Germination of Forest Trees 



47 



It is evident from this table that the two most drought endur-. 

 ing species are Pinus ponderosa (S. D.) and Pinus ponder osa 

 (N. M.). While other species germinated in the dry soil their 

 germination per cents, were very small. Among the intermediate 

 species, as far as soil moisture goes, are Abies concolor, grandis, 

 and lasiocarpa, Pinus contorta, Pinus ponderosa (Mon.), and 

 Pseudotsuga taxifolia (Mon.). It is interesting to see that with 

 one exception the only species that germinated in the dry culture 

 were either Pinus ponderosa or Pseudotsuga taxifolia. The 

 former from the Black hills, New Mexico, and Southern Idaho 

 and the latter from New Mexico, Colorado, and Idaho. The line 

 is evidently driawn between Southern Idaho and Montana as to 

 whether these species will germinate in the dry culture or not, 

 since both species from Montana did not germinate in the dry 

 culture. Another interesting fact is that there are no moisture- 

 loving species in the Rocky Mountains so far as this classification 

 and these species are concerned, since there are no species that 

 germinated only in the wet soil. 



On page 46 are given the curves of Pinus ponderosa and 

 Pseudotsuga taxifolia in their relation to soil moisture. These 

 curves show that germination is delayed, the curve rises less 

 rapidly, the period is shorter, and the final per cent, lower with 

 a decrease in soil moisture. 



TABLE VI 



The Effect of Soil Moisture on Germination 



Pacific Coast Species 



Species 



Dry Soil 



C i/J 

 OS >> 



to as 



.2 >> 



. a 



Su 



Ph 



Medium Wet Soil 



- in 



to n! 



~0 w 



.2 >* 



PL,** 



!U 



Wet Soil 



to 



? 



. c 



Oh 



Pinus ponderosa (Calif.). 



Pinus Jeffrey i 



Pinus lamberliana 



Pinus coulleri 



Abies magnified 



Libocedrus decurrens . . . . 

 Sequoia washingtoniana . 



Tsuga heterophylla 



Picea sitkensis 



Larix occidentalis 



Pseudotsuga taxifolia. . . . 



68 

 80 



90 



20 



0.5 



12 

 6 



6.0 

 12.0 



3-0 



42 



3i 



70 



52 

 44 

 29 

 16 

 66 

 22 



67 

 77 

 36 

 4i 

 52 

 73 

 18 

 01 

 60 



22 



28 



61.0 



22.0 



2-5 



15-5 



18.0 



6.0 



7.0 



o-S 

 22.5 



6.0 



