Using data from the Constancy and Average Coverage tables (Appendix A) 

 and Sorensen's similarity index, the Artr/Agsm/Bogr and Arca/Agsm/Bogr c.t.s 

 have a similarity of 42%. This rather low similarity is in part due to the 

 different dominants, and if the shrubby Artemisias are not considered, the 

 types are 68% similar. If, in addition to the Artemisias , the shared dom- 

 inants Agropyron smithii and Bouteloua gracilis are not considered, the 

 types have a similarity of 51%. 



The reconnaissance data suggested the possibility of A. tridentata/ 

 A. spicatum type, but too few samples (4) fell into this cluster to warrant 

 designation of a community type given the variable floristic composition of 

 the Artr/Agsm/Bogr c.t. Mueggler and Handl (1974) identified an A. tridentata/ 

 A. spicatum habitat type in western Montana. 



Artemisia tridentata Gadl aod. Badlands and scablands may partially be 

 mosaics of community types, but they also contain vegetational complexes 

 which are not amenable to classification. 



The cluster analysis grouped a number of these plots on the basis of 

 A. tridentata dominance. Agropyron spicatum , with an average coverage of 

 nine and six tenths percent and constancy of sixty-seven percent, is the next 

 most abundant species. Other associated species are Eriogonum pauciflorum , 

 Grindel ia squarrosa , and Atriplex confertifol ia . E. pauciflorum and A. 

 spicatum are frequently present in badlands. Bronson et al. (1970) identified 

 a buckwheat community in a glaciated area near the study area. Distichlis 

 stricta was present in about a fifth of the plots. 



Artemisia tridentata badland, often restricted to certain strata within 

 badlands^ is usually associated with some soil development, e.g. 6 to 10 

 inches (15.24 cm to 25.4 cm) of regolith over bedrock. 



Brown (1971) identified some Artemisia dominated badland communities, 

 including an Artemisia tridentata-Aqropyron spicatum community. 



Symphoricarpos occidental is-Rosa arkansana Community Type (Syoc-Rosa 

 c.t. ) . Syoc-Rosa c.t. sites are similar to but moister than most Arca/Agsm/ 

 Bogr c.t. sites. Typical members of the Arca/Agsm/Bogr c.t. are often present, 

 but S_. occidentals and R. arkansana dominate. Coupland (1950) identified a 

 coulee type dominated by Rosa spp. and Symphoricarpos occidental is . 



Some species typically found in decidely moist sites first appear in 

 this type. Among these species are Arctium minus , Asclepias speciosa , 

 Panicum virgatum , Solidago riqida , Urtica d ioica , Elymus canadensis , 

 Glycyrrhiza lepidota , and Rhus radicans . Artemisia ludoviciana and Rati bi da 

 columifera are often present in this type. 



Sufficient attention was not paid to rose identification, and R^. acicularis 

 sometimes may have been identified as R. arkansana on some reconnaissance plots. 



Shepherdia argentea/Symphoricarpos occidental is-Rosa arkansana Community 

 Type (Shar/Syoc-Rosa c.t.) . Sites for the Shar/Syoc-Rosa c.t., usually more 

 protected than Syoc-Rosa c.t. sites, are usually found in the bottom of 

 steep-banked coulees where a combination of runoff, drifted snow, shade, and 

 decreased wind velocity combine to make a habitat suitable to tall shrubs. 



33 



