Based on the above studies of rooting characteristics, ponderosa pine seems to be 

 morphologically well suited to providing mechanical stability for mass erosion on 

 road fills, certainly better suited than grass. Use of this species for erosion control 

 on road fills in the Idaho Batholith has other advantages, Ponderosa pine is a valu- 

 able commercial species throughout its range. In addition, planting stock is readily 

 available from local nurseries, as is seed to a somewhat lesser degree. Finally, the 

 si Ivies and forest management practices for ponderosa pine are known and accepted for 

 the most part by land managers. 



The present study was designed to evaluate the effect of ponderosa pine with and 

 without surface amendments on surface erosion. Seeded grass plots were also included 

 to provide a comparison with earlier studies. No attempt was made to evaluate decreases 

 in mass erosion hazard due to tree planting because such studies are extremely involved 

 and beyond the scope of present efforts and because studies elsewhere provide strong 

 evidence that ponderosa pine should increase the mass stability of granitic road fills. 

 Other objectives of the present study were to provide information on tree survival and 

 growth and some insight into the basic surface erosion processes occurring on granitic 

 road fills. This report will be devoted to evaluating the effects of ponderosa pine on 

 surface erosion and to presenting data on tree survival and growth. Results pertaining 

 to basic erosion processes will be reported elsewhere. 



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