124 REDWOOD TYPE 



The climate is the controlling factor in the redwood's distri- 

 bution. It is only found where there is at least 30 inches of rain- 

 fall during the fall and winter and constant sea fogs during the 

 summer. This minimum precipitation is characteristic of the 

 southern part of its range where the trees do not reach as large 

 size as they do farther north. In fact the greater the rainfall the 

 better the trees, always provided the growing season is long. 

 This latter factor of temperature prevents the spread of the 

 species north. A mean annual temp>erature of 50 degrees or 

 60 degrees is necessary with not less than six months free from 

 frost. In other words, the climate is Hke that of the southeast 

 at Charleston, S. C, for example, in the absolute amount of 

 precipitation, and the range and duration of temperature, but 

 there are two marked differences. The great evaporation of the 

 southeast is checked by the summer fogs while there are no high 

 winds such as sweep our eastern coast in the fall and winter. 

 Hence the redwood grows under almost ideal conditions. There 

 is a long growing season to give large diameter and height growth 

 and enough moisture to not only further these but also permit of 

 a fair degree of density. 



These favorable climatic factors are still further enhanced by 

 favorable soil conditions. Situated on the lower slopes of the 

 coast .ranges there is sufficient depth of soil together with the 

 requisite drainage to prevent sourness. The most desirable soil 

 conditions are found on the flats along the streams. Here the 

 soil is fertile, deep and well watered and the redwood reaches a 

 diameter of 20 feet and the magnificent total height of 350 feet, 

 the tallest of all American tree species. With it are associated 

 hemlock and Sitka spruce but the redwood usually makes up at 

 least half of the total number of trees. The virgin stands per 

 acre in this flat subtype range from 150M board feet in the 

 northern part of its range to about a third of that in the south. 



The other subtype recognized by Fisher, the slope subtype, is 

 located on the relatively drier and more shallow slopes. With 

 less favorable conditions for redwood the competition from other 

 species is keener, such a large size is not attained and growth is 

 less rapid. The following table summarizing the principal facts 



