Date of this Version
The long period of desiccation, which began in 1934, finally terminated in 1940. The western portion of True Prairie was greatly decimated and a veritable mosaic of types of vegetation resulted. These ranged from well-preserved relict communities of bluestems (Andropogon) to mixed stands of grasses on nearly bared soil, but included communities of western wheat grass (Agropyron smithii) , short grasses (Bouteloua gracilis and Buchloe dactyloides) , needle grass (Stipa spartea), and prairie drop seed (Sporobolus heterolepis) . These types varied in size from a few square rods to many acres (fig. 1). One 15- acre prairie, which was mapped in detail, revealed five types, each of which was dominated by a single species, and eight mixed types where two species in each were in definite control. Some of these types of vegetation, moreover, recurred in several parts of this prairie.
Over the entire western margin of True Prairie, wide areas of soil were often still open to invaders in 1940 and others were populated only thinly by individuals of a potential grassland type. Even the vegetation in relict communities had usually been greatly thinned by the drought, and dynamic development involved in mutual invasions, competition, and reaction was pronounced (fig. 2). In this process of revegetation western wheat grass played an important part.