Date of Award
January 2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
Kathryn Yurkonis
Abstract
The United States Department of Agriculture Farm Service Agency Conservation Reserve Program (CRP) enables producers to voluntarily convert cropland to long-term vegetative cover and is the largest grassland restoration program in the country. The CRP supports several conservation practices that range in the number and types of plant species seeded. Results from small-scale biodiversity experiments suggest that increasing plant diversity should increase aboveground plant biomass and soil function in these sites. However, these plant effects have yet to be quantified at large geographical scales across wide environmental gradients. We used Diversity-Interactions models to determine if the composition of the seeded and observed species pools affected plant biomass and soil functions (soil active carbon, soil aggregate stability, soil bulk density, and water infiltration) in a set of 188 CRP grasslands distributed across nine Great Plains states. Sites were visited once per year from 2021 to 2023. Plant percent cover surveys were conducted at each site in 2021, and plant biomass and soil samples were collected once per summer. I fitted a combination of environmental and plant covariates to each response. Best fit models varied among responses. Unsurprisingly, environmental covariates were consistent predictors of all responses. Seeded plant species richness and functional composition affected soil aggregate stability. Observed plant functional composition and the proportions of key species affected plant biomass, soil bulk density, and water infiltration. These results suggest that seeded and observed plant species richness, functional composition, and key species proportions affect ecosystem functions. Furthermore, these results suggest that broadscale plant effects can be quantified in observational contexts like the CRP across wide environmental gradients. The models used in this study can be used to optimize seed mixes to maximize ecosystem functions and can help us better understand the relationships between plants and ecosystem functions in restored grasslands.
Recommended Citation
Knapek, Jacob, "Quantifying Plant Effects On Ecosystem Functions Across Great Plains Conservation Reserve Program Grasslands" (2025). Theses and Dissertations. 7125.
https://commons.und.edu/theses/7125