METHODS 



The 84,000 acres of the middle Gros Ventre drainage selected for this study con- 

 tained most of the aspen stands influenced by wintering elk (fig. 4). Within this area 

 100 sample plots were located by a method in which one plot occurred at random within 

 each 33.3 acres of the 3,330 acres of aspen type delineated on the Forest Service 1956 

 Timber Type Map. Each plot was circular and 1/20 acre in size. Aspen ages were 

 estimated by increment cores extracted at the 10-inch height from two trees containing 

 wood sound enough for ring analysis and located nearest the plot centers. Ring counts 

 were made in the laboratory with the aid of the acid-phloroglucinol staining technique 

 of Patterson (1959). All aspen trees (individual stems taller than 10 feet) within 

 plots were tallied by 6-inch d.b.h. size classes and condition classes: i.e., live, 

 died in the current season, or died before the current season. Trees were assigned to 

 current year mortality if unweathered dead leaves still remained in the crown. Dead 

 trees that had fallen to the ground were not included in the sample unless they were 

 windfall of the current season. 



Sampling began in August 1970 and was completed in September, before fall colora- 

 tion. This short time span insured a fairly comparable estimation of current mortality 

 on all plots. Special efforts were made to record indicators that might suggest the 

 cause of mortality in both classes of dead trees and the presence of injury or disease 

 on all trees. Aspen sprouts within the plots were tallied, their heights determined, 

 and any evidence of injury from browsing, insects, or diseases was recorded. The 

 presence and ground coverage provided by young conifers, conspicuous shrubs, grasses, 

 and forbs were also noted since understory vegetation can provide clues as to the 

 degree of inherent stand stability and disturbance. 



4 



