the growing season; average climate patterns in Camp Crook, South 

 Dakota have peak monthy precipitation of almost 3 inches (7.6 cm) 

 in May and peak average monthly temperatures over 70 degrees F in 

 July (from Hansen and Hoffman 1987) . The 1993 growing season had 

 been a wet year. The 1994 growing season started as a typical year 

 in Carter County and a dry year in Harding County. Net 

 precipitation between January-June 1994 for Ekalaka was 8.66 inches 

 (22 cm) and for Camp Crook was 4.43 inches (11.25 cm; The Ekalaka 

 Eagle; Vol. 86, No. 27 of 8 July 1994). Rainfall during the summer 

 is mainly from thunderstorms and localized cloudbursts, typically 

 very light but sometimes accompanied by flash flooding. Storms may 

 also be accompanied by heavy hail and lightning strikes; seven 

 fires were ignited by lightening strikes in the Chalk Buttes in a 

 single storm on 1 July 1994 (The Ekalaka Eagle) , burning the 

 northernmost end of the Chalk Butte unit and spot fires elsewhere. 

 Lightening strikes occur each year on the District, with the 

 majority being less than 1 acre in extent (USDA Forest Service 

 1976) . Large areas of the Long Pines unit burned in the 1988 

 Brewer Fire. 



The District lies at the divide of watersheds for tributaries 

 draining into east-flowing rivers (Grand, Moreau and Powder) and a 

 north-flowing river, the Little Missouri. The District has no 

 perennial streams, but contains intermittent streams and numerous 

 springs throughout the areas, particularly at the contact between 

 the Ludlow member of the Fort Union Formation and overlying bedrock 

 which is more porous or fractured. Groundwater is the primary 

 water source for domestic and livestock use. 



The state line does not correspond with any major break in surface 

 features, but it does correspond with the boundaries of studies 

 conducted in Montana and South Dakota. A detailed biological 

 survey was made in Harding County shortly after the time of 

 settlement (Visher 1914) ; however, comparable stdies in the 

 adjoining Carter County were lacking. The study by Visher (1914) 

 provides a basis for addressing species 1 distribution and status, 

 as well as trend over the 80-year interval. 



Eight ecosystems as characterized by topographic position, slope, 

 rockiness and overall vegetation structure are described for 

 management planning by the U.S. Forest Service (197 6) in the study 

 area. A list is presented in the table on the next page. 

 Overall, the South Dakota units contain more extensive prairies and 

 the Montana units contain more woodlands. 



A preliminary vegetation classification of habitat types is 

 presented in Hansen et al. (1988), a classification which spans 

 three districts including Sioux District. Of the 27 forest, 

 woodland and steppe types which were described, nearly all occur on 

 the Sioux District with exception of types dominated by Festuca 

 idahoenis or Sarcobatus vermiculatus . Vegetation on the District 

 has not been mapped beyond the level of the ecological land units, 



