|Clements, Darin - Charlie|
Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/11/2005
Publication Date: 2/17/2006
Citation: Clements, C.D., Young, J.A. 2006. Loss of critical browse communities on the Sheldon National Wildlife Refuge [abstract]. Proceedings Society for Range Management 59:46-47. Febuary 12-17, 2006, Vancouver, British Columbia.
Technical Abstract: Mule deer (Odocoileus hemionus) are the only declining big game species in North America. Loss of habitat is a critical factor in this decline. Mule deer are browsers that in the Intermountain west are dependent on such species as big sagebrush (Artemisia tridentata), antelope bitterbrush (Purshia tridentata) and curlleaf mountain mahogany (Cercocarpus ledifolius). All of these critical browse species have limited or no sprouting following burning in wildfires. Therefore, the interval between burning in wildfires is critical in the browse productivity of mule deer habitat. Over much of the Intermountain west, the increasing distribution and abundance of the exotic, invasive annual cheatgrass (Bromus tectorum) has greatly reduced the interval between recurring wildfires. The Charles Sheldon National Wildlife Refuge (NWR) is relatively unique among existing big sagebrush landscape because of the abundance of native perennial grasses and the removal of grazing by all domestic livestock. Livestock were removed in 1991. The resulting increase in density and cover of perennial grasses provided the continuity of fuel for wildfires to spread among the shrubs. In the Badger Mountain unit of the refuge wildfires re-occurred in 1994, 1997, and 2000. Prior to the 1994 wildfire the density of big sagebrush, antelope bitterbrush, and curlleaf mountain mahogany was greater than 15000 per ha. After the 1994 there was marked recruitment of antelope bitterbrush seedlings on the margins of the burned area, but the 1997 and 2000 wildfires re-burned much of the 1994 burned habitat as well as thousands of acres of adjacent shrub habitats, further eliminating a seed source for shrub recruitment. Currently, the density of shrubs on the area burned in 1994 is about 2500 per ha or 17% of the pre-wildfire levels. The concern is that this habitat will burn again before the shrubs can reach even 50% of pre-wildfire densities. Although antelope bitterbrush and mountain big sagebrush, to lesser degree, show promising signs of continual recruitment and establishment back into the community, the loss of mountain mahogany is disturbingly apparent. Resource managers must be aware of the slow rate of return of these critical browse species following wildfire. The interactions among grazing by domestic livestock, native perennial grasses, critical browse species, and the interval between wildfires is a complex issue that range managers and researchers much address if the decline in mule deer is to be reversed.