Natural Resources, School of
First Advisor
Dr. Daniel R. Uden
Date of this Version
Spring 5-3-2023
Citation
Bauloye, D. S. (2023). Application of Screening in Rangeland Monitoring: Quantifying Early-Warning Signals of State Transitions in Nebraska. (Master's thesis, University of Nebraska-Lincoln, Lincoln, Nebraska, USA). Retrieved from https://digitalcommons.unl.edu/
Abstract
Woody encroachment, desertification, and exotic annual grass invasion are regime shifts (i.e., state-transitions) with detrimental effects on ecosystem health and services in grasslands of the North American Great Plains. Traditional approaches to rangeland monitoring are capable of detecting regime shifts after they have already occurred (i.e., diagnosing them); however, proactive management requires earlier warning. Regime shift screening is a new approach to rangeland monitoring capable of providing earlier warning of regime shifts. Regime shift screening proposes assessing the presence, persistence, and non-stationarity of regime shift signals; however, no studies have systematically evaluated these characteristics in real-world landscapes. In this thesis, I screened 30 allotments within Halsey National Forest (Chapter 1) and the 23 Natural Resource Districts (NRDs) of the State of Nebraska (Chapter 2) for three notorious rangeland regime shifts—woody encroachment, desertification, and exotic annual grass invasion—from 1984 to 2020, using spatial covariance between rangeland functional group combinations as a screening metric. Halsey allotments and Nebraska NRDs were screened at three scales (i.e., moving window sizes) to determine the number of scales at which different regime shifts occurred in space and time and to assess the efficacy of differentiating between stationary and non-stationary regime shift signals. For Halsey allotments, screening results were compared to time series tests of changes in functional group percent cover estimates (i.e., regime shift diagnosis). Results varied across space, time, scale, and transition types; however, woody encroachment regime shifts occurred over the strong majority of sites and scales, while desertification and exotic annual grass invasion signals occurred less frequently and at smaller scales. Collectively, my results support the use of regime shift screening for early warning of regime shifts in rangeland monitoring.
Adviser: Daniel R. Uden
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Daniel R. Uden. Lincoln, Nebraska: April 2023.
COPYRIGHT © 2023, Daniel S. Bauloye