Dr. Morse is broadly interested in understanding and predicting ecosystem responses to environmental changes, particularly human-mediated disturbances, to test our ecological knowledge and to inform environmental decisions. She studies greenhouse gas emissions and nutrient biogeochemistry—primarily nitrogen (N) and carbon (C) in soils and water—to determine how ecosystem processes involving these nutrients change along environmental gradients and following disturbances such as land use change. Her work spans the terrestrial-aquatic interface, from nothern hardwood forests to tidal freshwater marshes, as well as urban lawns and streams, forested and restored coastal wetlands, and mining-impacted streams. As a biogeochemist, she works with collaborators and techniques from many disciplines, including ecosystem ecology, hydrology, statistics, microbial ecology, soil science, modeling, and remote sensing.
Her doctoral dissertation addressed the question of whether re-flooding former agricultural lands for wetland restoration in coastal North Carolina would lead to increased greenhouse gas emissions from these sites. Emissions of nitrous oxide, one of the most potent biogenic greenhouse gases, were expected to increase through higher denitrification in wetter, nitrogen-rich soils. She and her colleagues found that nitrous oxide fluxes from the restored wetland did not exceed fluxes from nearby agricultural fields and forested wetlands, and they measured water quality improvements downstream of the restored wetland.
Dr. Morse's research focuses on soil denitrification in the northern hardwood forests in Hubbard Brook Experimental Forest, New Hampshire. Elevated N deposition across the northeast US has altered N cycling in recent decades; to fully understand the consequences of N deposition, we need to estimate denitrification rates more accurately. Using a new system to measure dinitrogen and nitrous oxide production in intact soil cores, the measurements gathered will provide new data for an updated Northeast US nitrogen budget.
Dr. Morse is also investigating how soil ecosystem processes, including denitrification, respond to differences in winter climate in northern hardwood forests. Differences in aspect (north- versus south-facing slopes) and in elevation lead to differences in snow accumulation and soil freezing, which are likely to strongly influence N cycling by soil microbial communities and N availability for plants.
Dr. Morse has joined collaborators in the Baltimore Ecosystem Study for two new projects. In the first, the goal is to apply methods for estimating soil denitrification and greenhouse gas emissions to stormwater management structures in Baltimore, to estimate the impact of these structures on the N budget of the Gwynns Falls watershed.
In the second project, a team of scientists from six cities (including Baltimore) across the US is investigating whether urbanization leads to ecological homogenization, such that residential yards in different cities are more similar to one another than to their previous land use (forest, desert, etc.), in terms of plant communities, soil properties, and other variables. This project was recently the subject of a piece in the New York Times magazine.