An attempt was made to maximize surficial geology variation 

 within the sample pool by including as many geologic classes as 

 possible within each of the above sample classes. Also, sample 

 quadrangle selection was biased towards quadrangles that included 

 the greatest number of geologic classes within a precipitation/ 

 freeze-free class. Additionally, an attempt was made to maximize 

 the geographic dispersion of quadrangles selected while main- 

 taining the primary objective of maximizing environmental varia- 

 tion. 



Finally, in cases of an equal choice between selecting a 

 quadrangle encompassing primarily private land versus one encom- 

 passing primarily public land, the public land quadrangle was 

 selected. This was done to enhance the ease of land access. 



To minimize the confounding nature of heavy disturbance on 

 vegetation occurrence, areas severely overgrazed, herbicide 

 treated, mechanically disturbed, artificially seeded, or irri- 

 gated were not sampled. Plots were established within portions 

 of stands that appeared to be relatively uniform in topography 

 and vegetation structure. Within an area, one to five plots were 

 chosen from different topographic positions and where judgement 

 indicated a marked change in vegetation composition. 



Plot selection focused on contemporary stands of vegetation 

 without reference to successional relationships among stands. No 

 attempt was made to solely sample remnants of presettlement vege- 

 tation. 



The data were recorded on a Natural Heritage Program Commun- 

 ity Survey Form for each plot. These forms are basically the 

 same as the general plot data and ocular plant species data forms 

 used by the USDA Forest Service (USDA 1987) . Complete lists and 

 canopy cover estimates of vascular plant species were recorded 

 within each 375 m^ circular study plot. Site information such as 

 altitude, slope, aspect, parent material, landform, and erosion 

 type were also recorded for each plot (Table 1) . Soil taxon was 

 recorded when a survey report was available for the site. 



Data Analysis 



Analysis focused on using a combination of classification, 

 to determine community types, and ordination (gradient analyses), 

 to describe general patterns of communities in relation to envi- 

 ronmental factors. Classification was accomplished using two-way 

 indicator species analysis (TWINSPAN; Hill 1979a) in the CEP MS- 

 DOS computer package (Mohler 1937) . Ordination was achieved 

 using the detrended correspondence analysis (DCA) and detrended 

 canonical correspondence analysis (DCCA) algorithms in the CANOCO 

 computer package (Ter Braak 1988) . The input data were species 

 cover variables recorded in each plot and, in the case of DCCA, 



