. We will compare our estimates of C flux with estimates from an onsite US DOE supported AmeriFlux tower and pair our efforts aimed at capturing C flux from the forest floor with those of investigators working on complementary questions at the forest canopy.
Harvard Forest: Soil invertebrate engineers and predators: Their contributions to carbon-climate change feedback loops.
Our objective in this project is to determine the contributions of soil invertebrate predators and engineers to soil C emissions under different warming scenarios. Our central hypothesis is that invertebrate responses to warming generate a positive feedback on climate change by increasing C emissions under warming. We will use an iterative process coupling bioenergetic food web modeling with field based invertebrate-warming manipulations. Our expectation is that soil C emissions increase under warming in the presence of invertebrate predators and engineers because temperature-induced increases in these invertebrate activities affect microbial communities and thus C emissions.
We are working with Creighton Litton (University of Hawaii) to determine how insect diversity varies across an elevational gradient spanning 5°C on the Big Island. We will determine how temperature, litter-dwelling insects and C are related to each other in a tropical, yet nutrient limited, system. Additionally, we will pursue questions related to global change and insects at the aquatic-terrestrial interface. For example, we will ask how climate-induced changes in phenology (e.g., timing of spring emergence) affect the movement of insects (e.g., dragonflies, mayflies) with aquatic life stages to terrestrial systems in the Great Lakes region. With these movements of these insects between these systems come translocation of C and other limiting nutrients.