CLIMATE AXD PLANT GROWTH. 



39 



61 Days 



\ 



\ 



95 Days 



X 



\ 



\ 



3/Days 



Oak-Brush 7yp6 



Aspen - Fir Spruce -Fir 



Temperature above 40°F 



Phys/'o/oc/ica/ temperature eff/c/ency 



S um of da/'/y m ear? 



Fig. 19. — Temperature efficiency summations for period of growth of plants used in main 



experiment. 



