THE FOREST EST WINTER. 205 



The Forest in Wmter. 



The influence of the woods on the flow of springs, and conse- 

 quently on the supply for the larger watercourses, naturally con- 

 nects itseK with the general question of the action of the forest 

 on the humidity of the ground. But the special condition of the 

 woodlands, as affected by snow and frost in the winter of exces- 

 sive chmates, like that of the United States, has not been so much 

 studied as it deserves ; and as it has a most important bearing on 

 the superficial hydrology of the earth, I shall make some observa- 

 tions upon it before I proceed to the direct discussion of the influ- 

 ence of the forest on the flow of springs. 



To estimate rightly the importance of the forest, in our climate, 

 as a natural apparatus for accumulating the water that falls upon 

 the surface and transmitting it to the subjacent strata, we must 

 compare the condition and properties of its soil with those of 

 cleared and cultivated earth, and examine the consequently differ- 

 ent action of these soils at different seasons of the year. The dis- 

 parity between them is greatest in climates where, as in the North- 

 ern American States and in the extreme north of Europe, the 

 open ground freezes and remains impervious to water during a 

 considerable part of the winter ; though, even in chmates where 

 the earth does not freeze at all, the woods have still an important 

 influence of the same character. The difference is yet greater in 

 countries which have regular wet and dry seasons, rain being very 

 frequent in the former period, while, in the latter, it scarcely oc- 

 curs at all. These countries He chiefly in or near the tropics, but 

 they are not wanting in higher latitudes ; for a large part of 

 Asiatic and even of European Turkey is almost wholly deprived 



that this power is so great that a plantation of eucalyptus acts as a veritable 

 drain on wet soils, but I do not know that the alleged facts on which this the- 

 ory rests have yet been verified by scientific observation. That there must ex- 

 ist some relation between nutrition and growth is too obvious to be doubted, 

 and the character and measure of this relation constitute one of the most urgent 

 and important of yet unsolved problems in vegetable physiology. In accord- 

 ance with the ordinary economy of Nature, who does nothing in vain, we 

 should presume that the absorbent powers of the roots of trees were limited to 

 the supply of elements of accretion to the tree, but we are too ignorant on thia 

 subject to aflirm positively that the fluid absorbed may not subserve some othei 

 function independent of the growth of the tree. 



