This section is from the book "A Few Suggestions On Tree Planting", by C. S. Sargent.
Lupham mentions that " such has been the changes in the flow of the Milwaukee River, even while the area from which it receives its supply is but partially cleared, that the proprietors of most of the mills and factories have found it necessary to resort to the use of steam, at a largely increased yearly cost, to supply the deficiency of water-power in dry seasons of the year. The floods of spring are increased until they are sufficient to carry away bridges and dams before deemed secure against their ravages. What has happened to the Milwaukee River has happened to all other watercourses in the State from whose banks the forests have been removed, ard many farmers who selected land upon which there was a living brook of clear, pure water, now find the brooks dried up during a considerable portion of the year".
* Trees of America. R. U. Piper, Boston, 1855.
Many such examples might be instanced to prove that cutting off the forests has a direct influence in diminishing the flow of springs, but I will confine myself to one other.
Marschand, as quoted by Mr. Marsh, cites the following: "The Wolf Spring, in the commune of Soubey (France), furnishes a remarkable example of the influence of woods upon fountains. A few years ago this spring did not exist. At the place where it now rises a small thread of water was observed after very long rains, but the stream disappeared with the rain. The spot is in the middle of a very steep pasture, inclining to the south. Eighty years ago the. owner of the land, perceiving that young firs were shooting up in the upper part of it, determined to lot them grow, and they soon formed a flourishing growth.
" As soon as they were well grown, a fine spring appeared in place of the occasional rill, and furnished abundant water in the longest droughts. For forty or fifty years the spring was considered the best in the Clos du Doubs. A few years since the grove was felled, and the ground turned again to a pasture. The spring disappeared with the wood and is now as dry as it was ninety years ago. "
The influence of belts of trees, especially of spiked-leaved species, on local climate is important. Such plantations serve as a material check to the natural force of the cold winds from the north, which rapidly lower the temperature, hasten evaporation, and blow into drifts the snow which would otherwise protect the ground with an even covering. There is probably no way in which the farmers of this State could more easily or more rapidly increase its agricultural product than by planting such screens from the northeast to the northwest of their farms ; and their attention is particularly directed to the importance of this subject Such plantations would be too limited in extent and too widely scattered to have any general influence on our climate, or the flow of our watercourses; but, as a means of direct profit, it does not seem unreasonable to predict that such protection to our fields would increase the profits of their cultivation fully twenty per cent.
Orchards thus protected are still productive, and all gardeners know that plants generally supposed too tender to support our climate will thrive when planted under the protection of a garden wall, or among evergreen trees. What garden walls are to the horticulturist, these broad evergreen plantations should be to the farmer.
Mr. J. J. Thomas, as quoted by Lapham, says, "Isaac Pullen, a well-known nurseryman at Ilightown, N. J., showed me last summer (1864) several belts of evergreen trees which had sprung up from his nursery rows to a height of twenty-five or thirty feet in ten years, and he stated that within the shelter of these screens his nursery-trees, as well as farm crops, averaged fifty per cent more than in blank or exposed places".
Becquerel, as quoted by Mr. Marsh, says, " In the valley of the Rhone a simple hedge two metres in height is sufficient protection for a distance of twenty-two metres." " The mechanical shelter," says Mr. Marsh, " acts, no doubt, chiefly as a defence against the mechanical force of the wind; but its uses are by no means limited to that effect. If the current of air which it resists moves horizontally, it would prevent the access of cold or parching blasts to the ground for a great distance." " Becquerel's views," says the same author, " have been amply confirmed by recent extensive experiments on the bleak, stony, and desolate plain of the Crau in the department of the Bouches du Rhone, which had remained a naked waste from the earliest ages of history. Belts of trees prove a secure protection even against the piercing and chilly blasts of the Mistral, and in their shelter plantations of fruit-trees and vegetables thrive with the greatest luxuriance." Experiments of a similar nature, and on a large scale, have been made in Holland, and lands which were formerly considered unimprovable, such was the force of the winds blowing from the North Sea, have been rendered almost the most productive in Europe simply by sheltering them with rows of trees placed at regular intervals, and at right angles to the direction of the wind.
It appears, then, that in a country in which a due proportion of forest was maintained, it might be expected that local summer showers would probably be attracted; that extremes of temperature both in summer and winter would be prevented to such an extent that additional crops would be made possible; and that the annual rainfall, instead of being rapidly wasted by evaporation, or still more rapidly poured into the sea, would be held in the forest-clad ground, from which it would gradually find its way to the water-courses, which would flow regularly throughout the year, bringing summer verdure to pastures, and assured power to the manufactories along their banks.
But these are national questions, and can only be treated in a broad, comprehensive manner. Let us consider, however, whether Massachusetts is furnishing her quota to the national forest system which would return to our country much of its lost fertility. It has been estimated, and, I think, with correctness, that forests, in order to maintain normal physical conditions, and to supply the material so essential to every branch of human industry, should occupy about twenty-five per cent of the area of the country to be influenced and supplied by them.