Cattle grazing distribution patterns related to topography across diverse rangeland ecosystems of North America

Authors: Raynor, Edward; GERSIE, SAMUEL - Colorad0 State University; STEPHENSEN, MITCH - University Of Nebraska; Clark, Pat; Spiegal, Sheri; BOUGHTON, RAOUL - University Of Florida; BAILEY, DEREK - New Mexico State University; CIBILS, ANDRES - New Mexico State University; SMITH, BRITT - Archbold Biological Station; Derner, Justin; Estell, Richard - Rick; NIELSON, R - Eagle Environmental, Incorporated; Augustine, David

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2020
Publication Date: 1/19/2021
Publication URL: https://handle.nal.usda.gov/10113/7239084
Citation: Raynor, E.J., Gersie, S., Stephensen, M.B., Clark, P., Spiegal, S.A., Boughton, R.K., Bailey, D.W., Cibils, A., Smith, B.W., Derner, J.D., Estell, R.E., Nielson, R.M., Augustine, D.J. 2021. Cattle grazing distribution patterns related to topography across diverse rangeland ecosystems of North America. Rangeland Ecology and Management. 75:91-103. https://doi.org/10.1016/j.rama.2020.12.002.
DOI: https://doi.org/10.1016/j.rama.2020.12.002

Interpretive Summary: This article evaluates rangeland beef cattle grazing distribution and behavioral affinities to topographic positions within pastures while grazing during late growing season periods. In this article, we describe the grazing distribution of cattle across seven rangeland ecosystems spanning a 9 to 54 inch annual precipitation gradient in North America. Pasture size and water sources were determined to strongly influence grazing distribution across ecosystems in this study. High unevenness of grazing distribution occurred in pastures with extensive distances to water, low stock density, and more rugged topography. Conversely, more uniform grazing distribution occurred in smaller, well-watered pastures that supported higher stock density (animals per unit area) and gentler terrain. Additionally, we identify a simple topographic index, the topographic position class index, that when combined with GPS-collar data allows managers to determine topographic positions used most frequently by grazing cattle in rangeland pastures ranging from 40 acres in size in subtropical ecosystems to 3950 acres in semiarid ecosystems. The topographic position class index consists of four topographic positions: lowlands, flat plains, open slopes, and upland. In general, cattle grazed lowlands slightly more than flat plains with more variation among study animals for flat plains. Open slopes were grazed slightly less than flat plains, and uplands were grazed the least at all arid and semiarid sites. Based on our analysis, cattle grazed lowlands on average ~120% more intensively than uplands except at the subtropical ecosystem site, Archbold Biological Station in Florida, where upland habitats are preferred grazing sites compared to waterlogged locations in study pastures. Across these diverse rangeland ecosystems of North America, results provide benchmark information on livestock grazing distribution to formulate improvements in adaptive management and decision-making.

Technical Abstract: Livestock distribution in extensive rangelands of North America can present management challenges to land managers. Understanding the role of topography on livestock distribution, within and across diverse rangeland ecosystems, could provide land managers valuable information for adaptive management of livestock to address both conservation and production goals from these ecosystems. Here, we examine the influence of topography on grazing distribution unevenness and intensity of use of beef cattle in seven rangeland ecosystems spanning arid, semiarid, and subtropical environments. We focused on grazing distribution during the late growing season (summer and autumn) periods when topographic variation in rangelands is more coupled to low and non-uniform availability of high-quality forage. Pasture size and water sources strongly influence grazing distribution across ecosystems. High unevenness of grazing occurred in pastures with extensive distances to water, low stock density, and more rugged topography. Conversely, more uniform grazing distribution occurred in smaller, well-watered pastures that support higher stock density (animals per unit area) and gentler terrain. Comparison of two topographic indices, topographic wetness index and topographic position class index, in terms of their ability to predict cattle grazing distribution, revealed that categorical topographic position classes were more effective. For most arid and semiarid rangelands, livestock grazing distributions showed affinities for lowlands and flat plains compared to open slopes and uplands. In contrast to drier rangelands, livestock grazing distributions exhibited preference for upland and sloped areas of subtropical pastures, as low-lying areas with water-inundation likely curtailed selection. Across these diverse rangeland ecosystems of North America, results provide benchmark information on livestock grazing distribution to formulate improvements in adaptive management and decision-making, and incorporate technological advancements in precision livestock management that will facilitate integration of abiotic environmental information with spatial movements of livestock and temporal vegetation dynamics.