approach is appropriate, however, because it avoids the 

 presumption of climax. 



Community types are aggregations of similar plant 

 communities based upon existing floristics regardless of 

 successional status. As with habitat types, community 

 types view the plant community as an environmental 

 integrator, and thus reflect major environmental differ- 

 ences. Community types may either represent climax 

 plant associations or represent successional stages 

 toward climax plant associations. In either event, 

 resource managers in the field must contend with this 

 existing vegetation. Once community types are defined, 

 effort can be directed toward establishing successional 

 relationships and Unking serai community types to 

 known habitat types where appropriate. Meanwhile, the 

 community types can be used as a basis for mapping 

 and resource management planning. 



Community type classifications for aspen lands have 

 been developed within the Forest Service's Intermoun- 

 tain Region for the Bridger-Teton National Forest in 

 western Wyoming (Youngblood and Mueggler 1981) and 

 for the Targhee and Caribou National Forests in south- 

 eastern Idaho (Mueggler and Campbell 1982). This clas- 

 sification extends the earlier efforts southward to 

 describe aspen lands on and near the six National 

 Forests in Utah: Wasatch-Cache, Uinta, Ashley, Manti- 

 LaSal, Fishlake, and Dixie. During the process of struc- 

 turing these aspen-land classifications for the Intermoun- 

 tain Region, concepts have continued to evolve that we 

 hope will enhance their use. Our objective was to 

 produce aspen-land classifications, and supporting infor- 

 mation, that would serve to facilitate multiple-use 

 management in the Intermountain Region. 



METHODS 



The community-type approach to classification 

 development necessitates extensive sampling to ade- 

 quately encompass and replicate the variation in compo- 

 sition of existing vegetation resulting from both abiotic 

 and biotic environmental influences. However, acquisi- 

 tion of quantitative data on stand structure, under- 

 growth productivity, and certain other desired factors 

 can be laborious. Because we did not have the resources 

 to measure Eill stands at the desired intensity and still 

 acquire an adequate number of stands upon which to 

 base a useful classification, we used a dual sampling 

 approach. One person sampled reconnaissance plots by 

 traveling independently from a two-person crew responsi- 

 ble for sampling the sep£irate and more time-consuming 

 intensive plots. On the reconnaissance plots, species 

 composition was estimated, and some environmental fac- 

 tors were characterized. The intensive plots yielded data 

 on stand structure, age, productivity, and environment 

 as well as species composition. 



Field Methods 



Aspen stands for sampling were found primarily by 

 traveling forest roads throughout Utah looking for 

 reasonably accessible candidates. We used only two 

 selection criteria: at least 50 percent of the tree canopy 

 cover had to consist of aspen, and the stand had to be 



large enough to contain a single macroplot within an 

 apparently uniform environment. Our intent was to sam- 

 ple the full environmental range where aspen expressed 

 dominance. Neither successional status nor grazing 

 intensity were considerations in stand selection. Thus, 

 although the actual selection of stands was subjective, 

 this selection avoided preconceived bias that could 

 influence the resulting classification. 



Upon selection for intensive sampling, a single 

 1/13-acre (SH-m^) circular macroplot was established in a 

 relatively uniform and representative portion of the 

 stand. Ecotones at stand margins and atypical openings 

 were avoided, as were clonal ecotones where a stand was 

 composed of more than one discernible aspen clone. Tree 

 data by species, collected from the entire macroplot, con- 

 sisted of: an ocular estimate of overhead canopy cover; 

 reproduction as number of stems with heights less than 

 4 inches (1 dc), 4 to 12 inches (1 to 3 dc), and 12 to 55 

 inches (3 to 14 dc); number of stems by 2-inch (5-cm) 

 diameter at breast height (d.b.h.) size classes; and age, 

 height, and d.b.h. of individual trees selected to repre- 

 sent the dominants and other well-defined size strata. 

 We determined species composition of the undergrowth 

 shrubs and herbs by estimating canopy cover by species, 

 based upon careful overall scrutiny of the entire macro- 

 plot. In addition, we estimated canopy cover for the 

 vegetational classes of shrubs, graminoids, forbs, and 

 annuals. Undergrowth biomass was determined by a 

 combination of estimating and clipping current yetir's 

 growth of shrubs below 5 ft (1.5 m) high, and herbs on 

 three sets of microplots randomly distributed on the 

 1/13-acre (314-m^) macroplot. Each set of microplots con- 

 sisted of a cluster of five circular 5.4-ft^ (0.5-m^) plots on 

 which the current growth on four was estimated as a 

 percentage of the fifth, which was then clipped. The 

 clipped material was saved and later dried for 48 h at 

 158 °F (70 °C). The percentage estimates from the four 

 plots in a set were then converted to dry weight. An 

 estimated correction was applied at the time of sampling 

 to adjust the weights for sampling either before or after 

 the time of peak standing crop, as well as to compensate 

 for obvious livestock use. These adjustments were highly 

 subjective but deemed necessary to compensate for obvi- 

 ous production distortions caused by time of sampling 

 and use. Estimated undergrowth production, therefore, 

 was based on 15 microplots per stand. All production 

 values given are dry weights. We determined the follow- 

 ing environmental factors for each intensively sampled 

 stand: elevation, aspect, percent slope, landform, soil par- 

 ent material, depth of melanized layer, and estimates of 

 rooting depth, soil rockiness, and soil texture. We also 

 recorded location, evidence of succession, livestock use, 

 and other interpretative information. 



The considerably more rapid reconnaissance technique 

 consisted of choosing an approximately 1/10-acre 

 (1/25-ha) uniform portion of the stand to be sampled and 

 estimating selected vegetation factors. Canopy cover of 

 each tree species was estimated separately for that por- 

 tion over 4.6 ft (1.4 m) high and the reproduction under 

 this height. Percentage canopy cover for each shrub and 

 herbaceous species, as well as for vegetation classes, was 

 estimated after carefully scrutinizing the area. We 



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