CONTENTS. 



VII 



PAGE. 



IV. Climax Formations of Westebn 

 North America — Continued. 



THE SHORT-GRASS PLAINS. 



BuUnlis-Bouteloua Association. 



Nature 139 



Range 140 



Grouping of dominants 141 



Factor relations 142 



Sequence of dominants 142 



Societies. 



Prevernal societies 143 



Vernal societies 143 



Estival societies 143 



Serotinal societies 144 



Clans. 



Prevernal clans 144 



Vernal clans 144 



Estival clans 144 



Serotinal clans 144 



THE DESERT PLAINS. 



Aristida-Bouteloua Association. 



Nature 144 



Range 145 



Rank of dominants 146 



Grouping of dominants 146 



Sequence of dominants 147 



Societies. 



Vernal societies 148 



Estival societies 148 



Serotinal societies 149 



Clans. 



THE BUNCH-GRASS PRAIRIE. 



Agropyrum-Stipa Association. 



Nature 149 



Range 149 



Factor relations and sequence 151 



Societies. 



Prevernal societies 152 



Vernal societies 152 



Estival societies 152 



Serotinal societies 152 



Clans. 



Prevernal clans 152 



Vernal clans 152 



Estival clans 152 



Serotinal clans 152 



THE SAGEBRUSH CLIMAX. 



Atriplex- Artemisia Formation. 



Nature 152 



Unity of the formation 153 



Range 154 



Subclimax sagebrush 155 



Associations 156 



PAGE. 



IV. Climax Formations of Western 

 North America — Continued. 



THE BASIN SAGEBRUSH. 



Atriplex- Artemisia Association. 



Range 156 



Rank and grouping 157 



Correlations 158 



Successional sequence 159 



Societies. 



Grass communities appearing as societies . 160 



Vernal societies 160 



Estival societies 160 



Serotinal societies 160 



THE COASTAL SAGEBRUSH. 



Salvia- Artemisia Association. 

 Range 160 



THE DESERT SCRUB CLIMAX. 



Larrea-Prosopis Formation. 



Nature 162 



Range 163 



Unity of the formation 163 



Structure of the formation 165 



Summary of Dominants. 



Associations 166 



Relation to other formations 167 



THE EASTERN DESERT SCRUB. 



Larrea-Flourensia Association. 



Correlations and sequence 168 



Societies. 



THE WESTERN DE8EBT SCRUB. 



Larrea-Franseria Association. 



Nature 170 



Extent 171 



Structure 172 



Groupings 172 



Factor relations 173 



Successional relations 174 



Root relations 175 



Societies and Clans. 



THE CHAPARRAL CLIMAX. 



Quercus-Ceanothus Formation. 



Nature 177 



Unity of the chaparral formation 178 



Climatic relations 178 



Origin and succession 179 



Range and extent 180 



Structure of the formation 181 



Grouping of dominants 181 



Associations 183 



THE PETRAN CHAPARRAL. 



Cercocarpus-Quercus Association. 



Nature and extent 183 



Contacts 184 



Groupings 185 



Equivalence of dominants 186 



