Regional Plant Community Differences in the Nebraska Sandhills

Authors

Travis Millikan, University of Nebraska-LincolnFollow

First Advisor

Mitch Stephenson

Second Advisor

Jerry Volesky

Third Advisor

Dan Uden

Date of this Version

5-2022

Citation

Millikan, T.M. 2022. Regional plant community differences in the Nebraska Sandhills. University of Nebraska-Lincoln.

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: Agronomy, Under the Supervision of Professor Mitchell Stephenson. Lincoln, Nebraska: May, 2022

Copyright © 2022 Travis Millikan

Abstract

The Nebraska Sandhills is very valuable to the state of Nebraska, representing one of the most in-tact and largest grassland ecosystems in temperate regions in the world. Rangeland managers must understand plant community dynamics across the Sandhills to better inform management decisions. The first objective of this study was to evaluate plant community variability on upland Sands ecological sites across different precipitation zones in the Nebraska Sandhills. The second objective of our study was to utilize the Rangeland Analysis Platform (RAP) to examine spatial and temporal variability in biomass production and cover on pastures of ranches analyzed in the first objective across different regional precipitation zones. Frequency of occurrence, dry-weight rank (DWR), and cover point data were collected on 14 working ranches across low precipitation (LPZ), moderate precipitation (MPZ), and high precipitation (HPZ) from 2019 to 2021. Regional differences were found in species frequency and DWR across all years, establishing two distinct plant communities. The LPZ plant community was characterized by prairie sandreed (Calamovilfa longifolia (Hook) Scribn.), sand bluestem (Andropogon gerardii spp. hallii (Hack.) Wipiff), and sand dropseed (Sporobolus cryptandrus (Torr.) A. Gray); whereas plant communities in the MPZ and HPZ were characterized by little bluestem (Schizachyrium scoparium (Michx.) Nash), Scribner’s rosette grass (Dichanthelium oligosanthes var. scribnerianum (Nash) Gould)., and western ragweed (Ambrosia psilostachya D.C.). Remote sensing data collected from the RAP on the same 14 ranches was used to compare biomass and cover across precipitation zones from 1984-2019. Regional differences were found in mean biomass, bare ground, and perennial forbs and grasses cover, as well as in the response of these variables to annual precipitation. Biomass production was lowest in the LPZ and highest in the HPZ. Bare ground was higher and perennial forbs and grasses cover was lower in the LPZ than the MPZ or HPZ. Bare ground and perennial forbs and grasses cover in the LPZ had a greater response to annual precipitation than the MPZ or HPZ, where cover in the HPZ did not demonstrate large responses to these variables. This research highlights the regional variability that exists on upland plant communities in the Sandhills.

Advisor: Mitch Stephenson