The larger rivers within all four regions typically flowed in braided 

 or split channel configurations. These floodplains were more hydr au I i ca I I y 

 dynamic, with much wider active areas, and contained advanced serai stage 

 vegetative communities only along floodplain borders and on isolated mid- 

 channel islands. Much of the floodplain in these large, braided rivers 

 contained expansive areas of unvegetated gravels or were sparsely vegetated 

 with herbaceous and woody pioneer or early shrub thicket communities. 



This very briefly describes In general terms the normal vegetative 

 patterns of floodplains in the area of study. For a more detailed descrip- 

 tion of normal patterns, refer to the "Preliminary Report Gravel Removal 

 Studies in Selected Arctic and Sub-Arctic Streams in Alaska" (Woodward-Clyde 

 Consultants 1976) and for a detailed description of the vegetative structure 

 which occurred at each study site refer to the Project Data Base. 



VEGETATIVE COMMUNITY CHANGES AT GRAVEL REMOVAL SITES 



The observed changes in vegetative communities of the study sites 

 varied from no significant change to long-term loss of habitat. Habitat loss 

 and alteration (both short-term and long-term) repeatedly resulted in signif- 

 icant secondary changes within the bird and mammal populations that inhab- 

 ited study area floodplains. These faunal responses are discussed in a 

 fo I lowi ng sect i on. 



Significant areas of existing floodplain vegetative cover were removed 

 at 18 of the 25 sites (Table 28). Lost vegetative habitats usually consisted 

 of mature shrub thickets on the Seward Peninsula and North Slope sites, and 

 a mixture of shrub thickets and advanced successional stages of boreal 

 forest floodplain communities in Northern and Southern Interior regions. At 

 all sites these habitats supported a diverse and abundant fauna dominated by 

 passerines and sma I I mammals prior to clearing and gravel removal activ- 

 ities. Refer to the Project Data Base for a complete listing of recorded 

 flora and fauna at each study site. 



Vegetative habitat removed at these 18 sites averaged 10 ha and ranged 

 from approximately I ha at Gold Run Creek to 35 ha at Dietrich River- 

 Upstream (Tab le 28) . 



225 



