OVERGRAZING. 307 



striking similarity in the appearance of the range in former times and at pre- 

 sent. So far as the numerous statements which have been consulted indicate, 

 the general appearance and conditions of the range country have changed 

 but little since the time when they were first explored by white men. " (45) 



Succession and cycles. The range studies of the past six years have fur- 

 nished a complete explanation of the sharp difference in views as to the past 

 conditions of overgrazing. There is no question that Smith, Wilcox, and others 

 are correct in stating that there has been no essential permanent change in the 

 composition and structure of the great grassland associations. On the other 

 hand, it is equally certain that there have been great local or temporary 

 changes, which critically reduced the carrying capacity, or actually destroyed 

 the climax community. A broad view of the grassland climax would warrant 

 the opinion that it had never undergone serious change, while the observation 

 of a particular range would justify the statement that the original grasses 

 were completely destroyed. This apparent contradiction is readily explained 

 by the student of succession, as is likewise the fact that one observer may 

 find good grass in the same locality where another had seen a barren waste. 

 It is obvious that an area destructively overgrazed would be abandoned by 

 grazing animals for an untouched portion of the same climax, and that the 

 bare area would then pass through the various stages of succession to again 

 reach the climax in 20 to 30 years. This is recognized by Wilcox (31) in 

 connection with the overgrazing caused by buffalo: 



"These accounts indicate what would naturally be expected, viz, that 

 where buffaloes congregated in immense herds the grass was totally destroyed 

 for the time and the ground was much cut up or packed down, according as 

 dry or wet weather prevailed. The result of such accumulations of large 

 herds was the apparent total destruction of the grass. It should be remem- 

 bered, however, despite the fact of apparent total destruction wrought by the 

 buffalo along the Une of their migration and during their close association at 

 breeding seasons, the range recovered so that the evidence of their destructive 

 grazing was entirely lost within a few years. This fact indicates also the 

 possibility of range improvement at present." 



While great variations in the condition of the range can be explained by 

 local overgrazing and subsequent recovery as a consequence of succession, 

 further explanation can be found in the action of climatic cycles. The chief 

 effect of the dry phase of the cycle was found in the impetus given to over- 

 grazing, while the wet phase favored successional processes and hastened 

 recovery. Climatic changes also serve to explain many of the contradictory 

 statements as to the same locaUty. Even under ordinary conditions of graz- 

 ing, the same area would be strikingly different during a drought period and 

 the preceding or foUowmg wet phase. If it were visited at a time when 

 drought and overgrazing coincided, and then at one in which more or less 

 complete recovery were followed by a wet period, no greater contrast could 

 be imagined. Moreover, while the effects of overgrazing were usually local, 

 those of drought j)eriods were general for the most part, and hence climatic 

 cycles are especially important in furnishing the explanation of the discordant 

 statements of explorers. The effect of drought in changing the dominants 

 of the range is illustrated by the grassland south of the Niobrara River. In 

 1893, this was dominated by Aristida purpurea and A. basiramea as a result 

 of drought and overgrazing, while by 1915 the awn-grasses had been com- 



