774 



AMERICAN FORESTRY 



Chaparral, Spruce, Bull Pine and Sugar Pine 



forest distribution as influenced by slope ant) exposure in the sierra madre range in southern cali- 

 fornia, chaparral on the dry south slopes, bull pine, sugar pine and spruce on the west slopes, 

 ridges and cool ravines. the abrupt transition from forest to chaparral on the ridge summits 

 is seen from many' ro.'^ds and tralls running up into the mountains from san bernardino .\nd 



PASADEN.\ 



driven them and made them fitted. 

 On some of the flattened Sierra ridge 

 summits or rocky slopes scanty tree 

 growth is maintained on almost bare 

 rock, the disintegrated granite or rock 

 crevices giving support to foxtail, lodge- 

 pole and even yellow pine. Only trees 

 of great hardiness can withstand these 

 conditions of extreme temperatures, 

 drought and lack of soil. From the 

 stage road along the Merced in the 

 lower end of Yosemite Valley look for 

 the large tree on a narrow ledge high 

 up on the rocky face of El Capitan. 

 Also see the smaller trees growing out 

 of apparently solid rock on the granite 

 knobs near Prospect Point and Mirror 

 Lake. The limber pine is the high 

 Alpine climber, its high inaccessible 

 range being from 8,000 to 12,000 feet 

 on the higher slopes and lower peaks of 

 the Sierras, where it exists as the 

 advance guard at the upper timber 

 line. The growth is very slow, the 

 limbs are often larger than the trunk 



which remains stunted, and trees only 

 a few feet high may be over 200 years 

 old. It is a distorted, dwarfed and 

 pathetic specimen, often hardly shoulder 

 high, and found clinging in situations 

 where vegetable life of any kind seems 

 impossible. 



The desert regions produce other 

 forms of tree growth which are unique 

 and unusual because of the long struggle 

 which has adapted them to existence 

 with a minimum of moisture. There 

 are regions in California where the 

 annual rainfall is less than 10 inches, 

 which by comparison with other por- 

 tions of the State which have a pre- 

 cipitation of 6 or 8 feet, produce a 

 striking parallel. There is a natural 

 relation between rainfall and tempera- 

 ture with the consequent extremes 

 between heat and cold, which also have 

 their effect upon tree growth. Then in 

 between lie all the gradations and over- 

 lapping conditions which produce the 



