Does fall prescribed burning Artemisia tridentata steppe promote invasion or resistance to invasion after a recovery period
Davies, K. W., R. L. Sheley and J. D. Bates . 2008. Journal of Arid Ecology 72: 1076-1085
Abstract
Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh-bunchgrass communities were used to analyze
the influence of disturbances on invasibility after a recovery period. These communities evolved with periodic fires shifting
dominance from shrubs to herbaceous species. However, fire can facilitate Bromus tectorum L. invasion of these plant
communities. We evaluated the invasibility of A. tridentata ssp. wyomingensis-bunchgrass communities 4 years after
prescribed fall burning at six sites by comparing burned to unburned (control) communities. These communities did not
have B. tectorum present prior to introduction. B. tectorum was introduced at 1, 10, 100, 1000, and 10,000 seeds m² in
burned and unburned communities. B. tectorum individuals established only when introduced at 10,000 seeds m-2. In the
areas seeded at 10,000 seeds m-2, B. tectorum density and cover were more than three-fold higher in the control than
burned treatments (P = 0.04 and 0.08, respectively). Total herbaceous vegetation cover, density, and production increased
with burning (P<0.01, 0.02, and <0.01, respectively). Bare ground and inorganic nitrogen were higher in the control than
the burned treatment (P = 0.02 and <0.01, respectively). Prescribed fall burning of late seral A. tridentata ssp.
wyomingensis-bunchgrass communities stimulated the herbaceous component and increased the resistance of the
communities to B. tectorum invasion 4 years post-burn. However, we do not suggest the use of prescribed burning in
communities where invasive annual grasses are present or in close proximity. We acknowledge that our results would
probably have been drastically different if B. tectorum or other invasive annual grasses had been a component of the plant
communities prior to prescribed burning or became a component immediately after burning.
Key Words
Bromus tectorum, Disturbance theory, Fire, Invasive plants, Prescribed burning, Artemisia tridentata ssp. wyomingensis
