Date of this Version
The great drought has now prevailed intermittently in the mid- west for a period of seven years. Damage to native vegetation in 1934 has been partially repaired, but further destruction has also occurred. Continued study of the shiftings in dominance among the grasses has revealed widespread losses of certain species and partial or complete replacement by others. Forbs also have greatly diminished, both in number of species and in abundance, and changes in structure of vegetation generally have been pronounced (3, 4). Hence it seemed advisable during 1939 to study the degree of deterioration of the grasslands, if any, from western Iowa, through eastern Nebraska and Kansas, to western Kansas where in places almost complete destruction of vegetation has occurred. This study included monthly determinations of water content of soil to the depth of root penetration of the grasses, and other major environmental factors characterizing the growing season. The rate of growth of vegetation and density of cover were determined, as well as the distribution of forbs.