Created: 2014-02-03 14:11:11
Modified: 2014-02-04 08:08:17
DESCRIPTION OF AREA CONTAINING SITE:
Site description: Flat with low-centered polygons; wet nonacidic tundra.
Vegetation communities: (1) Lower microsites, including polygon basins and troughs: Wet Eriophorurn angustifolium, Carex aquatilis, Scorpidiurn scorpioides graminoid tundra. (2) Raised microsites, including polygon rims and hummocks: Moist Eriophorum triste, Dryas integrifolia, Tomenthypnum nitens graminoid, prostrate-shrub tundra. Cover of top 5 species: Eriophorum angustifolim (28%), Scorpidium scorpioides (11%), Carex aquatilis (10%), Drepanocladus brevifolius (3%),Dryas integrifolia (3%)
Mean vegetation height: 4.1 +/- 3.9 cm
Mean live moss layer thickness: 0.8 +/- 0.7 cm
Organic layer thickness: 25 + 1.5 cm.
(Walker and Bockheim, 1995)
SAMPLING DESIGN AND METHOD:
Beginning in 1995, the active layer has been probed at least annually at the site. The procedure involves pushing a metal rod, calibrated in cm, to the point of refusal, interpreted in most cases to be the frost table. Thaw depth measurements at each site were obtained by probing at 5 m intervals along the plot’s two perpendicular and one diagonal transect, resulting in 71 points per plot per probing date.
In 1995 the site was instrumented with several OnsetTM portable data loggers connected to probe-type thermistors. Each logger/thermistor system has an effective temperature range of -50oC to +33oC and resolution of approximately 0.32oC. At each site, one thermistor was placed in a radiation shield approximately 2 m above the ground surface, and nine loggers were placed at the interface between mineral soil and organic material in various microtopographic positions within the site. Temperature measurements were collected at, 1 hr, and 2 hr intervals depending on season, and year. Details on methodology are provided in Klene et. al 2001.
Additional Climate data are also available at http://www.uaf.edu/water/projects/NorthSlope/coastal_plain/betty/betty.html
CALM USA George Washington University
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