dominated the site. There is major overlap with 

 BOUGRA in a grass composition that is often 

 associated with xeric or disturbed conditions, including 

 plains muhly (MiMenbergia cuspidaia) , Sandberg's 

 bluegrass (Poa secunda), and tumblegrass {Schedormadus 

 paniculatus) , and the absence of green needlegrass 

 (hlasella viridula). 



This communitymay represent a transition state 

 between Bouteloua gracilis grassland making up the core 

 of the colony and the colony perimeter. The difference 

 between this outer zone and the inner core may reflect 

 shorter occupancy and duration of succession. 

 Alternately, it may represent the greater speed of 

 recovery in this zone. The plot has the same level of 

 gravels exposed at the surface as the preceding, but it 

 does not have the "pedastalling" of wind erosion 

 around the base of each piece of gravel. It is also in a 

 position for speedier recolonization with the growth of 

 rhizomes by Pascopyrum smithii from directly adjoining 

 areas. [Plot NHMTECRN98SC0016] 



Artemisia tridentata ssp. wyomingensis I Pascop/yrum 



smithii - Nasella viridula Shrubland 



[ARTTSW / PASSMI - NASVIR] 



Wyoming big sagebrush / western wheatgrass - greeen 



needlegrass shrubland 



This association or the very siinilar ARTTSW / 

 PASSMI, which lacks green needlegrass (hlasella 

 viridula) , commonly exist as matrix or large patch types 

 associated with gently rolling benchland. This 

 particular example of the type is a remaining fragment 

 outside of the discrete prairie dog colony, dominated by 

 Wyoming big sagebrush (Artemisia tridentata ssp. 

 vryamirxgensis) and western wheatgrass (Pascopyrum 

 smithii). It also has blue grama (Bouteloua gracilis) 

 present; the importance of the grass species in this 

 association are nearly the opposite of what was 

 recorded for the preceding association. 



The site occurs at 2,980 ft elevation at the head of a 

 draw in a slight swale that may receive additional 

 moisture through snow deposition, ostensibly causing 

 Nasella viridula to be present. The herbaceous layer is 

 dominated by Pascopyron smithii and has Nasella viridula 

 as a subordinate, up to 10% cover. Canopy cover of the 

 grazing-sensitive Nasella viridula is highly variable in 

 these communiries depending on past grazing 

 intensities and it is used as an indicator species at even 

 reduced cover values. This is a producrive shrubland 

 that has less than 50% bare substrate (soil and gravel) , 

 the ground cover consisting mostly of litter, basal area, 

 mosses and lichens. Total shrub cover (25%) places this 



stand at the break point between shrubland and 

 herbaceous vegetation. The subshrubs fringed sage 

 (Artemisia frigida) and broom snakeweed (Gutierrezia 

 sarothrae) are coiwistently present in barely greater than 

 trace amounts. The usual complement of forbs 

 including scarlet globemallow (Sphaeralcea coccinea) , 

 prairie aster (Aster falcatus) , and fleabane (Erigeron 

 purrulis) are present in trace amounts; only field 

 milkvetch (Astragalus agrestis) exceeds trace amounts. 

 [Plot NHMTECRN98SC0015] 



Other Vegetarion Types: Side slopes were not sampled, 

 and the highly dissected terrain overlain by recent fire 

 contributed to a grassland mosaic. Areas of localized 

 dominance by plains muhly (Muhler)bergia cuspidata) 

 were noted, along with Ponderosa pine / bluebunch 

 wheatgrass (Pinus ponderosa I Pseudoroegr^ria spicata) 

 where pine survived the recent bum. 



OVERALL BIODIVERSITY SIGNIFICANCE: 

 Like the Prairie Dog Island RNA, this site could be 

 used to track plant succession in the wake of prairie 

 dog use, and/or be considered for prairie dog 

 reintroduction. It is the orUy one of the two sites that 

 has retained a dominance of narive species, making it 

 better suited in studying natural succession. 



Apart from such natural succession, this RNA does not 

 represent biome features but has the potential. It lies 

 between rolling glaciated plains and south-facing 

 breakland topography. It is the only RNA with intact 

 plant associarions on glacial deposits as opposed to 

 lacustrine or aeolian deposits, or unglaciated 

 landscapes. 



Mountain plovers were previously documented in the 

 RNA, and the presence of burrowing owls was 

 mentioned in the original establishment record. 

 Wildlife values were not evaluated in this study. 



LAND USE: 



The history of livestock use is evidenced in the site 

 name, a gathering point for southward cattle drives or 

 to disperse cows going north (Haglan pers. commun.) 

 The site is currently part of a large allotment. 



MANAGEMENT COMMENTS: 

 A fire had burned at the south end within the recent 

 years. It appeared to have originated in the Rock Creek 

 valley, below, burning more of the surrounding slopes 

 than the uplands. There were no noxious weed 

 problems or exotic species invasions noted. 



23 



