piles of organics, silts and sands supported advanced serai stage shrub 

 thickets. The undesirable material was of unknown substance, but appeared to 

 be a mica-like material. 



The average growing season varies from approximately 130 to 150 days in 

 the Souther Interior, from 100 to 120 days on the Seward Peninsula, and 

 from 75 to 95 days on the North Slope (Mitchel personal communication). This 

 factor was believed to be strongly influencing the rate of vegetative recov- 

 ery at the two most northern study sites (Ugnuravik and Kuparuk Rivers). 

 Both sites were only 6 km inland from the Arctic Ocean and at both sites 

 vegetative recovery in nonflooded areas was progressing very slowly even 

 when compared to similarly aged North Slope sites (7 and 9 years) located 80 

 to 90 km inland. 



Enhancements 



Several factors were found to enhance vegetative recovery, the most 

 significant of which appeared to be the presence of organic soil with woody 

 slash and debris. This material was most effective when placed in piles that 

 were higher than frequent flood levels, or broadcast in those portions of 

 the disturbed site where it would not get washed downstream or frequently 

 flooded by high water. 



Overburden piles occurred at I I of the 25 study sites, however, only at 

 those sites where this overburden contained organics with fine textured 

 soils (silts and sands) and woody slash and debris, was vegetative recovery 

 most enhanced. Instead of being placed in piles, this material was broadcast 

 over the surface at two additional sites (Aufeis Creek and Middle Fork 

 Koyukuk River-Downstream). At both sites, this material was placed in areas 

 where it was not stressed by high water levels. At both sites these 2- to 

 4-ha areas were the first to begin natural revegetation and supported the 

 most diverse and most developed communities. Revegetation began the first 

 growing season following completion of gravel removal at both sites. Develop- 

 ment of adventitious stems was the prime method of revegetation by willow 

 (F igure 75 ) . 



245 



