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Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/14/2007 Publication Date: 1/28/2008 Citation: Davies, K.W., Sheley, R.L., Bates, J.D. 2008. Does fall prescribed burning artemisia tridentata steppe promote invasion or resistance to invasion after a recovery period?. Journal of Arid Environments 72:1076-1085. Interpretive Summary: Understanding the impacts of prescribed burning on the ability of cheatgrass to invaded Wyoming big sagebrush-bunchgrass communities after a short recovery period is needed to make informed management decision regarding prescribed burning. We evaluated the ability of cheatgrass to invaded six Wyoming big sagebrush-bunchgrass communities in the fourth year after prescribed fall burning by introducing cheatgrass into burned and unburned (control) treatments. Cheatgrass establishment was greater in the control than burned treatment. The burned treatment had less bare ground and inorganic nitrogen and greater total herbaceous cover, density, and production than the control treatment. Our results suggest prescribed fall burning of late seral Wyoming big sagebrush-bunchgrass communities stimulated the herbaceous component and increased the resistance of the communities to cheatgrass invasion four years post-burn. This information is useful to land managers planning prescribed burns and scientists investigating the function of disturbances in plant communities. Technical 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 four 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. Bromus tectorum was introduced at 1, 10, 100, 1000, and 10 000 seeds*m-2 in burned and unburned communities. Bromus tectorum individuals only established 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 3 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 four years post-burn. However, we do not suggest prescribed burning communities that have invasive annual grasses present or in close proximity, because 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. |
