Native Grassland of Southwestern Iowa

摘要

Studies of the prairie by the writer and Fitzpatrick during 1922-33 were both extensive and intensive. They were extensive in that they included an area of 60,000 sq. mi. in western Iowa, eastern Nebraska and portions of the four adjoining states. They were intensive in that a record of the kinds and distribution of grasses, the abundance and relative importance of forbs, and other pertinent data were ascertained and recorded separately for each of 135 selected areas. Since most of these prairies were examined two or more times each growing season, and many repeatedly during a five-year period, a clear, concise description of each was secured. In this study it soon became clear that the vegetation receiving an annual rainfall of 30-32 in. was better developed in many ways than that in the drier areas westward and northward with 25-29 in. mean annual precipitation. Some of these differences were pointed out by Weaver avid Fitzpatrick (1932, 1934) but the prairie was considered in its entirety and space did not permit descriptions of individual prairies.