Cape Rogozny

Created: 2014-01-24 13:09:23
Modified: 2014-01-27 12:23:21

SITE DESCRIPTION

The grid “Cape Rogozhny”, 100x100 m, is located on Lower-Anadyr (Nizhneanadyrskaya) Lowland at the northern coast of Onemen bay (64°47¢ North and 176°58¢ East). Relief of the area is hilly plain with altitudes 5 to 30 m above the water level in the Bay. CALM grid is set at the flat hilltop slightly (at 0-3o) inclined southwestward. The surface is represented by typical hummocky-moss tundra. Hummocks are formed of cotton grass (Erioophorum vaginatum) dominating throughout the plain. Hummock height is 15-20 cm. They cover 60 to 70% of the surface, the rest occupied by inter-hummock depressions filled mostly by green and bog mosses (Sphagnum sp.sp.) with admixture of lichens. Coverage of the dwarf shrubs within the grid is 30-40 %; coverage of green moss is 20-30 % and of lichens – 5 to 10%. Main producer of ground-level phytomass is cotton grass.

The grid is located in the area of transition from moderately-continental to marine climate subzone of the SubArctic climatic zone. Mean annual air temperature at Anadyr weather station (30 km from the grid) is -7,7oС, mean annual precipitation is 312 mm.

The hydrochemical conditions of the grid in many respects are instituted by closeness of marine coast. The type of atmospheric precipitation here is transitional from maritime to continental. Rain and thawed snow water are of chloride-hydrocarbon-sodium type with mineralization up to 45 mg/l. At inflow of thawed and rain waters into the active layer, they get saturated by ions of calcium, magnesium and hydrocarbonate, the mineralization rise up to 80-88 mg/l.

The grid is located in the continuous permafrost area. Taliks of hydrogenous type are found only below the Onemen Bay and large lakes. Mean annual ground temperature is about –5oC, the permafrost thickness is up to 150 m. Frost cracks and ice-wedge, and spot-medallion formation are periglacial features developed within the grid. At the adjacent area, the coastal processes are widespread: coastal thermoerosion, thermocircues connected with massive ground ice occurrence. Cryolithological structure of permafrost is variable. Immediately beneath the active layer modern and Holocene ice wedges are lying, up to 2 m wide and up to 3 m high. In fine-grained sands of Late-Pleistocene age syngenetic ice wedges are tracked up to 2 m in width, with vertical expansion up to 20 m. Besides, the syngenetic sandy and sandy-ice wedges are observed. In the lower stratigraphic glacial complex massive ground ice is widely distributed.

SAMPLING DESIGN AND METHOD:

Permanent 100x100 m grids have been established, with 10-m intervals between grid nodes. Thaw depths were determined at each grid node (121) using a steel rod. The measurements of the active-layer thickness were performed in inter-hummock depressions according to the CALM procedure from 1994 to present.  At the site a surface quality of microhabitats such as tundra, vehicle tracks, frost boils etc. was estimated. The site is supplied with a temperature data-loggers measuring air and soil temperatures to the depth of 100 cm but measurements are irregular