XVI 



ILLUSTRATIONS. 



PAGE. 



Plate 90. 



A. Reproduction cycle of Picea engel- 



manni, Uncompahgre Plateau, 

 Colorado 358 



B. Extension of Juniperus into sage- 



brush during wet phase of cycle, 



Milford, Utah 358 



Plate 91. 



A. Arbutus indicator of reforestation 

 sites, Pseudotsuga f orest.Eugene, 

 Oregon 360 



PAGE. 



Plate 91 — Continued. 



B. Reproduction of Pseudotsuga from 

 seed stored in soil, Wind River 

 Experiment Station, Washington. 360 



Plate 92. 



A. Salix and Ceanothus indicating plant- 



ing site in sandhills, Halsey, Ne- 

 braska 362 



B. Three-year-old plantation of jack 



pine (Pinus divaricata) in sand- 

 hills, Halsey, Nebraska 362 



C. Jack pines 10 years after transplant- 



ing, Halsey, Nebraska 362 



TEXT-FIGURES. 



PAGE. 



1. Zones of a fairy ring due to Agaricus 



tabularis : A and C, during a moist 

 period; B, during a dry period. . . 11 



2. Diagram of the climax and serai com- 



munities of the formation 73 



3. Monthly and total rainfall in the 



grassland climax 117 



4. Map showing the percentage of annual 



precipitation between April 1 and 

 September 30 119 



5. Monthly and total rainfall in the 



Basin sagebrush association 153 



6. Monthly and total rainfall in the desert 



scrub climax 164 



7. Monthly and total rainfall in the 



chaparral climax 179 



8. Monthly and total rainfall in the 



woodland climax 195 



9. Monthly and total rainfall in the 



montane forest 206 



10. Monthly and total rainfall in the 



Coastal forest 215 



11. Monthly and total rainfall in the 



Petran subalpine forest 223 



12. Monthly and total rainfall for the 



alpine meadow climax, summit 



of Pike's Peak, 14,100 feet 233 



13. The 11-year cycle during the last 250 



years, as shown by the yellow 

 pine and Sequoia 248 



PAGE. 



14. Double and triple sun-spot cycle in 



yellow pine from 1700 to 1900 



A. D 250 



15. 2-year cycle in a sequoia 263 



16. Graph of total and seasonal rainfall at 



Williston, North Dakota 264 



17. Graph of total and seasonal rainfall at 



Cheyenne, Wyoming 265 



18. Graph of total and seasonal rainfall at 



Akron, Colorado 266 



19. Graph of total and seasonal rainfall at 



Amarillo, Texas 267 



20. Cycles of rainfall in the Ohio Valley, 



and in Illinois 269 



21. Cycles in the yield of corn and in the 



rainfall of its critical period of 

 growth 269 



22. Pastures for the intensive study of 



carrying capacity and rotation 

 grazing, Mandan, North Dakota. 313 



23. Isolation transect for measuring cyclic 



changes in yield under protection 

 and under grazing 314 



24. Arrangement of corrals, sheds and 



scales, Mandan, North Dakota. . 315 



25. Indicators of planting sites in the vari- 



ous zones, Utah Experiment Sta- 

 tion, Ephraim 361 



