THE USE OF VEGETATION IN EROSION CONTROL 



Vegetation acts in the following ways to control erosion: 

 1) the precipitation is intercepted by leaves, which reduces the direct 

 impact of rain on bare soil, 2) the rate of runoff is retarded, especially by 

 grasses and ground covers, 3) small soil particles are filtered and re- 

 tained, 4) the soil is mechanically reinforced by roots, 5) deep roots may 

 penetrate unstable soil layers, and 6) excess soil moisture can be reduced 

 by plants through the process of transpiration (Fig. 2). 



Most previous work on the use of vegetation for erosion control 

 has concentrated on highway slopes and construction sites such as dams. 

 These areas receive full sunlight, and consequently, the plants used there 

 are not suitable for use in heavily wooded ravines. To our knowledge, no 

 experimental plantings have ever been done in wooded situations in the 

 Midwest to ascertain which plants are most effective in controlling erosion. 

 Therefore, the recommendations of this report are the best that can be 

 given with the present state of knowledge, but they should not be considered 

 definitive solutions to the erosion problems in the ravines. The basic 

 premise of our recommendations is that when the ravine vegetation is mature 

 and healthy, erosion is at a minimum; any changes to such vegetation would 

 not reduce the erosion rate. The plants recommended for planting in the 

 ravines are those that occur naturally or that have been successfully planted 

 in the past. 



MAINTENANCE OF RAVINE VEGETATION 



It is often said that ravine vegetation can take care of Itself. 

 This is true only to a certain degree. Over long periods of time, the vege- 

 tation in ravines changes. The amount of change depends on many factors, 

 such as physical environment and the changes attributable to man's activities. 

 The plants that survive and reproduce in ravines do so because of their 



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