208 THE FOREST IN WINTER. 
ficial water; but when the cedars are felled, the swamp—which 
sometimes rather resembles a pool filled with aquatic trees than 
a grove upon solid ground—often dries up so completely as to 
be fit for cultivation without any other artificial drainage than, 
in the ordinary course of cultivation, is given to other new 
soils.* 
The Forest tr Winter. 
The influence of the woods on the flow of springs, and con- 
sequently on the supply for the larger water-courses, naturally 
connects itself with the general question of the action of the 
forest on the humidity of the ground. But the special condi- 
tion of the woodlands, as affected by snow and frost in the winter 
of excessive climates, like that of the United States, has not 
been so much studied as it deserves; and as it has a most impor- 
tant bearing on the superficial hydrology of the earth, I shall 
make some observations upon it before I proceed to the direct 
discussion of the influence of the forest on the flow of springs. 
To estimate rightly the importance of the forest in our cli- 
* A special desiccative influence has long been ascribed to the maritime 
pine, which has been extensively planted on the dunes and sand-plains of west- 
ern France, and it is well established that, under certain conditions, all trees, 
whether evergreen or deciduous, exercise this function, but there is no con- 
vincing proof that in the cases now referred to there is any difference in the 
mode of action of the two classes of trees. An article by D’Arbois de Jubain- 
ville in the Revue des Haux et Foréts for April, 1869, ascribing the same action 
to the Pinus sylvestris, has excited much attention in Europe, and the facts 
stated by this writer constitute the strongest evidence known to me in support 
of the alleged influence of evergreen trees, as distinguished from the draining 
by downward conduction, which is a function exercised by all trees, under 
ordinary circumstances, in proportion to their penetration of a bibulous sub- 
soil by tap or other descending roots. The question has been ably discussed by 
Béraud in the Revue des Deux Mondes for April, 1870, the result being that 
the drying of the soil by pines is due simply to conduction by the roots, whatever 
may be the foliage of the tree. See post: Influence of the Forest on Flow of 
Springs. 
It is however certain, I believe, that evergreens exhale more moisture in 
winter than leafless deciduous trees, and consequently some weight is to be as- 
cribed to this element, 
