ARS | Publication request: SOIL NITROGEN MANAGEMENT AND INVASION RESISTANCE

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: December 30, 2008
Publication Date: February 8, 2009
Citation: Vasquez, E.A., Sheley, R.L., Svejcar, A.J., Smith, B.S. 2009. SOIL NITROGEN MANAGEMENT AND INVASION RESISTANCE. 62nd Society for Range Management Annual Meeting. Paper No. 20-11.

Technical Abstract: Invasion by annual grasses, such as medusahead (Taeniatherum. caput-medusae (L.) Nevski), into the Great Basin sagebrush steppe is a major concern of ecologists and resource managers. Maintaining or improving ecosystem health depends on our ability to protect or re-establish functioning, desired plant communities. In frequently disturbed ecosystems, nutrient status and the relative ability of species to acquire nutrients are important drivers of invasion, retrogression and succession. Here, we provide the ecological background of invasion by exotic plants, and then 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. 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 several methods during restoration. In these cases, management may be more sustainable because the underlying cause of invasion and succession is modified in the management process.