Get reliable science

Heterogeneity has recently become a focus for land managers interested in optimizing grasslands for both livestock and wildlife. We sought to increase heterogeneity in northern mixed-grass rangelands by applying spatially-discrete patch burns, which create contrast in vegetation structure and forage quality among recently-burned and unburned areas. Low vegetation stature and high forage quality in recently-burned patches should attract grazing livestock and in turn maintain structural contrast and high forage quality throughout the season. We initiated patch burn-grazing by applying spatially-discrete prescribed fires to patches within larger grazed pastures at two experimental rangeland locations in North Dakota: 8 cattle pastures at the Central Grasslands Research Extension Center (Streeter, ND) and 3 cattle and 3 sheep pastures at the Hettinger Research Extension Center (Hettinger, ND). To determine forage quality and productivity, we clipped vegetation at sampling points once per month during the grazing period. For each pasture, we nested sampling points within ecological sites within patches to determine if our imposed heterogeneity overcame inherent landscape heterogeneity. We determined forage quality of samples using near-infrared spectroscopy. To determine spatial patterns of livestock utilization, we counted fecal pats in the vicinity of forage sampling points at time of clipping. We measured the vegetation structure along transects within each patch using the VOR method. Here we present the pattern of biomass production, livestock use, forage quality, and vegetation structure within and among recently-burned and unburned patches in the summer of 2017. While the benefits of spatial heterogeneity to rangeland biodiversity are well-established, biomass production, vegetation structure, and forage quality address the viability of patch burn-grazing as a livestock production system in northern grasslands.