Date of this Version
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 Craig Allen
Lincoln, Nebraska, December 2023
A Collaborative Adaptive Management (CAM) Project was started at the University of Nebraska in 2020 to address some of the key uncertainties related to the management of grasslands in the Nebraska Sandhills through stakeholder driven experiments and the adaptive management cycle. Patch-burn grazing was selected by CAM as a management tool to generate heterogeneity across the landscape and promote biodiversity while balancing economic and ecological trade-offs. The patch-burn grazing system was implemented with controlled burns in May of 2022 and March of 2023. Other parties in CAM will be examining the impact that patch-burn grazing has on forage and livestock performance, and early results show an increase in the weight gain of cattle in the patch-burn grazing system. The goal of the research presented here is to understand how the use of patch-burn grazing impacts several ecological aspects of the Nebraska Sandhills. Specifically, this study asks three things 1) does patch-burn grazing negatively impact soil conditions by increasing soil erosion and depleting the thin topsoil of nutrients in burned areas, 2) is patch-burn grazing able to significantly change vegetation structure and promote vegetation heterogeneity, and 3) how does patch-burn grazing affect avian communities, their species diversity, and abundance in the Sandhills? The comparison of soil conditions between burned and unburned was made using erosion pins installed throughout the burned and unburned fields and a series of soil nutrient panels samples taken before and, in the months following the fire. Vegetation structural metrics and function group covers were measured throughout each field in the study. A nonmetric multidimensional scaling (NMDS) ordinal analysis supported by a pairwise comparison using permutational multivariate analysis of variance (PERMNOVA) was used to examine the difference in vegetation structure between each of the fields in this study. Bird point counts were performed in each field throughout the two years of this study. This data was used to calculate and compare species diversity, community composition, and the abundance of a few select species. NMDS and PERMNOVA were used to explore the differences between the avian communities in each field, while N-mixture models were used to estimate abundance. Patch-burn grazing proves it is able to change the vegetation structure of the Nebraska Sandhills to promote heterogeneity and create more habitat for a diversity of different grassland bird species without compromising soil health. This study provides an understanding of how patch-burn grazing, an under-utilized tool in the Nebraska Sandhills, can be used to support a more heterogeneous and resilient grassland.
Advisor: Craig Allen