CALM SITE U19 |
PEARL CREEK |
Site code |
U19 |
Site name |
Pearl Creek |
CAPS I Metadata
form |
GGD355 |
CAPS II Metadata
form |
GGD313U_18 |
Responsible for
data submission |
Karl Olson |
Email Address |
kdolson@alaska.edu |
Institution/Organization |
Bonanza Creek Long-Term
Ecological Research Program |
Location
description |
Subarctic Alaska |
Location Lat. |
64 deg. 54 min. N |
Location Lon. |
147 deg. 48 min. W |
Elevation avg.
(m) |
213 |
Methods Grid |
|
Methods Other |
Thaw Tubes, Air Temperature,
Soil temperature, Snow Cover, Precip |
Landscape
Description |
Flat west-facing valley floor |
Vegetation /Classification |
Open black spruce-white spruce
forest |
Soils (or
Material) |
Typic Historthel |
Thaw depth
measurements (year started)
|
1969 |
Air temp.
measurements (year started) |
1990 |
Snow cover
measurements (year started) |
NA |
soil temp. measurements (year started) |
1990 |
soil moisture
measurements (year started) |
2002 |
general
description of soil moisture (dry, moist, wet, saturated) |
Moist |
soil texture: if
non organic describe texture, if organic indicate thickness of organic layer
(cm) |
24-40 cm |
|
|
DESCRIPTION OF AREA CONTAINING SITE:
In 1968 three frost tubes (Rickard and
Brown, 1972, Viereck and Lev 1983) were installed in
a Mixed Spruce/Labrador Tea /Feathermoss (Picea glauca-P.mariana/Ledum groenlandicum/Hylocomium splendens) stand (Viereck et al
1993) about 4 km north of the University of Alaska Fairbanks (64 o 54’N: 147 o 49’W).
This site is in a flat area at the bottom of a west-facing slope in the Pearl
Creek valley at an elevation of 213 m. The site was burned in approximately 1914
and developed as a mixed stand of spruce. At the time of establishment of frost
tubes at the site the trees were from 50 to 60 years in age. A more detailed
description of the vegetation can be found in Viereck
and Lev 1983.
SOIL DESCRIPTION: (predominant
texture, i.e., ‘sand’, ‘gravel’, ‘peat’,
etc.):
The soil at the site is a Minto silt
loam (Reiger et al 1963). A typical Minto silt loam
has approximately 10% sand, 80% silt and 10% clay. At the Pearl Creek site the
overlying organic layer varies from 24 to 40 cm in thickness and is comprised
of an 01(F) layer, 15-20 cm in thickness over a 02 (H) humus layer about 5 cm
thick. The living moss layer averages about 5 cm thick, ranging from 2 cm under
the spruce trees to 10 cm in the densest hummocks.
SAMPLING DESIGN AND METHOD:
The
3 frost tubes and 3 snow stakes were installed in 1968 in 2 parallel lines at 2
meter spacing. To minimize disturbance at the site, for the first 15 years the
depth of thaw was recorded at irregular intervals, but weekly or bi-weekly
during critical periods of thawing and freezing and time of total freeze. For
the maximum active layer thaw the average maximum depth of thaw of the three
tubes was used. In 1981 probing of ten points along the line of the frost tube
using a metal rod was initiated. These points were at one-meter intervals and
included the three sites of the frost tubes. Following this, the average of the
ten probes, done each year at the time of maximum thaw was used to report the
annual maximum active layer thaw.
In 1990 a weather station was
established at the site and temperature sensors were established at 5,10,20,50,100,and 150 cm. A precipitation gage was also
installed at this time. In 1994 an additional sensor was installed at 200 cm. . Since
1990 readings of the temperatures, precipitation in summer, snowfall in winter,
frost tubes and soil temperatures have been recorded on a weekly basis.
Boardwalks were installed to protect the site from this increased human
traffic. In December of 2000 a 7.2 meter deep hole was bored at the site and
thermistors installed. Preliminary results indicate that the substrate is
frozen at least to 7.2 meters with the coldest temperatures being only .5
o C from 4 to 7 m.
REFERENCES:
Van Cleve, K.,
Viereck,
Viereck,
Only thaw depth data determined by
mechanical probing is reported on CALM website. For additional data contact
site investigators directly.