Testing Mechanisms of How Mycorrhizal Associations Affect Forest Soils
Mycorrhizae are a type of fungi that form a symbiosis with plant roots whereby they receive organic carbon from photosynthesis in return for providing the plant with essential nutrients like nitrogen. There are two main types of mycorrhizae that associate with trees in temperate forests: arbuscular mycorrhizae and ectomycorrhizae. These two types interact with and affect free-living decomposer microbes in different ways that may lead to differences in nutrient cycling and soil carbon storage. We are currently running experiments to investigate how these mycorrhizal types: 1) affect the amount of mineral-associated soil organic matter, 2) affect the decomposition of leaf and root litter of different qualities, 3) affect the fate of root exudates and subsidies to the soil, and 4) respond to forest disturbances.
What if you could look at earth’s forests from a bird’s eye view and know what was happening to carbon storage in the soil just by knowing each tree species? Our experiments will help soil carbon modelers that are trying to do just that – project future soil carbon storage, using information associated with tree species. Our project aims to help inform these models by investigating how tree species’ mycorrhizal associations can be used for these predictions. This research is being funded by the U.S. Department of Energy.
Improving Soil Carbon Storage in Grazed Fields
Perennial grasses have potential to increase long-term soil carbon storage. Carbon sequestration can help mitigate the pace of climate change. We are researching how the planting of a deep-rooting perennial forage and hay crop called intermediate wheatgrass (Thinopyrum intermedium) may change soil carbon storage, particularly in deep soils. We are working at three beef cattle and dairy farms across Vermont to investigate changes in soil health across the soil profile, up to 1 meter, in response to planting wheatgrass. We will be measuring soil carbon and nutrients and forage quality, before and three years after planting and in controls. Funded through the Natural Resources Conservation Service Conservation Innovation Grant Project, we may discover a new way to improve soil health on pastures in Vermont.
Rains & Redox
Prompted by meteorologic findings over the past two decades, this project asks how observed increases in frequency and intensity of extreme precipitation events in the Northeast US will influence carbon stocks in upland forest soils via changes to redox potentials. We will use a combination of weather monitoring and soil chemistry measurements. By analyzing localized precipitation along with soil moisture, temperature, reduction-oxidation state; and gaseous, aqueous, and solid mineral composition, we hope to illuminate the soil ecological and chemical responses to receiving large quantities of water over short periods of time.
Deep Soil Responses to Global Change
We are working in two long term experiments, CCASE (Climate Change Across Seasons Experiment) run by Dr. Pamela Templer at Hubbard Brook and SWaN (Soil Warming and Nitrogen experiment) run by Serita Frey at Harvard Forest. At these experiments, we have installed soil gas wells to measure how CO2 production at different soil depths is responding to warming. We are simultaneously measuring O2 concentrations to calculate respiration quotients, which can indicate which substrates and microbial processes are contributing to CO2 production.