Manning Corral Prairie Dog 

 Town Research Natural Area 



environment: 



Manning Corral Prairie Dog Town Research Natural 

 Area encompasses a flat ridge, essentially a strip of 

 tableland at the edge of breakland topography. It is 

 typical of the Montana Glaciated Plains (Subsection d) 

 of the Northwestern Glaciated Plains Section (33 ID). 

 Such areas have received Conrinental glaciation and 

 accompanying deposits of till and drift over what is 

 essentially a planar to gently undulating surface of soils 

 developed from predominantly clay shales and siltstone. 

 There are numerous on-site exposures of glacial drift to 

 indicate this area has been glaciated. It adjoins and is 

 actually mis-mapped within the Missouri River Breaks 

 (Subsection f) of 33 ID (Nesser et al. 1997); areas that 

 are strongly and deeply dissected terrain. West of the 

 RNA the elevation drops 600 feet to Rock Creek and 

 east of the RNA are the convoluted subdrainages of 

 Seven Mile Creek). There are bedrock outcrops to the 

 immediate west below the tableland to indicate that 

 the overlying glacial deposits are a thin veneer. The 

 climate (nearest station Haxby 18 SW) verges on 

 Continental with cold, dry winters and the peak in 

 precipitation comes in May and June (36% of the year's 

 total). 



VEGETATION: 



The diversity of communities present corresponds in 

 part with the use patterns of the black-tailed prairie dog 

 (Cynomys ludovicianus) colony that died in a 1993 

 sylvatic plague episode five years earlier. The present 

 landscape is in a state of secondary succession. Three 

 areas were sampled that appeared to have 

 approximately the same environmental parameters but 

 that may represent different successional stages. 



The RNA may have supported shrub-dominated 

 communities of Wyoming big agebrush / western 

 wheatgrass - green needlegrass (Artemisia tridentam ssp. 

 wyomingemis I Pascopyrum smithii) with or without a 

 major component of green needlegrass (Nasella 

 \dridula) . However, no traces of sagebrush skeletons 

 were found in the area occupied by the dog town. 

 Normally in these dry environments the woody 

 skeletons can persist scores of years if they are not 

 burned, even if only in dished-out rootcrowns. We did 

 not see evidence that they had decomposed or burned. 

 In glaciated terrain of northcentral Montana, such 

 sagebrush-dominated communities general decline 

 away from broken topography and with well-drained 



soils. Information from the surroundings was 

 inadequate to examine cause and effect. 



Boutdoua gracilis Herbaceous Vegetation 



[BOUGRA] 



blue grama grassland 



Across the formerly occupied prairie dog town is a 

 shortgrass prairie vegetation that covers most of the 

 gentle uplands of the designated area. This prevailing 

 vegetation is dominated by blue grama (Bouteloua 

 gracilis) but with discrete patchy islands where most of 

 the individual plants of midgrass-height species are 

 concentrated around individual prairie dog burrows. 

 This community type appears to be developed in the 

 identical setting as the two types described below. It is 

 distinguished from them by the severe reduction of 

 western wheatgrass (Pascopyrum smit/ui) cover, the 

 absence of Wyoming big sagebrush (Artemisia trideraata 

 ssp. wyomingensis) , and the major increase of 

 tumblegrass (Schedonnardus paniculatus) . It is further 

 distinguished by the presence of early succession species 

 like lemon scurf-pea (Psoralea lanceolata) and conyza 

 (or horseweed; Conyza canadensis). 



This association has very low vegetative cover, low 

 levels of litter accumulation, and much of the ground 

 surface made up of exposed gravels. We hypothesized 

 that these conditions were created when prairie dogs 

 occupied the site and the resulting cover removal 

 promoted wind deflation of the soil surface. Thus this 

 site has three times more exposed gravels than the 

 adjacent shrub-dominated site outside of the prairie 

 dog colony, as well as much higher cover of moss and 

 lichens. 

 [Plot NHMTECRN98SC0017] 



Pascopyron smithii - Bouteloua gracilis - Carex fiUfoUa 



Herbaceous Vegetation 



[PASSMI - BOUGRA - CARRL) 



western wheatgrass - blue grama - threadleaf sedge 



At the fringes of the formerly occupied prairie dog town 

 there is an abrupt transition between a sagebrush- 

 dominated commuiuty outside the colony perimeter, 

 and a grass-dominated community within the colony. A 

 pair of adjoining plots were sampled for direct 

 comparison. Graminoids dominate the site; blue grama 

 (Bouteloua gracHis) and western wheatgrass (Pascopyrum 

 smithii) are the most conspicuous. Trace amounts of 

 shrubs were noted, including Wyoming big sagebrush 

 (Aremisia tridentata ssp. wyomingensis), but there are no 

 shrub skeletons to indicate that this lifeform previously 



22 



