176 



Temperature 



Fig. 5.17. Winter view of tree line on Mt. Mansfield, Vermont, with spruce trees 



in foreground encased in ice. Severe frost action and other adverse climatic 



influences reduce the trees to stunted dwarfs. 



Photo by D. B. Clarke 

 Fig. 5.18. General view in midsummer of tree line on Mt. Rainier, Washington, 

 and of the alpine meadows above it. Tree line here is believed to be relatively 

 stationary because of the occurrence of both old and young trees among the out- 

 posts of the forest. 



