CONTENTS. 



IX 



PAGE. 



IV. Climax Formations of Western 

 North America — Continued. 



THE SIERRAN SUBALPINE FOREST. 



Pinus-Tsuga Association. 



Extent 226 



Groupings 227 



Factor and serai relations 228 



Societies. 



THE ALPINE MEADOW CLIMAX. 



Carex-Poa Formation. 



Nature 228 



Extent 229 



Unity 229 



Relationship and contacts 230 



Associations 231 



THE PETRAN ALPINE MEADOW. 



Carex-Poa Association. 



Extent 232 



Dominants. 



Groupings 232 



Factor and serai relations 233 



Societies. 



Vernal societies 234 



Estival societies 234 



THE SIERRAN ALPINE MEADOW. 



Carex-Agrostis Association. 

 Extent 234 



Dominants. 



Groupings 235 



Factor_and serai relations 235 



Societies. 



V. Agricultural Indicators. 

 General relations 237 



LAND CLASSIFICATION. 



Nature 237 



Relation to practices 238 



Proposed bases of classification 238 



The indicator method of land classification 240 



Use of climax indicators 240 



Soil indicators 241 



Shantz's results 242 



A SYSTEM OF LAND CLASSIFICATION. 



Bases 245 



Classification and use 245 



Methods 246 



V. Agricultural Indicators— Continued. 



CLIMATIC CYCLES. 



Nature 947 



The 1 1-year cycle \ 247 



Evidences 24s 



Periods of drought 250 



Recurrence of drought periods 251 



Significance of the sun-spot cycle 252 



Prediction of drought periods 253 



Utilization of cycles 254 



FARMING INDICATORS. 



Types of farming 255 



Relation of types of farming to indicators 255 

 Edaphic indicators of types of farming. . . 256 



CROP INDICATORS. 



Nature and kinds 257 



Climatic indicators of the types of crops. . 258 



Climatic indicators of kinds of crops 259 



Climatic indicators of varieties 259 



Life zones and crop zones 260 



Edaphic indicators of crops and methods . . 261 

 Indicators of native or ruderal forage 



crops 262 



AGRICULTURAL PRACTICE AND CLIMATIC 

 CYCLES. 



Cycles of production 262 



The excess-deficit balance 264 



Anticipation of cycles 266 



VI. Grazing Indicators. 

 Kinds of grazing 270 



GRAZING TYPES. 



Kinds of grazing indicators 271 



Significance of climax types 272 



Formations as indicators 273 



Associations as indicators 273 



Consociations as indicators 274 



Local grazing types 275 



Savannah as an indicator 276 



Kinds of savannah 278 



Savannah in relation to fire and grazing . . . 279 



Significance of serai types 279 



Prisere communities as indicators 280 



Subsere communities as indicators 282 



Fire indicators and grazing 283 



CARRYING CAPACITY. 



Nature and significance 284 



Determining factors 284 



Relation to communities and dominants. . 285 



Nutrition content 286 



Relation to climatic cycles 292 



Relation to rodents 293 



Relation to herd and management 293 



Measurement of carrying capacity 294 



Present and potential carrying capacity . . 295 



