Rangeland vegetation and soil response to summer patch fires under continuous grazing
Additional Document Info
Prescribed fire is used to reduce woody plant and cactus cover and restore degraded rangelands in the southern Great Plains, but little is known regarding the impact of summer fires. We evaluated the effects of summer fires applied as patch burns in continuously grazed rangeland in north Texas. Vegetation and soil responses were measured on patches burned within grazing units in the summers of 1998, 1999, and 2000 relative to that on adjacent unburned control areas in the same grazing units. Annual rainfall during the study was below average for six burns (1998 and 1999) and average or above for three burns (2000). If average rainfall preceded and followed summer burning, degradation was limited to a modest increase in bare ground which recovered to exceed unburned control levels within 2 years. However, when drought conditions preceded and followed burning, there was an increase in bare ground and the proportion of annual forbs and annual grasses at the expense of perennial grasses. These areas took 3-5 years to recover. Areas burned in any year did not recover until after a season of favorable precipitation. The degree of degradation was proportional to the severity of drought conditions. The fires reduced the cover of honey mesquite (Prosopis glandulosa Torr.), other shrubs and cactus (Opuntia spp.), which facilitated herbaceous recovery, mitigating the negative impacts of burning in summer and the increased herbivory on the burned patches. Increases in herbaceous species composition were positively related to woody plant and cactus reduction following fire treatment. Results suggest that summer burning may be an effective and low-cost means of controlling problem plants, increasing pasture heterogeneity, and reducing herbivore impact on intensively grazed patches. However, before the practice of summer burning can be advocated, research needs to determine if post-burn deferment will facilitate more rapid recovery through regulating herbivory after burning to increase the recovery of litter and herbaceous cover and restore desired herbaceous species composition and production. Copyright Taylor & Francis Group, LLC.