Marshall

Created: 2014-02-03 08:44:32
Modified: 2014-02-03 08:45:22

DESCRIPTION OF AREA CONTAINING SITE:

The Marshall site is located NE of the town of Marshall which is situated along the Yukon River in the Yukon-Kuskokwim Delta.  The 50m2 grid is located in an area of open tundra on the upper portion of a hill/rise in the land on the West side of the road headed towards the weather station out of town, approx. 1/3mile from split in road to the airport.  The vegetation is moist/spongy/soggy tundra with many low bush berries throughout the site. The 50mx50m grid, established in 2009, is marked with survey stakes at 10m intervals.  The grid center (N61.88, W162.06) contains continuous soil temperature & soil moisture sensors at ‘above permafrost’ & ‘just below surface’ levels.  An air temperature sensor also records on a 30 min continuous cycle.  The grid was established in 2009 through a cooperative agreement with Yukon River Inter-Tribal Watershed Council & the U.S. Geological Survey, with assistance from Ohogamiut Tribal Council’s Environmental Coordinator.

SAMPLING DESIGN AND METHOD:

The specific location of the Marshall site was selected using Traditional Ecological Knowledge of permafrost distribution and depth, followed by on-site ground truthing.

The grid consisted of 50 survey stakes at 10-meter intervals, creating a 50mx50m square grid with a maximum of 100 data points.  Active Layer measurements were taken manually every 5m.  The measurements were taken at the lowest surface level within about 0.3m of the designated point.  The "surface level" was determined to be the top of the low-lying vegetation (i.e. moss, lichen, low-bush berries). 

[CALM protocol suggests a grid size of 100mx100m, however a 50m2 grid was deemed acceptable due to difficult terrain and length of time for installation (personal communication Dr. V.Romanovsky).]

The soil climate station was established in early September 2009 and is located at grid center. The station monitors air temperature, soil temperature & soil moisture.

The HOBO micro station was installed at the grid center.  A ~30cm2 hole was dug down to the permafrost layer approx 60 cm.  After 27cm it was very difficult to maintain the hole due to “sloppy” soil conditions. One set of soil moisture and soil temperature sensors were placed just above the permafrost layer (60cm) and one set just below surface level.  Soil samples were cut from each level (2x2in cubes) to be analyzed for soil moisture content.

The HOBO pro v2 temp/ext temp sensor was installed, recording air temperature, near the grid center about one meter off the ground surface. The Hobo data logger is set to store data on 30min intervals for up to 428 days. 

GPS points were taken at the four corners of the grid, as well as the center point where the sensors were located.  Site elevation is 69m, recorded at grid center.