THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 



19 



only slightly greater than that of the conifer forest. The striking 

 and significant fact is that the seasonal range of temperature is far 

 less in the broad-sclerophyll region than in either conifer forest or 

 desert, the minima especially being decidedly above the others. 

 This fact fits well with Schimper's elucidation of the evergreen 

 habit as a means of utilizing short periods of favorable conditions for 

 activity at all times of the year. The relatively narrow seasonal 



Table 1. — Climate and vegetation. 



' The figures given here were worked out before the publication of the map (77). 

 of beginning and ending of summer season does not appreciably affect the results. 



The difference in date 



temperature range is of course due to the coastal location of the 

 great mass of the broad-sclerophyll region, and it is of interest that 

 all the other regions dominated by this type of vegetation are coastal 

 too. 



Summarizing briefly, we find that the broad-sclerophylls occur 

 abundantly in that part of western North America where the summer 

 precipitation is less than 20 per cent of the total, but that they 

 dominate only that portion of this area where the total precipitation 

 lies between 10 and 30 inches, and that the region of their dominance 

 is also characterized by very moderate temperature extremes. 



