Submitted to: Journal of Invasive Plant Science Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2008
Publication Date: July 1, 2008
Citation: Vasquez, E.A., Sheley, R.L., Svejcar, A.J. 2008. Creating invasion resistant soils via nitrogen management. Journal of Invasive Plant Science Management. 1:304-314. Technical Abstract: Invasion by annual grasses, such as cheatgrass, into the western USA sagebrush steppe and the associated increase in fire frequency are major concerns of ecologists and resource managers. Maintaining or improving ecosystem health depends on our ability to protect or re-establish functioning, desired plant communities. In the sagebrush steppe plant communities, replacing annual grasses with phenologically diverse plants would also provide some fire-resistance. In frequently disturbed ecosystems, nutrients status and the relative ability of species to acquire nutrients are important drivers of invasion, retrogression and succession. Thus, these processes offer potential to be modified to direct plant community dynamics toward a desired plant community. The overall objective of this review paper is to provide the ecological background and propose a concept to facilitate the use of soil N management to achieve desired plant communities that resist invasion. Based on the literature, we propose a model that predicts the outcome of community dynamics based on N availability to plants. The model predicts that at low N levels, native mid- and late- seral species are able to successfully out-compete early-seral and invasive annual species up to some optimal level. However, at some increased level of N, early-seral species and invasive annual grasses are able to grow and reproduce more successfully than native mid- and late seral species. At the high end of N availability to plants, the community is most susceptible to invasion and ultimately, increased fire frequency. Soil N-level can be managed by altering microbial communities, grazing, mowing, and using cover crops and bridge species during restoration. In these cases, management may be more sustainable since the underlying cause of invasion and succession is modified in the management process.