ECOLOGY. 341 



of great value, an intensive study qf grazing indicators has been 

 begun by means of special fenced inclosures in the various grassland 

 associations. These inclosure fences are adjusted annually in such a 

 way as to show the cumulative effects of grazing and the influence of 

 each year of the climatic cycle. The enormous importance of cUmatic 

 cycles for agriculture, grazing, and forestry makes cycle indicators 

 matters of the greatest concern, and an especial endeavor is being made 

 to work out an effective system. 



Grazing Research, hy F. E. Clements, Edith Clements, and G. V. Loftfield. 



A comprehensive investigation of grazing has been carried on 

 throughout the year, part of it independently and part in coopera- 

 tion with State and National agencies. Informal cooperative arrange- 

 ments of various kinds have been made with many of the State experi- 

 ment stations, and the majority of these have again been visited for 

 conferences. The cooperation with the Forest Service, Biological 

 Survey, and the University of Arizona in the inclosure study of rodent 

 damage and carrying capacity has been especially profitable. Timely 

 winter rains on the Santa Rita Range Reserve produced a remarkable 

 development of winter annuals, predominantly poppy, Eschscholtzia 

 mexicana, but with much Lupinus sparsiflorus, Malacothrix fendleri, 

 and others. The various inclosures and exclosures graphically revealed 

 the effects of fencing out cattle, and cattle and rodents. The abund- 

 ance, branching, height, number of flowers, etc., for the important 

 forage annuals were much greater in the cattle inclosures than in the 

 pastures, and somewhat greater in the cattle-rodent exclosures than in 

 the cattle exclosures alone. In fact, such annuals as Lupinus and 

 Malacothrix were practically eliminated in the pastures. Summer 

 rains likewise brought about the first luxuriant development of grasses 

 for three years, and similarly striking results were obtained in the 

 various fenced areas. 



The grass quadrats were charted for the first time since their installa- 

 tion, as the perennial grasses had made practically no growth the pre- 

 ceding summer. Others were located, and the growth was cut at the 

 grazing level to determine the total amount of forage produced' in the 

 endeavor to correlate forage production and the carrying capacity 

 with the wet and dry phases of the climatic cycle. The food habits of 

 the kangaroo rat have been studied intensively, and it has been found 

 that they do most serious damage to the range during the dry phase 

 of the cycle. During wet years the damage done is considerable, as is 

 shown by the large quantities of Bouteloua spikes stored in the burrows, 

 but the failure of the grasses to develop spikes in 1918 resulted in the 

 storage of enormous numbers of grass crowns and the complete denuda- 

 tion of considerable areas. 



