Eriophorum angustilolium is most often found in abundance alongside the edge of the track. 

 Eriophorum angustUolium is especially noticeable in this zone near the end of the season when the 

 track is occasionally bordered by the white cotton-grass inflorescences. The frequent absence of 

 mosses is conspicuous. Typically, growth is initiated somewhat sooner in the track than on 

 adjacent tundra and occasionally a portion of the track is extremely lush as is indicated by the high 

 production values and leaf area indices. Associated with these tall, lush areas, however, is the 

 conspicuous absence of standing dead and litter. 



Additional observations on the revegetation of tracks were made on two trails at site 8. One 

 weasel trail examined was used intensively during the summer of 1962 and then closed to further 

 traffic. On drier portions of this trail, which extends for 1.8 km, vegetation within the tracks had 

 a similar appearance to that of the adjacent undisturbed areas. Regrowth had apparently been by 

 vegetative means. The barer spots were revegetated only by cryptogams, mostly mosses less than 

 1 mm high. On the wetter portions of the trail, ponds had formed due to melting of the ground ice. 

 These ponds were Vz m deep and more than 1 m across. There was no invasion by vascular plants 

 along the edges or in the ponds but some mosses were present along the edges. On a second trail, 

 which had been heavily used for 3 summers and abandoned in fall 1965, considerable thermal 

 erosion had occurred. Again a thin moss-and-lichen cover had developed. Drier, bare spots were 

 being invaded by vascular plants, through vegetative means. This revegetation extended Vz m into 

 the track, an advance of 10 cm/yr. On other portions of the trail Dupontia fiscberi had invaded at 

 an estimated rate of between 14 and 20 cm/year average. One specimen, Senecio congestus, found 

 in the track, invaded by seed. 



In conclusion, track disturbance resulted in very definite alterations of the vegetation, soil 

 and soil solution such that biological activity and primary production was stimulated. This does 

 not mean that the disturbance was good, however, for if much of a slope gradient existed there 

 likely would have been severe and detrimental soil erosiai. The results do give an indication that 

 controlled physical disturbance of the surface vegetation and peat layer might be used to stimulate 

 more vigorous vegetative growth with beneficial results. However, these conclusions must be 

 tempered until complete analysis of samples and data have been accomplished. 



Barrow Aqnatic Perturbations 



Bob Barsdate* University of Alaska 



Alex Fu University of Alaska 



Richard Prentki University of Alaska 



Bob Lewellen University of Denver 



Don Vietor USA CRREL 



Jerry Brown* USA CRREL 



Two types of aquatic perturbations were sampled in order to obtain base-line data on these 

 man-induced features. The first was the channel above and below the eroding headwall of Footprint 

 Creek. The second was a thermokarst pit formed as a result of sustained tracked vehicle activity. 



Footprint Creek and its drainage offered an excellent opportunity to investigate a stream 

 gradient perturbation. The most prominent feature of this gradient is the nearly vertical headwall 

 that erodes actively upstream during periods of spring and summer runoff. Above the headwall the 

 creek occupies a shallow swale and runs through emergent vegetation and occasional small ponds. 

 A bulldozer trench intercepts the upper drainage area and introduces runoff from the artificially 

 drained Footprint Lake basin. Above the headwall, free of suspended particles, the water is clear 

 although noticeably colored by brown organic acids. Below the headwall, the stream bed is unstable 

 and nearly devoid of vegetation, as large amounts of fine-grained sedimentary material are trans- 

 ported downstream from the headwall area. The water is highly turbid. The headwall with essen- 

 tially no flow over it is illustrated in Figure 26. 



•Principal authors. rrj 



