﻿BOTANICAL GAZETTE 



of the white fir (Abies concolor). This tree, owing to its ability 

 to endure shade, persists under the brush, eventually forces its 

 way through, shades out the brush, and reestablishes forest con- 

 ditions. The difference is that the region in question possesses no 

 trees as tolerant of shade as the white fir. At the same time, the 

 scrub oak is never as dense as the Sierra brush, and offers in between 

 clumps openings in which the pine or better oaks can come up. The 

 pine, owing to its wider area of seed dissemination, has more oppor- 

 tunity than the oaks to take advantage of these openings, provided 

 seed trees remain. On the other hand, the oak, when once it 

 starts, stands a better chance of becoming established on account of 

 its power to sprout after being killed by fire. 



The foregoing, though by no means covering the whole case, 

 seems sufficient to show that the problem of succession so far as 

 pine and oak are concerned is extremely complex. It is of the 

 utmost importance that each case be considered by itself. So 

 many complex and interacting factors, such as the previous history 

 of the region (as emphasized by Taylor), the surrounding vege- 

 tation, and the soil and moisture conditions, enter into each case 

 that the conclusions of one locality may be wholly misleading when 

 applied to another locality only a few miles distant. 



