RANGE PRESERVATION AND EROSION CONTROL,. 



33 



is smoothed out by means of a homemade terrace drag (fig. 8). The 

 drag is constructed in a V-shape and can be made any \vi<h h prcn ided 

 the proportions are followed as given in the sketch. In order that 

 the drag may work effectively one or two men usually stand on the 

 crosspiece supporting the side beams. As soon as the terrace is well 

 smoothed it is ready for planting. 



Planting early in the spring before growth has stalled has given 

 the best results; and since the soil can not be worked satisfactorily 

 at that time terraces can best be established in the autumn. At the 

 intersection of the more prominent gullies and the terraces, the 

 former are built up with rock butts and overlaid with soil. In order 

 to hold the terrace soil as effectively as possible, the terraces are 

 planted to such soil-binding species as wild gooseberry (Grossularia) , 

 mountain elder (Sambucus), yellow brush (Ghrysothamnus), sweet 

 sage (Artemisia), yarrow (Achillea), and several species of sub- 



Fig. 8. — Terrace drag. 



alpine grasses. Since seed of native grasses, which soon become 

 firmly established on the terraces, can not be purchased from com- 

 mercial seed houses it has been necessary to collect seed wherever a 

 good crop developed^ naturally. However, following the establish- 

 ment of the terrace a great deal of seed of native species is caught 

 during the natural seed dissemination period in the autumn, and in 

 two seasons or so the terraces become fairly well vegetated. As 

 the soil is enriched through the accumulation of decayed vegetable 

 matter, conditions for growth are gradually made more favorable 

 and the vegetation develops luxuriantly. 



The area experimented with, prior to the establishment of the ter- 

 races and fill work, had been subject each season to serious erosion. 

 Since, the establishment of the terraces and supplemental work, no 

 erosion whatsoever has occurred and the lands are generally becoming 



