Patch burning effects on grazing distribution

Abstract

Post-fire forage growth is known to be a strong attractant for large herbivores. However, fire has generally been avoided as a grazing distribution tool for fear of localized over utilization of forage resources. Our objectives were to examine whether forage utilization was affected by season of burn, determine cattle grazing preference for burned sites relative to non-burned sites, determine forb response to patch burning, and describe the relationship between end-of-season standing crop and distance from burned sites. Sixteen, 4-ha plots were burned in mid-November or mid-April and left exposed to cattle grazing for the duration of the growing season. Burn treatments were blocked within pastures to allow individual herds access to fall-burned, spring-burned, and non-burned sites. Standing crop estimates for grasses, forbs, and total herbage were made in September by clipping on burned sites and at 50, 100, 200, 400, and 800 m distant from the plot's edge. Standing crop was also sampled in exclosures on burned and non-burned sites. Cattle showed no preference for one burn season over the other. Cattle were strongly attracted to burned sites, reducing grass standing crop 78% within burns compared to 19% outside the influence of burns. Grass standing crop decreased in a predictable manner with proximity to burned plots. Forbs increased 60% to 1,095 kg ha-1 on grazed burned plots, but were unaffected by distance from burns. Patch burning can be employed as an effective, inexpensive grazing distribution tool.