34 BULLETIN 675, U. S. DEPARTMENT OF AGRICULTURE. 



revegetated. The establishment of terraces and subsequent planting 

 in suitable native species, therefore, offers considerable promise on 

 lands that have eroded to such a point that revegetation is extremely 

 slow and the subterranean parts of the vegetation uneffective in 

 binding the soil and in preventing erratic run-off. The cost of the 

 establishment of terraces will vary greatly according to the depth and 

 number of gullies and the amount of fill work necessary. Where a 

 moderate stand of native vegetation occurs within the vicinity of 

 the terraces it will not be necessary to plant directly, provided a satis- 

 factory seed crop is produced. 



CONSTKTJCTION OF DAMS. 



In various parts of Europe, notably in the Swiss Alps, and to a 

 less extent in this country, elaborate earth, stone, and concrete dams 

 have been constructed where the less expensive contour terraces are 

 inadequate in preventing continued destructiveness from erosion in 

 critical localities. Obviously, the construction of elaborate dams is 

 expensive and their use is limited to situations where the destruction 

 to personal and other property is of much more than average seri- 

 ousness. Problems of this character properly fall under the scope 

 of engineering. 



SUMMARY OF PREVENTIVE AND REMEDIAL MEASURES. 



The maintenance of an effective vegetative cover may be accom- 

 plished by the following means: 



1. Avoidance of overgrazing. 



2. Avoidance of too early grazing. 



3. Deferred and rotation grazing. 



4. Artificial reseeding (in choice sites only). 



5. Proper control and distribution of stock. 



Where the depletion of the soil and the formation of long estab- 

 lished gullies make thorough revegetation impossible, destructive 

 floods and erosion may be controlled in the following ways : 



1. Total exclusion of stock. 



2. Terracing and planting. 



3. Construction of dams. 



CONCLUSIONS. 



1. Erratic run-off and erosion have been responsible for a great deal 

 of damage on western ranges where the vegetative cover had pre- 

 viously been materially decreased or practically eliminated. 



2. Though the damage from erosion usually is measured merely 

 by the injury caused to farm land and works of construction, the 

 damage to the forest range lands upon which erosion occurs is often 



