Collaborative Research: How do changes in land cover and climate perturb grassland water and carbon cycles below-ground?

Water plays a crucial role in supporting life on Earth, not only in rivers and lakes, but also within the soil and atmosphere. The way water moves and is stored can affect everything from plant growth to water quality. When it rains, water doesn’t just sit on top of the land; it gets absorbed into the soil to support plants and animals, seeps down to become groundwater, evaporates back into the air, or runs off into streams and oceans. The way water is distributed on the planet is changing due to human activities and global warming, yet it is not fully understood how such changes impact water stored in the ground, plant growth, or how water availability regulates where and how much carbon is stored belowground. To solve this puzzle, this project will measure the movement and amount of water and carbon in a Kansas grassland where the climate is getting wetter, and the land cover is changing where shrubs are encroaching and replacing grasses. The project will train undergraduate and graduate students, as well as a postdoctoral researcher, to collect water, soil, and plant data and bring these data together to understand how the water and carbon cycle are changing. This project will use the Konza Prairie (Kansas, USA) and its long-term research platform of watershed-scale manipulations (e.g., fire and grazing) in a mesic grassland to answer the question: How does concurrent climate and land cover disturbance alter below-ground water and carbon cycle processes, and their interactions? Using an interdisciplinary approach that incorporates new data collection, data harvesting, and numerical modeling the project team will: 1) quantify the degree to which woody encroachment alters soil macropore abundance, preferential flow occurrence, and vertical water fluxes; 2) measure the impact of woody encroachment on groundwater residence times and the fractional sources of water (e.g., interflow, shallow groundwater, deep groundwater) that support stream flow; 3) quantify changes in carbon subsurface processes (e.g., respiration rates, decomposition, weathering) and fluxes; and 4) model the impact of synchronous changes in climate (i.e., precipitation and evapotranspiration) on the capacity for carbon sequestration as woody encroachment progresses in grasslands. By addressing the overarching question in grasslands with intermittent streams underlain by carbonate bedrock, the research will provide transferable knowledge on the ecohydrologic function in systems particularly vulnerable to climate and land cover disturbance.This project is co-funded by the Division of Earth Sciences Hydrologic Sciences program and the Division of Environmental Biology Ecosystem Science program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.