Page:Plant indicators the relation of plant communities to process and practice.djvu/15

CONTENTS.

IX

PAGE.

IV. Climax Formations of Western North America Continued.

Pinus-Tsuga Association

 * Extent 226


 * Groupings 227


 * Factor and serai relations 228

Carex-Poa Formation

 * Nature 228


 * Extent 229


 * Unity 229


 * Relationship and contacts 230


 * Associations 231

Carex-Poa Association

 * Extent 232


 * Dominants.


 * Groupings 232


 * Factor and seral relations 233

Societies

 * Vernal societies 234


 * Estival societies 234

Carex-Agrostis Association

 * Extent 234

Dominants

 * Groupings 235


 * Factor and seral relations 235

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

Climatic Cycles

 * Nature 247


 * The 11-year cycle 247


 * Evidences 248


 * 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

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 seral 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