Figure 2 — Three years after fire killed ttie aspen overstory, a dense stand of grasses, forbs, and 

 aspen suckers occupies this Manning Basin site. 



The understory in aspen usually is lush and contains 

 many species palatable to both livestock and big game. 

 Fire may increase at least the herbaceous component of 

 this understory (Bartos and Mueggler 1981) (fig. 2). The 

 attraction of burned areas to foraging ungulates, particu- 

 larly big game, has led to frequent speculation that the 

 forage on these bums is more nutritious than on adjacent 

 unbumed areas. This has been tested and found to be 

 true for many vegetation types. The fiber content is ofl;en 

 lower and the protein and phosphorus contents higher in 

 the regrowth during the first couple years following fire 

 (Blank 1984). However, no test of this hypothesis for the 

 western aspen-shrub community could be found in the 

 literature. Therefore, we conducted an experiment with 

 the following objectives: 



1. To determine nitrogen, calcium, and phosphorus 

 concentrations in aspen sprouts and selected species of 

 grasses, forbs, and shrubs common to both burned and 

 unbumed aspen communities. 



2. To compare in vitro digestibilities for elk and for 

 domestic sheep of these plant species from both 

 treatments. 



MATERIALS AND METHODS 



We selected three sites in the Caribou National Forest 

 about 20 miles (30 km) west of Afton, WY. All three had 

 been prescribed burned in the autumn of 1981. Bum 

 severity ranged fi^om high (Manning Basin site) to moder- 

 ately low (Snowdrift I and II sites). These sites were in 

 the Populus tremuloideslAmelanchier alnifolia — 

 Symphoricarpos oreophilus plant community. These char- 

 acteristic tall shrubs grow within an herbaceous under- 

 story dominated by Calamagrostis, Elymus, Lupinus, or 

 Geranium (Mueggler and Campbell 1982). 



Plant samples were collected during the summers of 

 1982 and 1983 from the burned and adjacent unbumed 

 areas on each site. For the most part, we gathered only 

 those species that made up the majority of forage and 

 were common to both the burned and unbumed areas. 

 Each sample of a species consisted of material from 25 to 

 30 randomly selected plants. Woody plants were sampled 

 by stripping the leaves and terminal segments of the 

 current year's twigs. The entire aboveground portion of 

 grasses and forbs was collected. Samples were immedi- 

 ately weighed to determine moisture content. They were 

 put on ice in the field and fi-ozen later that day. Prior to 

 analyses, they were ovendried at 50 °C, weighed again, 

 and ground to pass through a 1-mm screen. 



2 



