OVERGRAZING. 309 



The route followed by Bell from Manhattan to Salina, Fort Harker, and 

 Hays was retraced in 1918 for the express purpose of determining the relations 

 of the bluestems and buffalo grasses. Both buffalo grass and grama were 

 found on the ridges and upper slopes about Manhattan, though they were 

 secondary to the tall-grasses in importance. This relation continued west- 

 ward to the Dakota hills about Kanopolis, where the short-grasses became 

 more abundant, equaling the tall-grasses, and mixed or alternating with them. 

 This general condition continued to Hays, but with the short-grasses increas- 

 ing in abundance. Beyond Hays, they soon became controlling, though the 

 rough bluffs along the streams maintained their mixed cover. Throughout 

 the region from Kanopolis to Hays, overgrazed pastures exhibited a pure 

 short-grass cover, while protected or less grazed areas showed a mixture of 

 tall-grasses and short-grasses. It is clear that the short-grasses could not 

 have been replaced by the tall ones as a consequence of settlement, and then 

 have reentered the same areas under conditions of increasing cultivation. The 

 obvious explanation is that while they have been associated in the mixed 

 prairies for thousands of years, the tall-grasses were kept down by the buffalo 

 in the zone of concentration resulting from advancing settlement. They 

 reappeared with the going of the buffalo, and the disappearance of the buffalo 

 grasses was nothing more than their being overtopped by the bluestems 

 (plate 80). 



Drought periods doubtless played a part in the behavior of the bluestems 

 and buffalo gra ses, as they certainly did in the mixed prairies of Nebraska 

 and the Dakotas. In 1893 the gumbo plains north of the Niobrara River 

 were dominated chiefly by Bulhilis and Bouteloua gracilis, as a consequence of 

 excessive drought and overgrazing. In some places a pure cover of BuUrilis 

 stretched for many miles, almost unbroken by societies. This region has 

 been revisited several times from 1915 to 1918. The stretches of buffalo grass 

 and grama have disappeared, and in thei stead is a mixed prairie of Andro- 

 pogons, Agropyrum, and Stipa, below which is a more or less well-developed 

 layer of short-grasses. The drought of 1893-95 had a similar effect upon the 

 mixed prairies of western Nebraska, in which Stipa was the most conspicuous 

 dominant. This disappeared so completely, leaving a pure short-grass cover, 

 that it was regarded as a new grass invading for the first time when it re- 

 appeared in great quantity during the rainy years of 1897-98. Williams 

 (1898 : 54) has shown that dry periods have the same effect upon the appear- 

 ance of Agropyrum in the mixed prairies of the Dakotas. It was thought 

 that the tall-gra-sses might again disappear apparently during the drought 

 period of 1916-18, but this took place only in overgrazed pastures, showing 

 that overgrazing is an essential feature. 



Overgrazing cycles. The existence of cycles of overgrazing is beyond ques- 

 tion, and it is possible to recognize several kinds. The simplest and shortest 

 is brought about by such destructive overgrazing that the area will no longer 

 support the animals upon it. In the case of wild animals, such as the buffalo, 

 horse, etc., the herds sought a new range, while on restricted areas the cattle 

 died from starvation or were shipped out. In either event the grasses were 

 given an opportunity to regenerate, or in the worst cases the processes of 

 succession brought about a gradual return to the original conditions Such 

 overgrazing cycles correspond to the cycle of a subsere, and are relatively 



