Abstract. Random rearrangement of entry order in three data sets often changed ordination and classification results based on Reciprocal Averaging. Results varied with the data set and method used. Eliminating infrequently occurring species largely reduced, but did not always eliminate, the variability. Overall, results appeared related to data set complexity, the type of data or transformation, and the analysis method used. Detrended Correspondence Analysis had the greatest variability of the ordination methods tested. Results from quantitative data were usually more variable than presence/absence data. Variation in cluster analysis was related to the number of tie values in the similarity matrix. Detailed tests using randomization of entry order of individual data sets with each of the programs to be used are needed to individually assess the effects on the results.; Keywords:; Cluster analysis; DECORANA; Ecological group; Entry order; Environmental gradient; TWINSPAN

Despite the importance of soil characteristics for classifying riparian ecosystem types and evaluating ecosystem or range condition, little information exists on western riparian area soils or the factors that influence them. We examined the effects of drainage basin geology and water table depth on soil morphology and soil physical and chemical properties of meadow sites in central Nevada. We described and analyzed the soils of meadows that occurred in 4 drainages with different geology and that exhibited high water tables (0 to-20 cm from the surface), intermediate water tables (-30 to-50 cm), and low water tables (-60 to-80 cm). Pedons of high water tables sites had thick O e horizons, dark, fine-textured A horizons, no B horizons, and lower C horizons high in coarse fragments. In contrast, pedons of low water tables sites were characterized by deep, dark and organic-rich A horizons, cambic B horizons, and deep rooting profiles. High water tables sites had higher organic matter, total nitrogen, cation exchange capacity, and extractable potassium, but lower pH than low water table sites. Also, high water table sites had lower percentage sand, lower bulk densities, and higher soil moisture retention. The importance of organic matter was evidenced by strong positive product moment correlations for organic matter and total nitrogen, cation exchange capacity, and extractable potassium. Significant differences in pH, extractable potassium and extractable phosphorus existed among drainages that were explainable largely from the parent materials. Drainages with chert, quartzite, and limestone had higher silt and clay, neutral pH, and high levels of extractable phosphorus. Drainages formed in acidic volcanic tuffs, rhyolites and breccia were characterized by coarser textured soils and low pH and extractable phosphorus. In riparian areas, soil water table depth interacts with soil parent material to significantly affect soil morphology and soil physical and chemical properties. Because these factors vary over both large and small spatial scales, differences among sites must be carefully interpreted when classifying ecosystems or evaluating ecosystem condition.

An analytical method for classifying ecological types was developed and 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 analysis were used to identify ecological types and to compare the discriminating abilities of different ecosystem components. Each ecological type was a characteristic combination of landform, soil, and vegetation. Changes in vegetation and soil conditions were assessed along a gradient of degradation within one ecological type-the dry graminoid/Cryoboroll/trough drainageway type. Direct gradient analysis was used to display changes in plant composition and indicators of site degradation. Plant and soil indicators of degradation were basal cover of vegetation, standing crop production of 3 key grass species, rates of infiltration, and soil compaction. Three states of range degradation were identified along the gradient. The grassdominated state was the most desirable in terms of forage production, basal cover of vegetation and infiltration, while the grass/forb/shrub state represented the most degraded and least productive state.

In many riparian corridors of the semi-arid west, stream incision has resulted in lowered water tables, basin big sagebrush (Artemisia tridentata var. tridentata Nutt.) encroachment and the loss of the dominant herbaceous vegetation. To determine the potential for restoring basin big sagebrush-dominated riparian corridors to greater herbaceous cover, a fall prescribed burn on sites with relatively shallow (-153 to -267 cm) and deep (-268 to > -300 cm) water tables was conducted. We evaluated the separate and interacting effects of water table depth and burning on total soil C and N, soil nutrient availability, and soil enzyme activities by microsite (sagebrush subcanopy, sagebrush interspace), and soil depth (ash/liter, 0-2, 2-5, and 10-20 cm). Three years after the prescribed burn, tissue nutrient content in silvery lupine (Lupinus argenteus Pursh) and Douglas sedge (Carex douglasii Boott), by microsite, growing in burned and unburned areas of 1 shallow water table site was measured. Influence of fire on soil attributes was largely limited to the top 5 cm. As a consequence of prescribed burning, deep water table sites lost relatively more N and C from litter horizons and released more aqueous-soluble Ca+2 from 0-2 cm mineral horizons than did corresponding horizons from shallow water table sites. Overall, compared to unburned controls, burning: (1) increased aqueous. extractable S04 2, K+, and KCl-extractable NH4, (2) decreased activities of the enzymes asparaginase, crease and acid-phosphatase, and (3) decreased KCl-extractable N03" and aqueoussoluble ortho-P. Out of 16 measured soil attributes reported, 7 were influenced by a microsite main effect and/or interaction. New tissue of silvery lupine on burned plots had greater N, greater Zn and Fe (only on subcanopy microsites) and less Ca than plants on control plots; new tissue of Douglas sedge had greater S and less Na, P, and Zn. The results indicate that burning alone is an appropriate restoration treatment for shallow water table sites because of minimal C and N loss and increased available nutrients for regrowth of understory herbaceous species. Deep water table sites require a burning prescription that minimizes fire severity because of higher potential C and N loss, and reseeding due to a lack of perennial understory herbaceous species and more xeric conditions.