FIG. 9 3 Forest-edge at Wil 

 and herbs in foreground, bri 



am Trelease Woods, University of Illinois 

 rs and shrubs in nniddle, forest in backgr 



meter destroyed enough forage on three acres during 

 one month to support one cow for a month ( Stoddart 

 and Smith 1943). 



Rodents and rabbits consume very considerable 

 amounts of grasses and other herbs and cause great 

 damage at times of high populations. In a study per- 

 formed in Arizona (Taylor 1930), grazing by 

 Gunnison's prairie dogs alone consumed 87 per cent 

 of the total grass production and grazing by cattle 

 and rodents combined, 95 per cent. In California, 

 Beechey's ground squirrels eliminated 35 per cent of 

 the green forage by the end of the season, pocket 

 gophers 25 per cent, and kangaroo rats 16 per cent 



(Fitch and Bentley 1949). Since these various 

 rodents have food preferences of grass species simi- 

 lar to those of cattle, there is obviously severe com- 

 petition between them, especially in times of drought. 

 When rodents are not overly abundant, they have 

 some beneficial effects in fertilizing, aerating, and 

 mixing the soil. 



Among big-game mammals, bison and wapiti are 

 largely grass-eaters, especially during the summer 

 season. Food consumption of bison is about equal to 

 that of cattle, but wapiti eat only about half as much 

 per individual. In Yellowstone Park it has been esti- 

 mated that wapiti may utilize 67 per cent of the avail- 



TABLE 9-5 Carrying capacity of 



grasslands for big game and livestock (fr. 



sources, compiled by Petrides 1956). 



Location 



Game or livestock 



Number/mi* Biomass/mi 

 (2.6 km^) Pounds Kg 



Oregon 



Tanganyilca, Africa 



Montana 



Arizona 



Western U.S. 



Western U.S. 



Nairobi Nat. Pk., Africa 



Nairobi Nat. Pk., Africa 



Antelope (64%), mule deer (36%) 9 1,000 454 



Bush country game 10 3,300 1,498 



Bison (50%), mule deer, elk, bighorn 21 14,000 6,356 



Bison 17 17,000 7,718 



Cattle, ave. all grassland types 20 20,000 9,080 



Cattle, tall grass prairie 28 28,000 12,712 



(1) herbivorous big game 85 28,000 12,712 



(2) herbivorous big game 134 47,700 21,656 



Grassland, forests, and forest-edges 1 27 



