802 PROPORTION OF WOODLAND. 
estuaries are choked up, and harbors which once sheltered large 
navies are shoaled by dangerous sand-bars. The earth, stripped 
of its vegetable glebe, grows less and less productive, and, con- 
sequently, less able to protect itself by weaving a new network 
of roots to bind its particles together, a new carpeting of turf 
to shield it from wind and sun and scouring rain. Gradually 
it becomes altogether barren. The washing of the soil from 
the mountains leaves bare ridges of sterile rock, and the rich 
organic mould which covered them, now swept down into the 
dank low grounds, promotes a luxuriance of aquatic vegetation 
that breeds fever, and more insidious forms of mortal disease, 
by its decay, and thus the earth is rendered no longer fit for 
the habitation of man.* 
To the general truth of this sad picture there are many ex- 
ceptions, even in countries of excessive climates. Some of 
these are due to favorable conditions of surface, of geological 
structure, and of the distribution of rain; in many others, the 
evil consequences of man’s improvidence have not yet been ex- 
perienced, only because a sufficient time has not elapsed, since 
the felling of the forest, to allow them to develop themselves. 
But the vengeance of nature for the vielation of her harmonies, 
though slow, is sure, and the gradual deterioration of soil and 
climate in such exceptional regions is as certain to result from 
the destruction of the woods as is any natural effect to follow its 
cause. 
Due Proportion of Woodland. 
The proportion of woodland that ought to be permanently 
maintained for its geographical and atmospheric influences 
varies according to the character of soil, surface, and climate. 
* Almost every narrative of travel in those countries which were the earliest 
seats of civilization, contains evidence of the truth of these general statements, 
and this evidence is presented with more or less detail in most of the special 
works on the forest which I have occasion tocite. I may refer particularly to 
HouenstEeIn, Der Wald, 1860, as full of important facts on this subject. See 
also CAIMI, Cenni sulla Importanza det Boschi, for some statistics, not readily 
found elsewhere, on this and other topics connected with the forest. 
