The Coastal Tundra at Barrow 25 



cm, the soils are considered Histic Pergelic Cryaquepts. Rarely is the or- 

 ganic material of sufficient thickness that Pergelic Cryohemists or the 

 very fibrous Cryofibrists can be recognized. This association of soils 

 repeats from polygon to polygon. 



On the centers of prominent high-centered polygons PergeHc Cryo- 

 saprists are found. They are the products of oxidation of Pergelic Cryo- 

 hemists of the former polygon basin. Lighter-colored Aerie Pergelic Cry- 

 aquepts are found on the coarser-textured and better-drained mineral 

 soil slopes marginal to Footprint Creek. 



The maximum thaw depths encountered across the entire Biome re- 

 search area ranged between 24 and 60 cm (Table 1-3). Thaw variation as 

 a function of microrelief showed less deviation from the mean early in 

 the season than later in the summer, when site characteristics had had 

 time to exert their full influence. However, thaw differences between 

 rims of low-centered polygons and centers of high-centered polygons de- 

 crease during the season as the tundra surface becomes generally drier. 

 Measurements of mean mid-August thaw depth from 1970 to 1974 in 10 

 control plots on the Carex-Oncophorus meadow (site 2) showed only a 

 2-cm difference between years (25.2, 26.9, 26.7, 24.7 and 24.7 cm). The 

 small difference in mean depth between summers with quite different 

 meteorological conditions indicates that the soil that remains near satu- 

 ration is subject to a relatively small mean fluctuation in thaw. However, 

 for a more diverse terrain some 4 km to the northeast. Brown (1969) 

 measured average thaw between 33 and 43 cm over the period 1962 to 

 1966. 



VEGETATION 



Sedge meadows cover about three-quarters of the Biome research 

 area (Webber 1978) (Table 1-4, Figure 1-12). The meadows are domi- 

 nated by a single species, Carex aquatilis, and commonly have only a few 

 secondary species, such as Eriophorum angustifolium, E. scheuchzeri 

 and Dupontiafisheri. They also have a large moss component consisting 

 of species of Calliergon and Drepanocladus. Lichens are a minor compo- 

 nent of these meadows (Murray 1978). Complete species nomenclature 

 for the Biome research area is given in Murray and Murray (1978). 



The most striking feature of the vegetation is that it changes char- 

 acter every few meters in response to change of microtopography and 

 drainage (Figure 1-8). The vegetation changes are best indicated by varia- 

 tions in the subordinate species, especially the mosses and grasses. Thus 

 the ubiquitous Carex aquatilis dominates the meadow vegetation types 

 which occur along a moisture gradient from dry to wet. 



Eight major vegetation types were recognized and mapped (Figure 



