Trials and tribulations of quantifying hotspots of cattle use in large desert pastures

Authors: Spiegal, Sheri; Estell, Richard - Rick; CIBILS, ANDRES - New Mexico State University; James, Darren; PEINETTI, RAUL - Universidad Nacional De La Pampa; Browning, Dawn; Romig, Kirsten; Gonzalez, Alfredo; LYONS, ANDREW - University Of California; Bestelmeyer, Brandon

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/5/2018
Publication Date: 2/10/2019
Citation: Spiegal, S.A., Estell, R.E., Cibils, A.F., James, D.K., Peinetti, R., Browning, D.M., Romig, K.B., Gonzalez, A.L., Lyons, A.J., Bestelmeyer, B.T. 2019. Trials and tribulations of quantifying hotspots of cattle use in large desert pastures [abstract]. In: Abstract Proceedings of the 72nd Society for Range Management International Meeting, February 10-13, 2019. Minneapolis, Minnesota. p. 340.

Interpretive Summary:

Technical Abstract: Overuse of particular locations by cattle in arid environments is associated with perennial grass loss, lateral soil redistribution, dust emissions, and suboptimal forage utilization. We sought to identify the abundance and distribution of hotspots (i.e., locations with multiple visits of long duration) for two types of cattle (Raramuri Criollo, Angus x Hereford) alternating use of a large desert pasture during four phenologically-defined seasons in 2008. We used Gridded Time-Use Maps in the Time Local Convex Hulls (T-LoCoH) package in R to quantify the distribution of both types during the four seasons. This entailed creating a map for each of 32 cows (4 collared cows x 8 trials), and then creating 8 maps – one per trial – illustrating, per cell, the average number of visits and average duration of those visits. Most hotspots were adjacent to watering points, and they were least abundant during the season with the greatest pasture-level forage production. These results were expected in a general sense, but there were several decision points during the analysis, and had we decided differently, different counts and locations of hotspots would have been identified. For instance, we used expert knowledge to a) select the size of the cells (150 x 150 m), b) define a “visit” (at least one occurrence in a cell separated by at least 12 hours from the previous occurrence in that cell), and c) designate cells as hotspots (cells visited on average > 4 times for > 2 hours). Most analytical methods entail some decision-making, and we found T-LoCoH to be highly useful for our research questions. We seek to discuss the utility of T-LoCoH, and our choices for it, with the SRM livestock tracking community to identify whether there might be guiding principles for all when using the tool to quantify cattle use hotspots.