38 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Se«. 



may be determined with approximate accuracy without an 

 exhaustive study of the entire flora and fauna. The object 

 of the present paper is to make available a partial list of the 

 plants and vertebrate animals which may be depended upon 

 to establish the zonal identity of any locality within the State 

 of California, and so to make it possible for the inexperienced 

 person to "find himself" zonally, 



THE LIFE-ZONE CONCEPT 



Field biologists of the Pacific Coast are in general agree- 

 ment as to the value of the life-zone concept. It not only 

 fits in with well established facts but has direct practical appli- 

 cation in studies dealing with the ecology and geographic 

 distribution of plants and animals. That there are difficulties 

 in its application, and that there are numerous apparent in- 

 consistencies among life-zone workers, is readily admitted. 

 However, these will doubtless be cleared up as we come to a 

 more intensive study of environments and to a more careful 

 application of the fundamental laws of geographic distribu- 

 tion. In this connection it should perhaps be pointed out 

 that the life-zones as here accepted are not to be compared 

 with the mountain regions of Schimper (1898) and others, 

 nor even with the so-called life ''zones" or belts of some 

 workers in our own country. We here refer to those classi- 

 fications which are based largely upon altitude and latitude 

 and sometimes upon topography. Such zones or belts may 

 be somewhat useful in popular treatises, but are of slight 

 scientific value since their use entirely ignores the local con- 

 ditions which often greatly modify zonal position. 



The idea that life-zones are altitudinal or latitudinal is 

 correct only in a very general way or incidentally. They are, 

 instead, primarily biologic, that is, they are composed of and 

 detennined by a certain assemblage of plant and animal 

 species, and are affected by altitude or latitude only as these 

 modify the climate, more especially the temperature during 

 the critical periods of an organism's existence. This effect 

 of a change in latitude or altitude is sometimes overshadowed 

 by the influence of local conditions, resulting in the so-called 

 misplacement and spotting of zones. So frequent is this the 



