184 Temperature 



over the continent of certain vegetational life forms. The scheme 

 presented in Fig. 5.22 shows in diagrammatic fashion that above a 

 certain vakie of thermal efficiency, moisture tends to be more re- 

 sponsible than temperature for the control of life form. In colder 

 climates temperature is generally more important. Soil groups are 

 influenced in a similar way by the climate as well as by the vegeta- 

 tion. With low precipitation-evaporation ratios and high tempera- 

 tures the moisture factor is more significant than the heat factor. In 

 the far north the temperature is by far the more critical, but in inter- 

 mediate regions moisture and temperature play more nearly equal 

 roles in determining soil groups. Here then we have another illustra- 

 tion of the extremely wide direct and indirect influences of the tem- 

 perature factor in the ecological adjustments of both plants and ani- 

 mals. 



