Title: Livestock Grazing Decreases the Risk and Potential Severity of Wildfires. Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2010
Publication Date: N/A
Technical Abstract: Livestock grazing is controversial in the Great Basin and Intermountain West because these rangelands did not evolve with high densities of large herbivores. However, a greater threat to these rangelands is invasion by exotic annual grasses after wildfires. Grazing, as a modifier of fuels, may influence wildfires. However, the influence of grazing on fuels in these ecosystems remains relatively unknown. We investigated the influence of long-term (+70 yrs) moderate grazing (grazed) and grazing exclusion (non-grazed) on fuels in sagebrush steppe plant communities at eight sites. The non-grazed treatments had more fine fuels and greater continuity of fuels than moderately grazed areas. Accumulations of fine fuels on perennial bunchgrass crowns were approximately 3-fold greater in non-grazed compared to grazed treatments (P < 0.01). Total fine fuel accumulations were more than 2-fold greater in non-grazed compared to grazed sagebrush steppe (P < 0.01). Gaps in fuels were smaller in non-grazed than grazed treatments (P < 0.05). The accumulation and continuity of fine fuels in the non-grazed treatments suggest that non-grazed compared to moderately grazed sagebrush steppe rangelands are more likely to burn. The accumulations of fuels on perennial bunchgrasses suggest that they are at greater risk of fire mortality and this increases the risk of exotic annual grass invasion post-fire. Our results suggest that removing livestock from sagebrush steppe rangelands may further jeopardize sagebrush obligate wildlife species by increasing the probability, continuity, severity, and size of wildfires and facilitating exotic annual grass invasion.