This section is from the book "A Few Suggestions On Tree Planting", by C. S. Sargent.
Our agricultural population is not easily convinced of the necessity of tree-planting. The benefits arc too vague, the profits too prospective, to cause them to look with enthusiasm on what seems a doubtful undertaking.
Still, in this respect, public opinion is gradually changing, and already in many of the States of the Union experiments in sylviculture are being made on a sufficient scale to promise the most gratifying results, and it is not improbable that at no distant day, when its benefits are more clearly understood, this branch of agriculture will receive at the hands of our farmers the attention its importance demands.
Proof is wanting that the; total average rainfall has been reduced, either in this country or Europe, by cutting off the forests. Rut examples are often cited in proof that forests play an important part in regulating and attracting summer rains and local showers; and it is not improbable, were more data in the form of carefully conducted observations available, that some theory on this subject might be deduced. Certainly, as Mr. Marsh remarks in his admirable book on physical geography * " it is impossible to suppose that a dense cloud, a sea of vapor, can pass over miles of surface bristling with good conductors without undergoing and producing some change of electrical condition".
The following interesting illustrations arc not without value as vaguely indicating in what direction we must turn for an explanation of the summer droughts, which, in certain portions of the country, have increased of late to an alarming extent. In Massachusetts, however, some cause outside the destruction of the forests must be sought for; as in the earliest history of the Colony, and long before land enough had been cleared to induce any climatic change, the country was nearly devastated by severe summer droughts, which, if less frequent, were no less violent than those of the present day.
* The Earth as modified by Human Action. George P. Marsh. New York, 1874.
Mr. Calvin Chamberlain, in an able memorial on the subject of forests* presented to the House of Representatives of the State of Maine in 1869, says, " There is a portion of Hancock County (Maine), along the coast, that is now nearly denuded of trees. During the heat of summer the radiation from the parched surface affects the atmosphere to excessive dryness. The electrical and rain-bearing clouds that approach from the westward, as they come within this dry atmosphere, are absorbed and dissipated before their watery contents can reach the earth; while the clouds just north of them float on over a better wooded district and yield a copious rainfall; and, on the other hand, the showers continue abundant in the more humid atmosphere of the contiguous bays and ocean".
Dr. Lapham † observes that "in the hot and dry plains of our southwestern territories we often see clouds passing overhead that reserve their contents until they have passed from these almost desert regions. These clouds frequently present all the actual appearance of rain in the higher region of the atmosphere, and the fertile-giving drops are seen to fall far down towards the earth, only to be dissolved and dissipated in the lower strata of air, heated by the reflection from the parched earth, which these raindrops do not reach".
As moderators of the extremes of heat and cold, the benefits derived from extensive forests are undoubted, and that our climate is gradually changing through their destruction is apparent to the most casual observer. Our springs are later; our summers are drier, and every year becoming more so; our autumns are carried forward into winter, while our winter climate is subject to far greater changes of temperature than formerly. The total average snowfall is, perhaps, as great as ever, but it is certainly less regular, and covers the ground for a shorter period than formerly. It is interesting to note in this connection the conclusion which Noah Webster ‡ drew three quarters of a century ago, showing that, even at that time, before the cutting-off the forests had assumed the importance which it does to-day, similar climatic changes were at work. "From a careful comparison of these facts," he says, " it appears that the weather in modern winters in the United States is more inconstant than when the earth was covered with woods, at the first settlement of Europeans in this country; that the warm weather of autumn extends further into the winter months, and the cold weather of winter and spring encroaches upon the summer; that the wind being more variable, snow is less permanent; and perhaps the same remark may be applicable to the ice of the rivers." Mr. Marsh arrives at nearly the same conclusion. " So far as we are able to sum up the results," he says, " it would appear that in countries in the temperate zone, still chiefly covered with woods, the summers would be cooler, shorter; the winters milder, drier, longer than in the same regions after the removal of the forests, and the condensation and precipitation of atmospheric moisture would be, if not greater in total quantity, more frequent and less violent in discharge".
* Agriculture of Maine. Second Series. 1809.
† Report of the Disastrous Effects of the Destruction of Forest Trees now going on so rapidly in the State of "Wisconsin. 1867.