442 APPENDIX. 



each other, it would appear that the forest exerts a cooling 

 influence, but that more detailed conclusions are hindered by 

 the consideration that the ordinary meteorological station 

 itself is somewhat affected by neighboring trees. 



The study of the stations in Asiatic and European Russia 

 seems to show that in the western part of the Old World the 

 presence of large forests has a very sensible influence on the 

 temperature. Similar studies for stations in the United States 

 seem to show that our thin forests have a slight effect in 

 December, but a more decided one in June. It appears also 

 that our wooded regions are warmer than the open plains, but 

 there is no positive evidence that this difference of tempera- 

 ture is dependent upon the quantity or distribution of forests 

 or that changes in temperature have occurred from this cause. 



(5) When a forest encloses a small area of land, forming a 

 glade, its enclosed position brings about special phenomena of 

 reflection of heat, local winds, and a large amount of shade. 

 For such situations it is found that the mean range of tem- 

 perature is larger in the glade than in the open ; the glade 

 climate is more rigorous than the climate of open plains ; the 

 glade is cooler and its diurnal range larger during the spring, 

 summer, and autumn. 



Favorable influences upon moisture conditions of the air 

 are most noticeable in localities where much water is stored 

 underground, with overlying strata which are apt to dry when 

 our summer drought prevails. Here the forest growth is 

 able to draw water from greater depths, and by transpiration 

 return it to the atmosphere, thereby reducing the dryness 

 and possibly inducing precipitation. In moist climates this 

 action would be less effective or of no use. Hence in regions 

 with oceanic climate, with moist sea winds, like England and 

 the west coasts of Europe or of the northern United States, 

 deforestation from a climatic point of view may make no 

 appreciable difference, such as it would make in continental 

 climates like the interior of our country, the Rocky Mountains, 

 and Southern California. 



