and sand content. The results of soil sample analysis indicated soil nutri- 

 ents were not limiting factors influencing vegetative recovery at any of 

 ttie 25 study sites. 



The initial reco I on i zat i on of these disturbed areas most frequently oc- 

 curred by seed development; at several locations, however, willows had 

 reinvaded through development of adventitious stems and roots from old woody 

 slash and root stocks. Adventitious stem development occurred most often in 

 overburden piles where woody slash was placed. All overburden piles occurred 

 in sites developed before 1971. More recent regulation of gravel removal 

 activities require overburden and woody cover to be removed completely from 

 f I oodp lain s i tes . 



In general, herbaceous species dominated in those pioneer communities 

 which were developing from seed. However, Salix alaxensis was a frequent 

 member of these communities in all four geographic regions, and seedling 

 Betu I a papyr i f er a and Popu I us balsamifera commonly occurred in pioneer 

 communities at several Northern Interior sites. Taxa that most often were 

 dominant in these invading communities included Epilobium latifolium, Salix 

 a I axens i s , Sa I i x spp., Equisetum variegatum, Stellaria spp., Hedysarum 

 Mackenz i i , Astr aga I us spp., Oxytropis spp., Juncus spp., Carex spp., Eriopho- 

 rum spp., Ca I amagrost i s spp., and Poa spp. In soils that were less moist and 

 more coarse, Ar temis i a spp., Crepis nana. Aster sibiricus, and Erigeron spp. 

 frequently occurred as initial invaders. 



Overburden was piled either within the disturbed area or at its edge at 

 many of the older sites. At the Penny River and Washington and McManus 

 Creeks these overburden piles contained many organics and woody slash, root 

 stocks, and debris. At Penny River, three piles of material were located 

 within the 15-ha site (Figure 65). At Washington Creek, one pile was placed 

 in the middle of the 3-ha site and one on its edge, and at McManus Creek the 

 organic overburden was all piled on the edge of the 4-ha disturbed area. 

 These piles averaged I to 2 m in height, however, a few were 5 to 7 m 

 ( F i gure 66 ) . 



At all three sites, herbaceous and woody vegetation were well estab- 

 lished on the overburden piles within I year after disturbance. Development 



233 



