Missouri River Bottomlands 

 Research Natural Area 



Note: Dillon Island and Grand Island were originally 

 recognized as separate research natural areas, but the 

 subsequent establishment of the Missouri River 

 Bottomlands RNA encompassed both islands and their 

 RNA boundaries. 



ENVIRONMENT: 



Missouri River Bottomlands Research Natural Area 

 encompasses about 9 miles of free-flowing Missouri 

 River and associated valleybottom spanning 5,085 

 acres, including three large islands. It also represents 

 the downstream end of the Missouri River designated 

 Wild and Scenic by the National Park Service (1976), 

 i.e., the 9 miles at the downstream end of a 149-mile 

 segment. The valleybottom is over '/z mile wide in the 

 area, with many vestiges of intact bottomland 

 vegetation on islands and meandered slivers scattered 

 among homesteads and abandoned cropland, 

 encompassed within the rugged Missouri River valley 

 rising sharply at the valley edges over 600 ft. above the 

 River. The RNA boundaries follow legal descriptions, 

 zigzagging along midslope or at least toeslope positions 

 almost continuously on both sides of the winding 

 valley. 



VEGETATION: 



The considerable relief, influence of water, and ongoing 

 successional processes accommodate a complexity of 

 vegetation. We have not tried in this case to place the 

 vegetation descriptions that follow by their relative 

 extent because they are nearly all between 5-10% of 

 the total landscape. Collectively, the plant associations 

 of black greasewood (Sarcobatus vevmiculatus) are 

 probably most extensive because they are prevalent in 

 lower valley slopes, as well as being a major bottomland 

 association. Stands of plains cottonwood (Populus 

 deltoides) of various successional stages are relatively 

 well-represented. Apart from the River itself, about 

 half of the RNA is made up of bottomlands, and in 

 each of the Bottomlands (named for the settlers: Hess, 

 Kendall, Knox, LeClair, McNulty), over half of the 

 bottomlands have been plowed. We have not tried to 

 characterize this major, albeit more altered, segment of 

 the landscape. 



The studies of Roberts and Sibbemsen (1979), which 

 focused on woodland and forest types, and Mackie 

 (1965), which emphasized rangelands, were the first 

 major efforts at describing and classifying vegetation for 



portions of the C. M. Russell National Wildlife Refuge, 

 and provide an important frame of reference. 



Artemisa cana I Pascopyrum smithii Shrubland 



[ARTCAN / PASSMI] 



silver sagebrush / western wheatgrass shrubland 



Shrub stands dominated by silver sagebrush (Artemisia 

 cana) are a recurrent bottomland landscape 

 component, occurring predominantly as small patches, 

 but ranging to large linear patches on river terraces as 

 well as the islands within the Missouri River. These 

 stands typically are developed on flat to very gently 

 rolling riverine and stream terraces, on medium- 

 textured (loam, silt loams, and silt) alluvial deposits. 

 Though this association can include stands with 

 wedand characteristics, as with temporarily flooded 

 hydrological regime and hydric soils, stands of the RNA 

 evidenced at most flooding and the vegetation was not 

 hydrophytic. Perched, or high water tables, may 

 irifluence the shrub rooting zone for a portion of the 

 year. Litter is the predominant ground cover, usually 

 in excess of 80 % cover, with small patches of bare soil 

 randomly distributed. This type grades to western 

 snowberry (Symphoricarpos occidenudis) on moister sites, 

 and Wood's rose (Rosa u/oodsii) or black greasewood 

 (Sarcobatus vermiculatus) dominated community, 

 sometimes directly to Wyoming big sagebrush 

 (Anemisia tridentata ssp. wyomingensis) or Sarcobatus 

 vermjculatus-dominated uplands that lack dominance 

 by rhizomatous grasses and have salt aff'ected soils. 

 These stands probably received heavy use by livestock 

 prior to RNA establishment. Most are in relatively good 

 condition but there are portions of these stands with a 

 strong non-native graminoid component. 



These Artemisia cana stands are like the big sagebrush 

 stands (Artemisia tridentata) elsewhere on the CMR 

 Refuge in that the percent shrub cover ranges from 

 mid-20s to lower-30s, the somewhat arbitrary cutoff 

 between shrubland and shrubby herbaceous vegetation. 

 Shrub dominance is almost exclusively contributed by 

 3-4 [5] feet tall Artemisia cana. Common rabbitbrush 

 (Chrysothamnus nauseosus), black greasewood 

 (Sarcobatus vermiculatus), and western snowberry 

 (Symphcxricarpos occideritahs) are nearly 100% constant, 

 but present in greater than trace amounts only at 

 ecotones to surrounding vegetation types. The 

 graminoid component is also consistent in composition 

 with western wheatgrass (Pascopyrum smithii), green 

 needlegrass (Nasella viridula), and PoajuncifoUa (alkali 

 bluegrass) . Despite sample stands being chosen for 

 appearing among the least disturbed, all stands have 

 some measure of non-native grasses including 



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