filifoUa) and bluebunch wheatgrss {Pseudoroegneria 

 spicata) are also important grasses in the plot and across 

 the stand. The forb component is diverse but no one 

 species is represented by more than a trace. Of the 

 native forbs, prairie smoke (Geum triflorum), shaggy 

 fleabane (Erigeron pumilis) , scarlet globemallow 

 {Sphaerakea cocdnea) and dotted blazing-star {Liatris 

 punctata) appeared to the most consistently distributed 

 across the landscape. [Plot NHMTECRIsI98SC0011] 



Artemisia tridentata ssp. wycrmingensis I Pseudoroegneria 



spicata Shrubland 



[ARTTSW / PSESPI] 



Wyoming big sagebrush / bluebunch wheatgrass 



shrubland 



The representation of this association is highly 

 dependent on the extent of coarser-textured substrates. 

 Within the Hell Creek area this association is found in 

 small patches confined to the uppermost portions, 

 usually having western or southern exposures, of gentle 

 slopes that are capped with a sandstone member of the 

 local mix of sedimentary strata. Soil texture ranges 

 from fine sandy loam to fine sands. 



Wyoming big sagebrush (Artemisia tridentata ssp. 

 wyomingensis) dominates the shrub layer but its cover is 

 generally not sufficient (20% or less) to place these 

 stands as shrublands in the national classification. 

 Fringed sage (Artemisa /rigicia) , yucca (Xucca glauca) 

 and fragrant sumac (Rhus aromatica) are regularly 

 present with cover usually less than 1 or 2 percent. 

 Within the plot, threadleaf sedge (Carex fiUfoUa) rather 

 than bluebunch wheatgrass (Pseudoroegneria spicata) is 

 the dominant granunoid, but across the local 

 representation of this type dominance shifts among 

 three graminoids, also including needle-and-thread 

 (Stipa comata). This description of the type differs from 

 that of Hansen and Hofftnan (1988) for southeastern 

 Montana in which Pseudoroegneria spicata is uniquely 

 dominant and may be an artifact of the dissected 

 terrain or it reaching the margins of its distribution. 

 The forb component is shared with the adjacent 

 PASSMI - NASVIR community, with the exception of 

 silver-leaved scurf-pea (Psoralea argophylia) a species 

 well known to favor sandy substrates. [Plot 

 NHMTECRN98SC0012] 



Other VegetationTypes: Little bluestem (Schizachyrium 

 scoparium) is a localized dominant on coarse-textured 

 knolls in the area. 



The presence of ponderosa pine (Pinus ponderosa) in 

 surrounding lands is taken to represent the Pinus 



ponderosa I Carex inops Woodland. In addition, limber 

 pine (Pinus flexiUs) is known from ridgelines with lerises 

 of calcareos substrates in Hell Creek State Park to the 

 east, and could possibly occur in the potential RNA 



OVERALL BIODIVERSITT SIGNIFICANCE: 

 The Hell Creek uplands present a well-developed, 

 moderately extensive example of a productive, 

 widespread plant association of western wheatgrass - 

 green needlegrass grassland (Pascopyrum smithii - 

 Nasella viridula Herbaceous Vegetation) in excellent 

 condition. This area lies at the border between gentle 

 plains and Missouri Breaklands, and warrants 

 evaluation for its representation of both segments of 

 the Great Plains biome as well as the landscape 

 gradient. The habitat continuity with all of this 

 surrounding unglaciated terrain contributes to its 

 ecological value. 



Small cage exclosures were noted, and it is possible that 

 this area is already being used in studies of fire response 

 or wildlife utilization. If not, it would be worthwhile to 

 compile wildfire history information for use of this 

 otherwise well-suited area as a laboratory for studying 

 natural succession. Wildlife resources were not 

 evaluated. 



LAND USE: 



The area has been part of a grazing allotment as 

 secondary range. It is not currently grazed. Though it is 

 isolated, it receives use by hunters, if not other visitors. 



MANAGEMENT COMMENTS: 

 The area is notably free of yellow sweetclover (Meliiotus 

 officinalis). No exotic species management problems 

 were identified, though Japanese brome (Bromus 

 japonicus) is present at low levels in all communities 

 across this landscape 



Limber Pine Research Natural 

 Area 



environment: 



Limber Pine RNA encompasses 1,053 acres 

 representing a cross-section of Missouri River Breaks 

 habitat developed on residual soils weathered from 

 shales and non-calcareous sandstone mainly of the Fox 

 Hill Sandstone. It includes all of a large ravine system 

 incised to a maximum of about 300 feet, fed by small 

 springs, and emptying into the backwaters of Fort Peck 

 Reservoir. Extensive grasslands with scattered outcrops 

 span the upland benches and exposed ravine slopes. 



18 



