Dissertation - Open Access
Doctor of Philosophy (PhD)
Natural Resource Management
Patricia S. Johnson
livestock, prairie dogs, remote sensing
A major constraint of beef production within the Standing Rock Reservation has been identified as a reduction in rangeland quality due in large part to wide-scale colonization by black-tailed prairie dogs (Cynomys ludovicianus). The desire exists within the community to design a holistic framework which incorporates livestock management with the goal of increasing production and rangeland health while still maintaining increased diversity associated with prairie dogs. Prairie dogs reduce the carrying capacity of cattle on rangelands by up to 50% on occupied hectares through direct consumption of vegetation and waste due to clipping to improve detection of predators. Livestock stocking rates that do not account for the level of prairie dog occupation can result in a reduction in animal performance and a further decrease in rangeland productivity due to overgrazing. Research is needed to understand season-long use of grazing cattle on and off prairie dog towns to better inform land manager decisions aimed at reducing over-utilization of grasslands and allowing higher production of livestock. This dissertation study was part of a larger study that was conducted in northcentral South Dakota from 2012 to 2016. This dissertation sub-study was designed to evaluate the impact of prairie dogs and cattle on plant community production and composition, and to determine impacts of colonization on livestock grazing behavior, diet quality, and forage intake. Three pastures with varying levels of prairie dog occupation (0%, 20%, and 40%) were studied. Pasture stocking rates were adjusted to account for the level of forage removed by prairie dogs (50%) on active colonies. Two study treatments were evaluated: Ecological Site (n=3) and grazing treatment (n=4). Ecological sites (ES) were Shallow Loam, Loamy, and Thin Claypan. Grazing treatments included two in off-town locations (non-graze (NG) and cattle only graze (CG)) and two in ontown locations (cattle and prairie dog graze (CPD), and prairie dog only graze (PD)). These treatments and their interactions were evaluated to determine their effects on vegetation (e.g. standing crop, diversity, species richness, etc.) and livestock (e.g. animal weight gains, diet quality and quantity, etc.) parameters. Goals of the dissertation herein are to understand 1) the interactions of prairie dogs and livestock on plant communities and 2) the impact of prairie dog occupation on livestock production. Objectives of this dissertation are: 1) Evaluate plant community response to grazing on and off prairie dog towns to determine how livestock and prairie dogs alter plant community production and composition; 2) Develop strategies that enable identification of plant communities of interest on and off prairie dog towns using remote sensing techniques ; 3) Develop methods to utilize programming tools for efficient processing of GPS collar data ; 4) Evaluate relationships between plant communities and cattle grazing locations to identify patterns and trends in livestock grazing behavior throughout the growing season; 5) Evaluate diet nutrient composition and intake by cattle on plant communities on- and off-town over the grazing season; 6) Develop a framework of cattle nutrient consumption in pastures with varying levels of prairie dog occupation; and 7) Synthesize existing research and results from this dissertation to explore potential synergism between prairie dogs and cattle on the landscape from a systems approach. Vegetation analyses show a significant difference in standing crop biomass between grazing treatments, with sites grazed only by cattle having 36% more biomass than those grazed only by prairie dogs. Plant community data suggest that prairie dogs have a greater impact on production and species composition compared to cattle; percent composition of C3 grasses was greatest off-town, whereas percent composition of C4 grasses was greatest on-town. An invasive C3 species of concern in the Northern Great Plains, Kentucky bluegrass, was almost non-existent on-town, but increased substantially off-town over the 5 years of the study for all ES; the most dramatic increase occurred on the Thin Claypan ES. Species diversity was not different between grazing treatments, however species richness was generally greatest on-town. Additionally, for the entire duration of the study (2012-2016), 46 species were only observed on-town and 17 only observed off-town out of a total 113 species observed throughout the 5 years of the study. The remote sensing analyses show that Random Forest (RF) models were highly effective at predicting different vegetation types associated with on and off prairie dog town locations (misclassification rates < 5% for each plant community). However, comparisons between the predicted plant community map using separate years indicate 6.7% of pixels on-town and 24.3% of pixels off-town changed class membership depending on the year. The results show that while RF models may predict with a high degree of accuracy, transition zones between plant communities and inter-annual differences in rainfall may cause instability in fitted models. An essential component of evaluating livestock behavior for this study was accomplished using GPG collars that record both location and activity. Traditional methods of hand-processing of GPS data require a large number of steps which are both time consuming and prone to errors. As part of this dissertation, methods were created to streamline the processing of livestock GPS collar data, resulting in a technical note publication. Due to the open source nature of Program R, custom functions can be created to merge GPS collar data, GIS data layers, and behavior algorithms to improve data processing efficiency. Plant communities of interest for the livestock behavior and intake components of this study were identified as grass-dominated on-town sites (PDG), forb-dominated ontown sites (PDF), and grass dominated off-town sites (NPD). Livestock behavior analyses from this study show cattle slightly prefer grazing on prairie dog towns, with shifts occurring to off-town locations over the duration of the grazing season. Crude protein (CP) content from diet samples for PDF sites were significantly greater than for PDG and NPD sites. Little difference in many of the diet metrics existed, however, between grass dominated sites (PDG and NPD). Despite higher CP content on forb dominated sites on-town (PDF), intake levels were depressed on these communities due to high bare ground and low vegetation production. Individual livestock performance (average daily gains) averaged over the entire length of the study, were 0.74 kg. /day for the 0% occupied pasture, 0.86 kg. /day for the 20% occupied pasture, and 0.85 kg. /day for the 40% occupied pasture. Reduced stocking rate in prairie dog pastures may have contributed to greater individual animal performance. Higher livestock performance for the prairie dog pastures is potentially due to access to a more diverse diet. Reduced stocking rates in prairie dog pastures, however, resulted in a reduction in overall livestock production in terms of kg / ha. At low levels of colonization in pastures, livestock may potentially benefit from increased diet selection, however, reduction in plant biomass on town may negate any potential gains at higher levels of colonization. The results from this study were combined to take a systems approach to understanding the impacts and interactions of prairie dogs and livestock on plant communities, and the impacts of prairie dog occupation on livestock production in northern mixed-grass prairie ecosystems. Our results indicate that having both on-town and off-town plant communities within a pasture can increase biodiversity and heterogeneity at broader landscape scales. Differences in plant community composition may increase diet diversity for grazing livestock, potentially benefiting individual animal gains, provided forage quantity is not limited. At low levels of colonization, livestock production may only be minimally impacted while still realizing benefits to biodiversity.
Number of Pages
South Dakota State University
In Copyright - Educational Use Permitted
Brennan, Jameson Robert, "Prairie Dogs and Livestock in Rangeland Systems: Balancing Biodiversity and Production in the Northern Mixed-Grass Prairie" (2019). Electronic Theses and Dissertations. 3670.