ILLUSTRATIONS. 



XV 



PAGE. 



Plate 74. 



A. Aristida purpurea and divaricata in- 



dicating moderate overgrazing on 

 Bulbilis plains, Texhoma, Okla- 

 homa 298 



B. An annual, Lepidium alyssoides, indi- 



cating complete overgrazing in a 

 pasture, Fountain, Colorado .... 298 

 Plate 75. 



A. Grindelia indicating overgrazing in 



original Stipa bunch-grass prairie, 

 Williams, California 300 



B. Vernonia indicating overgrazing in 



short-grass plains, Stratford, 



Texas 300 



Plate 76. 



A. Gutierrezia and Aristida in short- 



grass plains, Albuquerque, New 

 Mexico 300 



B. Yucca and Aristida in mixed prairie, 



Hays, Kansas 300 



Plate 77. 



A. Opuntia polyacantha indicating over- 



grazing in mixed prairie, Guern- 

 sey, Colorado 302 



B. Prosopis and Calliandra indicating 



overgrazing in desert plains, Santa 

 Rita Reserve, Tucson, Arizona. 302 

 Plate 78. 



A. A summer annual, Euphorbia mar- 



ginata, indicating complete over- 

 grazing in a pasture, Fountain, 

 Colorado 304 



B. A winter annual, Eschscholtzia mexi- 



cana, indicating both overgrazing 

 of grassespand ^grazing capacity, 

 Santa Rita Reserve, Tucson, 



Arizona 304 



Plate 79. 



A. Stipa setigera indicating the original 



bunch-grass prairie, Fresno, Cali- 

 fornia 306 



B. Avena fatua on bunch-grass land, 



Rose Canyon, San Diego, Cali- 

 fornia 306 



C. Festuca myurus and Bromus hordea- 



ceus on bunch-grass land, Corn- 

 ing, California 306 



Plate 80. 



A. Mixed prairie of Andropogon-Boutc- 



loua racemosa and Bulbilis-Bou- 

 teloua gracilis, Wilson, Kansas. . 308 



B. The same prairie in an overgrazed 



pasture, showing pure short-grass 



sod, Wilson, Kansas 308 



Plate 81. 



A. Isolation transect in Stipa-Bouteloua 



pasture, Mandan, North Dakota. 314 



B. Isolation transect in Agropyrum-Bul- 



bilis pasture, Ardmore, South 

 Dakota 314 



page. 

 Plate 82. 



A. Rodent exclosure, showing combined 



effect of cattle and rodents on the 

 crop of winter annuals, chiefly 

 poppy (Eschscholtzia mexicana), 

 Santa Rita Reserve 316 



B. Difference in yield of poppies in ro- 



dent exclosure, cattle exclosure, 

 and pasture, Santa Rita Reserve. 316 

 Plate 83. 



A. Wheat-grass (Agropyrum glaucum) 



following sagebrush after clear- 

 ing, Brookings, Oregon 320 



B. Bunch-grass (Agropyrum spicatum) 



following fire in sagebrush, Boise, 



Idaho 320 



Plate 84. 



A. Mixed grazing type of oak chaparral 



and grass, Sonora Grazing Sta- 

 tion, Edwards Plateau, Texas . . 326 



B. Mixed type of tall-grass (Agropyrum) 



and short-grass (Bulbilis-Boute- 

 loua) with relicts of Sarcobatus, 

 Ardmore Station, South Dakota. 326 

 Plate 85. 



A. Park of Nolina and grass in oak chap- 



arral, Sonora Grazing Station, 

 Edwards Plateau, Texas 328 



B. Yucca radiosa in desert plains, Em- 



pire Valley, Elgin, Arizona 328 



Plate 86. 



A. Climax subalpine forest of Abies and 



Pinus as a climatic indicator, 

 Yosemite National Forest, Cali- 

 fornia 336 



B. Consocies of Rudbeckia occidentalis 



as an edaphic indicator of clearing 

 and fire, Utah Experiment Sta- 

 tion, Ephraim 336 



Plate 87. 



A. Chamaebatia foliolosa indicating fire 



in pine forest, Yosemite National 

 Park, California 354 



B. Ceanothus velutinus indicating fire in 



pine forest, Burns, Oregon 354 



Plate 88. 



A. Anaphalis and Epilobium indicating 



a recent burn, Wind River Ex- 

 periment Station, Washington. . 354 



B. Pteris and Rubus indicating fire fol- 



lowing one marked by Arbutus, 

 Prunus, etc., Pseudotsuga forest, 



Eugene, Oregon 354 



Plate 89. 



A. Pine reproduction in a fenced area, 



Fort Valley Experiment Station, 

 Arizona 356 



B. Fenced quadrat showing effect of 



grazing upon reproduction, Cliffs, 

 Arizona 356 



