CONTENTS. 



II. 



HI. 



IV. 



Page. 



Introduction 6 



Relations of the chaparral to other 

 communities of scrub in North 



America 6 



Previous work 7 



Scope of present paper 9 



Acknowledgments 10 



Range and center of distribution .... 11 

 Location of greatest differentiation 



of type 12 



Location of dominance or great 



abundance of individuals 14 



Location of synthetic or closely re- 

 lated forms 14 



Location of maximum size of indi- 

 viduals 15 



Location of least dependence upon 



a restricted habitat 15 



Location of greatest importance 

 of the type in the climax commu- 

 nity 16 



Continuity and convergence of 



lines of dispersal 16 



Climatic relations 17 



The communities 20 



The broad-sclerophyll communities 20 

 The broad-sclerophyll forest for- 

 mation 21 



The chaparral formation 25 



The climax chaparral associa- 

 tion 26 



The conifer forest chaparral 



association 27 



Vegetation and habitat 30 



The locality for intensive study ... 30 



The Palo Alto region 30 



Jsisper Ridge 30 



The vegetation 32 



The habitat 42 



The soil factors 42 



Page. 

 IV. Vegetation and habitat — Cont'd. 



Physical character 42 



The soil moisture 43 



The soil temperature 55 



The atmospheric factors 56 



Light 66 



Temperature 67 



Wind 58 



The atmospheric moisture .... 58 



Discussion and correlations 63 



The broad-sclerophylls and their 



habitat 63 



The habitats of the two climaxes 



contrasted 67 



V. Development 72 



The climax regions of California . . 72 



The broad-sclerophyll climax forest 73 



The climax chaparral 75 



Evidence of its climax character 75 

 Extent of the chaparral as a true 



climax 76 



Successions leading to the chap- 

 arral climax 82 



Primary successions 82 



Secondary successions 86 



VI. Ecological character of the broad- 

 sclerophyll shrubs and trees .... 88 



Growth form 88 



Root system 89 



The leaf 92 



The deciduous element 92 



External characters 93 



Internal structure 97 



Effects of environmental condi- 

 tions upon leaf structure 107 



Comparative transpiration-rate. 110 

 Appendix: Annotated list of broad- 

 sclerophylls and accompanying spe- 

 cies 113 



Bibliography 122 



