|Longland, William - Bill|
Submitted to: Journal of Range Management
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/4/2002
Publication Date: 11/1/2002
Citation: Longland, W.S., Bateman, S.L. 2002. Viewpoint: the ecological value of shrub islands on disturbed sagebrush rangelands. Journal of Range Management. 55(6):571-575. Interpretive Summary: Patches of intact shrubs are often left isolated within large areas that are otherwise devoid of woody plants following large-scale disturbances, such as wild fires. We discuss natural resource values associated with these vegetation "islands", focusing especially on western rangelands dominated by sagebrush. Shrub islands provide sites for plant and animal sspecies that require shrubs for their ixistence - from species casually associated with shrubs in general to those with obligate associations with a particular shrub species. Even if shrub islands can not support a given species over the long term, they may provide important temporary habitat for plants or animals in the general area. Shrub islands generally harbor more species than the disturbed areas surrounding them, and thus they can help maintain or enhance the local diversity of plants and animals following catastrophic disturbances. Shrub islands can also enhance the recovery of vegetation in surrounding disturbed areas by providing seed sources for plants that are removed by the disturbance and by harboring animals that provide important seed dispersal services. The potential ecological goods and services offered by vegetation islands should encourage range managers and wildland fire crews to value and preserve these areas.
Technical Abstract: We discuss potential ecological benefits associated with terrestrial vegetation "islands", giving special attention to islands in disturbed shrub systems dominated by big sagebrush. Shrub habitat islands provide important refugia for plant and animal species that are associates of shrubs - from those that generally require shrub cover to those that have evolved obligate symbioses with a particular shrub species. Even if island are not able to support breeding populations, they may provide essential temporary habitat for maintaining a plant or animal metapopulation or for dispersing animals. Habitat islands are likely to enhance local biological diversity of plants and animals, because they harbor species that are lacking in disturbed areas, and because abrupt structural changes from disturbed to undisturbed vegetation facilitate high levels of species turnover. Finally, habitat islands provide more evenly dispersed seed sources for re-establishment of decimated vegetation within disburbed areas, and they may harbor animal species that provide seed dispersal services. Thus, they should accelerate vegetation recovery after disturbance. Managers and others who may influence how disturbance patterns affect habitat heterogeneity, such as fire crews, should be aware of the ecological benefits of habitat islands.