Germination of Forest Trees 



43 



a higher per cent, in the medium shade, and six a higher per 

 cent, in the dense shade than in the other cultures. 



On page 42 are given the germination curves of Pseudotsuga 

 taxi folia (Wash.), and Picea sitkensis. Both sets of curves show 

 that germination begins sooner, the curve rises more rapidly and 

 the final germination per cent, is higher in the case of seeds 

 germinated in the shade as compared to light. 



TABLE IV 



The Effect of Soil Moisture on Germination 

 Eastern Species 



Species 



Dry Soil 



bn a 

 1- 



T3 tfl 

 O >, 



. c 

 3u 



d, 



Medium Wet Soil 



G t 

 at a 



"O if, 



.2 >> 



go 



0/ 



Wet Soil 



- - 

 1:- 





. C 



Ph 



Pinus strobus 



Pinus divaricata 



Pinus divaricata (F. S.) 



Pinus resinosa 



Pinus palustris 



Pinus taeda 



Abies balsamea 



Catalpa speciosa 



Calalpa speciosa (Neb.) , 



Quercus rubra 



Robinia psendacacia . . . . 



Betula papyrifera 



Acer rubrutn 



40 24 

 28 ' 12 

 68 1 



10. o 



7-5 

 2.5 



30 



14 

 22 



24 

 36 



34 

 50 

 18 



8.0 



53-5 

 4.0 



40 : 49.0 

 50 6.0 



22 



22 



10 . 30 



15.0 



22 



8 



12.0 



24 



3-0 



24 



4.0 

 32 ; 32.0 

 26 12.0 



22 



12 



14 

 24 



3i 

 34 

 18 

 18 

 16 

 40 

 8 



34 

 18 



50 

 32 

 20 

 16 



53 



6 



30 



1 

 12 

 28 

 16 



1 

 30 



10.7 

 54-5 

 39-5 

 30.5 

 10.5 

 19.0 

 11. o 



1.0 

 91.0 

 28.0 

 28.8 



1.0 



17.0 



Tables IV, V, and VI consider the same species as the three 

 preceding tables from the standpoint of soil moisture instead of 

 light. 



In Table IV in practically every case where a comparison is 

 possible germination started in the wet soil culture, and was de- 

 layed as the soil moisture content was reduced. Also the germi- 

 nation period is shortened with decrease in soil moisture. The 

 final germination per cent, in every case but one was highest in 

 the wet soil. Pinus resinosa showed the highest per cent, in the 

 medium wet soil. 



This table separates the species into classes based upon their 

 ability to germinate in dry soil, medium wet soil, or wet soil 



