It is certain that everywhere in the northern prairie states a grove that breaks the force of the cold winds from the north and west adds greatly to the value of a farm. And it is gratifying to learn that so much tree planting has already been done in those states. Some have even been so sanguine as to predict that when the soft and hard timber of Michigan, Wisconsin and Minnesota is gone these new prairie states may be able—at least partially—to supply the needs of those just named, whose forests were confidently asserted to be inexhaustible.
The effect of certain trees—indeed, of almost any—as fences against malarious winds has been carefully studied in France and Italy, and the verdict is that it is very great.
Marsh (“Earth as Modified by Human Action,” p. 159) says: “It is well known that the great swamps of Virginia and the Carolinas, in climates nearly similar to that of Italy, are healthy even to the white man, so long as the forests in and around them remain, but become very insalubrious when the woods are felled.” He quotes Jules Clavé, a French expert, as authority for the statement that “the flat and marshy district of the Sologne, in France, was salubrious till its woods were felled. It then became pestilential, but within the last few years its healthfulness has been restored by forest plantations.” Marsh also thinks that in Germany and India belts of trees have been found very beneficial in warding off cholera. A lumber journal recently asserted that cholera has never prevailed in pine-producing districts.
Lanisci says that in the time of Gregory VIII. (who came to the papal chair in 1572 and reformed the calendar) Rome became much more unhealthful when a pine forest lying to the south was cut down because infested by brigands. The abbey of Trois Fontaines, considered one of the worst places in the fever infested Roman _campagna_, was much improved in three years by plantations of the Eucalyptus, and this tree has been used with good effect for the same purpose in the French settlements in Algeria (Hough, U.S. Forestry Report for 1877, p. 285).
Of the service rendered by forests in preventing the drifting of sands (_e_) the most remarkable instance is afforded by the once dreary regions in the extreme southwestern part of France, where plantations of the maritime pine have, in the departments of the _Landes_ and _Gironde_ transformed over 4,000 square miles of poverty-stricken country into populous hives of an intelligent and thrifty population. In the lower part of the valley of the Wisconsin river, much loss and inconvenience is experienced by the drifting of the sand which, driven by the prevailing west winds, covers and ruins fields and gardens, and in many cases, even fences. A few belts of timber running across that valley would be worth many times their cost in preventing this nuisance.