the northern limits of its distribution. It also represents 

 ]urupems scopulorum as dominant in a low, rounded 

 growth form. It is not known if the peculiar growth 

 form is genetically- or enviroimientally-induced, i.e, 

 whether the plant association is appropriately 

 recognized as discrete from all others. The rank may be 

 elevated accordingly. 



The Wyoming big sagebrush/ western wheatgrass 

 shrubland {Artemisia tridentata ssp. wyomingensis I 

 Pascopyrum smithii Shrubland) is also near its 

 northernmost extent, subject of biogeographic interest, 

 and in notably good condition. The Nuttall's saltgrass 

 barrens (Puccinnellia nuttalliana Sparse Vegetation) 

 signifies an under-documented vegetation type of the 

 northern plains. Wildlife values were not evaluated. 

 Overall values are enhanced by the continuity with 

 native vegetation on all upland borders. 



LAND USE: 



The area is grazed by livestock. The current condition 

 suggests that it is part of secondary range or a grazing 

 regime that maintains good ecological condition. The 

 area lies north of The Pines Recreation Area. Signs of 

 recreational use that were noted include hunter and 

 limited OHV use. 



MANAGEMENT COMMENTS: 



There are few exotic species in this habitat, with the 



exception of yellow sweetclover {Melilotus officinalis). It 



is widespread but sparse throughout most of the area, 



and particularly abundant along the ephemeral 



watercourses. 



There were no signs of fire in the landscape. Fire is 

 lethal to ]uniperus scopulorum under most conditions, a 

 species that is highly-combustible whether it is dead or 

 alive. 



Hell Creek Potential Research 

 Natural Area 



environment: 



This area includes rolling uplands at the head of Cold 

 Turkey Coulee but could certainly be expanded to 

 include some of the surrounding highly dissected 

 Missouri Breaks terrain. The climate is essentially 

 Continental (refer to the characterization of the 

 Missouri River Bottomland on the basis of Haxby 18 

 SW and Roy 24 NE Mobridge, Montana.) All of the 

 landscape is underlain by sedimentary formations. The 

 highest have sandstone caprock and the rest are various 

 shale and mudstone members that weather to fine- 



textured soil. Thin, carbonate rich lenses occur 

 sporadically. 



VEGETATION: 



Hell Creek is an area notable for the fact that a 

 relatively recent wildfire has burned much of the 

 upland, rolling portion of the landscape and removed 

 the once-dominant Wyoming big sagebrush (Artemisia 

 tridentata ssp. wyomingensis) . The terrain surrounding 

 the uplands portion is highly dissected and erosive, 

 dropping off into badlands, and supports primarily 

 Pondorsa pine -dominated types, including ponderosa 

 pine / sun sedge (Pinus ponderosa I Carex inops) and 

 badlands slopes with sparse shrub cover. 



Pascopryrum smithU - Nasella viridula 



Herbaceous Vegetation 



[PASSMI-NASVIR] 



western wheatgrass - green needlegrass grassland 



Much of the landscape bordering the Missouri Breaks is 

 believed to have been occupied by Wyoming big 

 sagebrush / western wheatgrass - green needlegrass 

 shrubland (Artemisia tridmtata ssp. ury<yminger\sis I 

 Pascopyrum smithii - Nasella viridula) that has been 

 burned. This had the result of killing all of the A. 

 tridentata, sometimes completely consuming the crown 

 and main stem to ground level, and leaving the 

 landscape dominated by grasses as a serai community. 

 The upland component of this landscape is 

 characterized as gently swelling benches to moderately 

 rolling lands with many different exposures, all of 

 which support this plant association, making it a 

 prevailing type. Soils are derived from fine-grained 

 sedimentary strata (shale?) and are primarily silty clay 

 loams. 



The length of time since fire is difficult to determine 

 but most of the landscape that once supported 

 Artemisia tridentata ssp. \xiyomingensis as a dominant, as 

 inferred from density of sagebrush skeletons, is only 

 very slowly returning to that status. No Artemisia 

 tridentata seedings were found on the plot and orJy the 

 merest traces of fringed sage (Artemisia filifolia) and 

 broom snakeweed (Gutierrezia sarothrae) were noted. 

 The grass component strongly dominates this serai 

 phase; western wheatgrass {Pascopyrum smithii) is 

 relatively evenly distributed throughout the stand and 

 its cover (currently 40-50%) may still be increasing 

 following the bum (see Hansen and Hoffman 1988 for 

 a comparison of grass production with and without A. 

 trideruata) . The appreciable cover of green needlegrass 

 (Nasella viridula) indicates the relative mesic, 

 productive nature of this site. Threadleaf sedge (Carex 



17 



