Collaborative Research - Digging deeper: Do deeper roots enhance deeper water and carbon fluxes and alter the trajectory of chemical weathering in woody-encroached grasslands?

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Within grasslands, woody plants are increasing in cover and abundance. The replacement of grasslands by woody plants can change the way water, nutrients, and metals are stored and move through soil. This project studies these changes in grasslands in Kansas. The project links the fields of water science, rock chemistry and soil chemistry. The project connects the way water moves and is stored in the ground to how soil and rock chemically breaks down. Investigating how roots of woody plants altered water flow in the ground is important to understanding how Earth will respond to future changes in climate. This research provides training across different fields of science including geology, biology, and chemistry. Educational materials will be developed for all grade levels including K-12 and college. The goal of this research is to understand how roots respond to changes in climate and land use, and how roots control the movement of water and nutrients through landscapes. Specifically, this research studies how deeper roots associated with woody plant encroachment enhances transport of water and carbon to greater depths, increases the water residence time in the subsurface, and enhances the potential for weathering at depth. To accomplish this goal, integrated field and modeling approaches will be conducted at the watershed scale. Data will be collected at the Konza Prairie (KS, USA), where long-term burning experiments have resulted in the encroachment of woody vegetation. This research relies on: 1) long-term measures of vegetation cover, stream discharge, water isotopes, and water solute chemistry, and 2) new measurements of the subsurface including root density and distribution, soil structure, soil water potential, soil gas concentrations, and solute chemistry. Collectively, this research links water residence time to fluxes of nutrients. The project partners with the Konza Environmental Education Program to provide educational materials and training on woody plant encroachment into prairies. An online modular toolbox for water quality and quantity is developed for undergraduate and graduate students.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.