Germination of Forest Trees yy 



the per cent, in favor of the large seeds. In converting grams 

 to pounds it was assumed that 453.6 grams equals one pound. 

 The germination period for Pinus ponder osa was 120 days and 

 for Pseudotsnga taxifolia 100 days. 



From these tables it will be seen that in every variety of Pinus 

 ponderosa the final germination per cent, is in favor of the large 

 seeds. In the case of Pseudotsuga taxifolia every variety except 

 one shows a final per cent, in favor of the large seeds. 



It is well known that there are definite climatic differences 

 between the Rocky Mountains and the Pacific coast. The most 

 conspicuous proof of this is in the flora of these regions. In 

 general the Pacific coast is inhabited by relatively mesophilous 

 vegetation, especially near the coast, while the vegetation of the 

 Rocky Mountains is more xerophilous in nature. Again, the 

 Rockies themselves show marked differences in this very respect 

 in travelling from south to north and from east to west. 



Probably the best way of studying the effect of great climatic 

 variations upon vegetation is to use polydemic species such as we 

 are considering here. Pinus ponderosa and Pseudotsuga taxi- 

 folia are conspicuous examples of this class of species. It is 

 well known that both these species reach a better development on 

 the Pacific coast than in the Rocky Mountains. It is likewise 

 well known that they reach a far better development in the 

 northern Rockies than in the southern. As a proof of this we 

 have but to go to volume tables of these species in the Woods- 

 man's Handbook by Graves and Ziegler. In the case of Pinus 

 ponderosa three tables are given, one for the Black Hills, one for 

 Arizona, and one for California and Montana. In studying 

 these tables it will be seen that the maximum heights and 

 maximum diameters and the average and maximum heights for 

 a given diameter increase steadily in going from the Black Hills 

 to California. In the case of the Douglas fir the same thing is 

 true in considering the volume table for Idaho and Wyoming 

 and that for Washington and Oregon. In the order of their 

 favorability for tree growth, as manifested by these species these 

 regions arrange themselves in the following order, the least favor- 

 able being given first : 



