ECOLOGICAL CLASSIFICATION AND CUMUIATIVlE SOIL EFFECTS

The Northern Region of the Forest Service, US. Department ofAgricdture, has developed an efficient and consistent method fbr assessing cumulative effects of management practices on the soil and vegetation maurces it manages. Ecological classification and analysis constitute the basis ofthis method Sirtoe many of the management activitks in the Regton alter the present oegetatian of a site (and ronsequently its values fir a variety of resoure u8es) an understanding ofplant succession relationships is critical to proper cumulative effects analysis. The ecological upp m h to cumulative effects analysis presented in this paper has proven effective in the Northern Region and is applicable to other wildland areas. The Forest Service has recently developed general guidelines (USDA FS 1988) for utilization of ecological classification and mapping in National Forest planning. This approach to land-use planning utilizes basic concepts of ecological classification (RISC 1983) in defining lands with similar potentials for management. National direction for a systematic approach to ecological analysis of cumulative effects has not been developed. The primary objective of this paper is to discuss how emlogical classification may be used in assessing the cumulative effects of management practices upon a variety of resources (for example, soil productivity, wildlife habitat, cattle forage, and watershed hydrologic function). A secondary objective is to describe some of the analysis software the Northern Region of the Forest Service uses in ecosystem cumulative effects analysis. 1 ECOLOGICAL CLASSIFICATION Most ecological classifications utilize indicator plant species to describe environments with similar potantials for management. Habitat type classification based upon potential vegetation (associations) (Dauknmire 1952,1968; Hironaka and others 1983; Jensen and others 1988; Pfister and others 1977) is an example of ecological classification that is widely used by various land management agency personnel, since relatively few diagnostic species are required to determine a site's ecological potential. In developing habitat type classification, minimally disturbed late-sera1 (potential natural community) or climax plant I Paper presented at the Symposium an Management and Roductivity otWestern+Montane Fotest Soils, Boise, ID, April 10-12, IWO, Mark E, Jenaen is Regional Soil Scientist, Nsrthan w o n , Forest Service, U.S. Ilepartment of Agricultu~, Missoula, MT 69807. 21 8 communities are sampled to determine which combinations of plant species indicate distinctive environments for management ( E s t e r and others 1977). Vegetation, soils, and other s i b information are collected at sampled plots to fully describe the environment indicated by a given habitat type. Occasionally the range of environment that a habitat type occupies is sufficiently broad that i t is necessary to further delineate it into a smaller classification unit to meet management needs. Such delineations are referred to as ecological sites by the Range Inventory Standardization Committee (RISC 1983), ecological types (site types) by the Forest Service (USDA FS 1988), or range sites by the Soil Conservation Service (Shiflet 1973). Ecological sites, ecological types, and range sites are similar in that each represents kind of land with a specific potential natural community (a habitat type) and specific physical site characteristics, differing from other kinds of land in its ability ta produce vegetation and to respond to management" (RISC 1983). Hierarchical levels of ecological classification may be developed to describe land potential for specific management needs. For example, in broad regional analysis, description of land potential to the formation level of vegetation classification (for example, grassland and forestland) may be adequate for planning purposes. In detailed prcject work site types, ecological types, ecological sites, or range sibs are commonly used to describe the land's potentials for management. The hierarchical ecological classification levels used by Forest Service personnel of the Northern Region (Hann and others 1988) allow for flexibility in describing land potential dependent upon analysis scale and precision of interpretation needs (table 1). PLANT SUCCESSIONAL CIASSIFICATIONS Once ecological classification units are described for an analysis area successional plant communities are sampled to denote the various types of communities and successional pathways that may exist within a given ecological unit. Paired-plot sampling is commonly employed (Amo and others 1986), where treated stands of vegetation and adjacent untreated "controls" are sampled to facilitate accurate assessments of the ecological unit (on the control stand) and the successional plant community response of the treated stand. Vegetation, soil, site, and disturbance information (Hann and others 1988) are collected a t each plot in this approach. Community analysis (Keane and others 1988) of plot data is performed to combine plots into similar #existing vegetation' classification groupings. Ordination software (for example, DECORANA and TWINSPAN, Hill 1979a,b) Table 1-Description of hiirarchii emlogical classification levels uflued by the Forest Service Northern Region (Hann and others 1988) Classification Example Appropriate Potential level name analysis scale cattle forage Emregion Northern 1 :50O,OOO R d e s Gewlimate Moist, ash1 :250,MH3 zone influenced