532 Forestry Quarterly. 



ground for a short time during tlie winter, the minimum and 

 maximum temperatures being io° F. and 105° F. The to- 

 pography is a series of long, flat topped, gently sloping ridges, 

 rising with increasing steepness towards the summit of the moun- 

 tains and abruptly broken at intervals by deep river canyons. 

 Contrary to rule all arable land lies upon the ridge tops while the 

 narrow river canyons support but scattered trees and brush. 



The character of the second growth varies with the elevation. 

 At the lowest altitudinal limits of the type, or about 1,800 feet, 

 it occurs unmixed with other species. At higher levels Incense 

 Cedar, Douglas Fir, Sugar Pine and White Fir make their ap- 

 pearance. Above 3,200 feet pure pine is rarely met with except 

 upon south exposures. Dense thickets of Incense Cedar and 

 clumps of White Fir which were upon the ground at the time of 

 cutting, occupy the area excluding the more valuable species. Re- 

 production of pine becomes poorer and poorer ; brush is found in 

 ever increasing quantities ; and the region has the usual appear- 

 ance of heavily cut over areas. The influence, on the forest, of 

 these physical and artificial factors, is directly reflected in the 

 growth, which becomes progressively slower and slower as higher 

 elevations and less favorable sites are reached. Notwithstand- 

 ing the greater precipitation it is problematical whether the region 

 can be made as productive as at lower altitudes. 



The optimum development of pure second growth pine is 

 found at an elevation of 2,500 feet. Here it commonly occupies 

 the ground to the exclusion of other species with the exception 

 ■of Incense Cedar which forms an understory to the faster grow- 

 ing, but less tolerant pine. Stands are extremely dense, of ex- 

 ceptional height, and the narrow columnar top so characteristic 

 of Yellow Pine in virgin forests changes to a shorter more coni- 

 cal form. 



DIAMETER— HEIGHT TABLE 

 Second Growth Yellow Pine. Age 50 Years. 



