CLASSIFYING ECOLOGICAL TYPES AND EVALUATING SITE DEGRADATION

An analytical method for classifying ecological types was developed an d tested for mountain meadows in central Nevada. Six ecological types were identified by plot sampling of vegetation and soil-site variables . Two-way indicator species analysis and canonical correspondence anal ysis were used to identify ecological types and to compare the discrim inating abilities of different ecosystem components. Each ecological t ype was a characteristic combination of landform, soil, and vegetation . Changes in vegetation and soil conditions were assessed along a grad ient of degradation within one ecological type-the dry graminoid/Cryob oroll/trough drainageway type. Direct gradient analysis was used to di splay changes in plant composition and indicators of site degradation. Plant and soil indicators of degradation were basal cover of vegetati on, standing crop production of 3 key grass species, rates of infiltra tion, and soil compaction. Three states of range degradation were iden tified along the gradient. The grass-dominated state was the most desi rable in terms of forage production, basal cover of vegetation and inf iltration, while the grass/forb/shrub state represented the most degra ded and least productive state.