110 Methods of Beboisemevt. 



may provide the best defense. If seeds are sown, it may be neces- 

 sary to cover them with brush, that is fastened down with stakes. 

 Under this cover, the plants may get well rooted ; and if this is se- 

 cured, the success of the work is certain. 



Reboimment. 



432. By- " reboisement," we mean the planting of woodlands 

 where they have been destroyed, and especially where their destruc- 

 tion has caused great injury from torrents by the eroding of mountain 

 sides, and covering the valleys below with stone and gravel. The 

 desolation and sterility thus occasioned is increased by pasturage, 

 especially by sheep and goats, so that regions once highly fertile 

 and densely populated have often become utterly desolate and 

 solitary. 



433. In recent years, most European governments have taken 

 measures to stop these ruinous practices, and have with much suc- 

 cess, but at vast expense, secured a gradual return of fertility, and 

 an effectual prevention of future injuries. These measures may be 

 described under two heads : 



(a.) Barriers for cheeking €ie Torrents. 



434. These are made of stone, in the bottoms of the ravines, and 

 convex up-stream, the top being lowest in the middle. They are 

 sometimes made of bundles of willow securely fastened down. 

 They will then often spout and grow, thus by their roots preventing 

 further erosion. 



(6.) Reboisement of the deivuded Slopes. 



435. This is by far the most important, and often the more diffi- 

 cult work to be done, as it tends to prevent the formation of the 

 torrents. The rains that fall upon a wooded, or even a sodded 

 slope, have their force broken, and they quietly filter into the soil, 

 or flovv down with so many obstiuctions that they do no iujurv. 

 But on a bare surface, they begin to wear little channels, which 

 presently enlarge in width and depth, till they become enormous 

 chasms. 



436. To secure a wooded or sheltered surface, the soil should be 



