COS 262-1 - Ungulate selection of varying time since fire in single and multi-species pyric herbivory

Abstract: Woody plant encroachment (WPE) – the conversion of grasslands and savannas to a woody dominated system – is a major threat to grasslands worldwide. Within the South-Central Great Plains, USA, WPE has increased dramatically within the last 30 years resulting in a conversion from grasslands to forested systems. Here we discuss a management technique that could allow grasslands, threatened with conversion to forests, to become more resilient and economically more viable, through the fire-grazing interaction (i.e., pyric herbivory). In 2020, we established 6 pastures (45-60 ha) at the Oklahoma Research Range Station (OSU-RRS) to compare single (n=3) and multi-species (n=3) pyric herbivory. Stocking rates for the pastures were similar across the two treatments (0.83 ha/AUM) We divided each pasture into 6 sections, without cross-fencing, and burned two patches each year for a 3 year time since fire (TSF) interval. Our objective for this study were 1) determine TSF patch selection by species and 2) evaluate cattle productivity performance.

Our results suggest that cattle select for the more recently burned patches (0-5 months time since fire) and goats select for older patches (6-18 months TSF). Between the two treatments, cattle patch selection did not significantly differ with the addition of goats. Goat patch selection was driven by fire, but at a longer TSF interval. Previous research suggests that shrubs and woody plant material increase nutrient quality by 6-12 months TSF, potentially attracting browsers like goats. Cattle performance, measured by average daily weight gain (ADG), resulted in significantly higher multi-species pyric herbivory ADG compared to single-species pyric herbivory. These results can be beneficial to conservationists and landowners combatting woody plant encroachment within the South-Central Great Plains.