trends provided further documentation of the fluctuations and 

 opportunity to relate recent conditions to those of the past. 

 From this perspective, the nature and range of fluctuations 

 observed during our study are consistent with, and fall 

 within, those of the past; periods of drought interspersed 

 with periods of high moisture are the rule. Overall, however, 

 the period 1930 to present has been one of relative drought 

 matched only by a period from about 1625 to 1685. 



Vegetation 



The varied topography and soils support a complex mosaic 

 of vegetation. Mackie (1970) recognized 8 major 

 vegetation/habitat types comprising 12 communities 

 (associations or associes) occurring on uplands. Two 

 additional types characterized bottom- lands along the 

 Missouri River. Our classification (Table 3.1) was similar 

 with respect to major types, described herein as 

 vegetation-physiographic types, but we also delineated "cover 

 types" based on degree of overhead cover and fire history in 

 forested habitats. This approach describes communities in 

 terms of existing vegetational characteristics and serai stage 

 rather than potential or climax vegetation. 



Forested types covered approximately 51% of the area, and 

 generally occurred as scattered, open, and medium-density 

 stands of coniferous trees and shrubs along side-slopes of 

 drainages (Table 3.1). Dense stands, characterized by almost 

 continuous contact between individual tree canopies of 

 relatively small (narrow) and similar size, did not occur. 

 Medium density stands were those in which almost all canopies 

 were in contact and the individual tree canopies were 

 relatively large but included a variety of sizes. Open stands 

 held trees of sufficient density to provide frequent contact 

 between canopies, but also contained numerous openings. 

 Scattered stands were those in which individual trees were 

 widely separated with few if any canopies in contact. 

 Riparian forest, dominated by deciduous trees and shrubs, was 

 restricted to Missouri River bottomlands (2.5% of the area). 



Low shrub and grass dominated communities covered 49% of 

 the area, including all ridgetops, coulee bottoms, benches, 

 and some steep, south-facing slopes. Extensive interspersion 

 of forest and open types provides a general savannah-like 

 aspect to the vegetation (Figs. 3.3 and 3.4). This aspect is 

 accentuated by the prevalence of scattered and open cover 

 types in forested communities (Table 3.1) and the generally 

 low stature of coniferous trees, which rarely exceed 15 m in 

 height. 



Detailed descriptions of the major vegetation/habitat 

 types on the study area are provided by Mackie (1970). The 



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