Site code


Site name

Old Man Grid

CAPS I Metadata form


CAPS II Metadata form


Site Photograph


Responsible for data submission

Brian Charlton

Email Address



Bonanza Creek Long-Term Ecological Research Program

Location description

Subarctic Alaska

Location Lat.

65 deg. 6 min. N

Location Lon.

148 deg. 03 min. W

Elevation avg. (m)


Methods Grid


Methods Other

20 m transect, Air Temperature, Soil temperature

Landscape Description

Foot of long west-facing slope

Vegetation /Classification

Open black spruce forest

Soils (or Material)

Histic Cryaquept

Thaw depth measurements (year started)                


Air temp. measurements (year started)


Snow cover measurements (year started)


soil temp. measurements (year started)


soil moisture measurements (year started)


general description of soil moisture (dry, moist, wet, saturated)


soil texture: if non organic describe texture, if organic indicate thickness of organic layer (cm)

silt loam (a Histic Cryaquept (USDA 1975)



The Wickersham CALM site was established as part of a major fire-effects study conducted by the Institute of Northern Forestry following the 1971 Wickersham Fire.

As part of these studies a series of thaw probe lines were established to follow the changes in the active layer as a result of the fire and fireline construction. Details of the fire and related studies were presented by Viereck and Dyrness (1979). The data for the Wickersham CALM site comes from an undisturbed black spruce stand that was established as a “control” for the studies of active layer changes in the burned and fireline areas.

The Wickersham site is approximately 50 km northwest of Fairbanks and adjacent to the Elliot Highway. (65 o 10’N: 147 o 54’W) The probe line is at an elevation of 335 m near the foot of a long west-facing slope. The vegetation along the probe line is an open black spruce forest type (Open Picea mariana/Ledum groenlandicum/Sphagnum spp-Cladonia spp community) (Viereck et al 1993). The black spruce have a density of 1240 trees/ha and 45% canopy cover. Average diameter of the trees in 1971 was only 5.2 cm. A detailed description of the vegetation at the site can be found in Viereck, 1982.


SOIL DESCRIPTION: (predominant texture, i.e., ‘sand’, ‘gravel’, ‘peat’, etc.):

The soil at the site is a Saulicch silt loam (a Histic Cryaquept (USDA 1975). These are poorly drained soils formed of a silty loam more than 75 cm in depth with a shallow active layer. There is a moss-litter layer (01 and 02) of 25 to 30 cm underlain by approximately 10 cm of a dark grayish-brown silty loam A horizon over a frozen C horizon of olive-gray silty loam.



A probe line 20 meters long was established parallel to the slope: 10 probing sites at 2-meter intervals were permanently marked along the line. A trail was established below the line to avoid disturbance of the vegetation at each of the probe sites.  For the first four years of the study the active layer was measured at two-week intervals. Starting in 1975 soil temperatures were also taken at two-week intervals at depths of 5, 10, 20, and 50 cm with a steel probe with a thermistors at the tip. In 1978 a set of thermistors was installed near one end of the probe line at depths of 5, 10, 20, 50, and 90 cm and were read weekly or biweekly. In addition, in October of 1978 a thermograph and weather station were installed at the site to record air temperatures. Snow depth was measured throughout the winter using two permanent snow poles.  These weekly observations were continued through October of 1983. After that the active layer was measured at the ten points along the probe line once a year, usually in mid September.



Viereck, L. A., Effects of fire and firelines on active layer thickness and soil temperatures in interior Alaska, in Proceedings of the 4th Canadian Permafrost Conference, The Roger J. E. Brown Memorial Volume, pp. 123– 134, Natl. Res. Counc. of Can., Ottawa, Ont., Canada,1982.

Viereck, L.A. and Dyrness, C.T. 1979. Ecological effects of the Wickersham Dome fire near Fairbanks, Alaska. USDA Forest Service, Pacific Northwest Forest and Range Experiment Station. General Technical Report PNW-90, 71 pp.

Viereck, L.A., Werdin-Pfisterer, N.R., Adams, P.A., Yoshikawa, K. 2008. Effect of wildfire and fireline construction on the annual depth of thaw in a black spruce permafrost forest in interior Alaska: a 36-year record of recovery. Proceedings of the Ninth International Conference on Permafrost, University of Alaska Fairbanks, June 29 - July 3, 2008: 1845-1850.


Only thaw depth data determined by mechanical probing is reported on CALM website. For additional data contact site investigators directly

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