Thus, scraped sites located on sharp inside bends led to the formation 

 of cut-off channels unless extensive vegetated buffers (Jim River) or natur- 

 ally contoured channel slopes (Shaviovik River) were maintained during the 

 gravel removal operation. These cut-off channels subjected the mined areas 

 to frequent or permanent ponding and flooding which impeded vegetative 

 recovery . 



Additional Similarities . Overburden piles, as previously discussed, 

 were a positive addition at sites annually subjected to ponding, flooding, 

 and aufe i s deve I opment . At sites where piles occurred, Biotic Group II 

 (primarily small mammals, ground squirrels, and early shrub communities) 

 increased (Site Response Group B, D, and E, Table 34). However, at sites 

 where overburden piles did not occur, but the site received annual hydraulic 

 stress of flooding, permanent ponding, or aufeis development, Biotic Group 

 II decreased (Site Response Group C). 



Overburden piles occurred in a variety of shapes and sizes and were 

 placed in various locations within the material site. From a revegetative 

 viewpoint the most effective pile compositions were those with a mixture of 

 silts, organics, woody slash, root stocks, and debris. These piles only 

 occurred at the older sites and all were at least I to 1.5 m above normal 

 water levels. It is not known if additional piles of lower height originally 

 occurred and had been eroded and removed by flood waters. Also, all piles 

 that were within the central portions of the mined areas were either not 

 directly in the path of main currents or were placed in windrows oriented 

 parallel to the current. Overburden piles that remained in the middle of 

 large scraped sites were judged to be of more overal I benefit than those 

 placed on the edge of the disturbed areas. These piles provided immediate 

 denning habitat for ground squirrels and, within several years, began to 

 provide cover and nesting habitat for small mammals and passerines within 

 the central portions of large mined areas. 



The effectiveness of natural buffers was related to their location and 

 dimensions in relation to river size and configuration. Twelve of the 25 

 study sites included some use of buffers. Two types were employed: 



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