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The response of prairie vegetation of eastern Nebraska during the great drought of 1934 has been described (WVeaver, Stoddart, and Noll, '35). The purpose of the present study was to determine the results of the drought during the following year. The work has been extended to include the mixed prairie of west central Kansas. Studies in Tall-Grass Prairie The most severe drought ever recorded in the prairies of eastern Nebraska, western Iowa, and Kansas occurred during 1934. Studies of water content of soil throughout many growing seasons show clearly that the drought came on gradually during a period of 3 or 4 years. Water content of the upland was slowly depleted and by July 30, 1934, no water to a depth of 4 feet was available for growth. During July of this abnormally hot growing season, the average weekly maximum daily temperature varied from 980 to 1110 F. The average weekly minimum daily humidity varied from 15 to 22 per cent. During certain afternoons the humidity was only 3 to 5 per cent. Drought swept from hilltops down the slopes into mesic and hydric ravines. Wilting, drying, and death of vegetation were not due alone to high temperatures and low humidities but primarily to low water content of soil, since plants in watered areas thrived. Complete records of environmental factors in the prairie are being published elsewhere (Noll, '35) ; water content of soil available for growth before, during, and at the close of the drought are shown in figure 1. 1-ygroscopic coefficients of the Carrington silt loam, which ranged between 10.8 and 13.4 per cent at the several depths, were used as the approximate point of nonavailability. Samples from which the data were compiled were taken from a typical upland, little-bluestem prairie on a gentle south slope near Lincoln. The abundant water supply in early spring in the first 2 feet was greatly reduced during May and entirely depleted by midsum-imer. The moderate to

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Three plant communities near Hays, Kansas, showed considerable change in the composition of their dominant vegetation over the 30—year period from 1932 to 1961. The short grass community was dominated by Buchloe dactyloides and Bouteloua gracilis in 1932 and dominated only by Bouteloua gracilis in 1961. The little bluestem community was dominated by Andropogon scoparius during favorable years but by Bouteloua curtipendula and Bouteloua gracilis during drought years. The dominants of the little bluestem—big bluestem community were Andropogon scoparius and Andropogon gerardi in 1932 but by 1961 Andropogon gerardi was the only dominant. Two droughts periods, 1933—39 and 1952—56, were important in affecting these vegetation changes.