|Herrick, Jeffrey - Jeff|
Submitted to: Society for Ecological Restoration Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/19/2003
Publication Date: N/A
Technical Abstract: Degradation of arid ecosystems is often signaled by changes in the distribution of soil and water resources and by changes in plant species composition. For example, shrub invasion of grassland typically leads to resource redistribution into larger resource islands that are more widely spaced and more different from the surrounding matrix than those associated with grasses, while increased grass cover has the opposite effect. In both cases, positive feedbacks often develop, reinforcing the altered resource distribution and increasing resistance to management efforts to restore the preexisting plant community. Changes in vegetation spatial structure can alter other important ecosystem processes as well. In parts of the western USA, the more continuous fuel of cheatgrass increases fire frequency, extent and intensity, which is unfavorable for most shrub restoration. In shrublands at the Jornada Experimental Range in southern New Mexico, the larger interspaces between shrubs allow increased erosion, which may hinder grass establishment. Managed redistribution of resources, such as concentrating resources in grasslands to encourage the establishment of shrubs or reducing the spatial heterogeneity of resources in shrublands to promote the establishment of grasses, may be an effective component of restoration projects. The effectiveness of manipulating the spatial distribution of resources for the restoration of shrubs in cheatgrass-dominated grasslands and the restoration of grasses in mesquite- and creosote-dominated shrublands is predictably influenced by site and species characteristics and by the degree to which important ecosystem processes, such as fire and erosion, are modified by changes in the spatial distribution of resources.