Peatland water table elevation is measured in a well near the peatland center of each of six research watersheds and within the Bog Lake Peatland. All of the peatwell sites have Belfort Instruments (Baltimore, Maryland) model FW-1 strip chart recorders with a float and pulley system to monitor water levels (data resolution 0.3 cm).
The peatlands are vegetated with plants ranging from Sphagnum to low shrubs to mature black spruce (Picea mariana) and tamarack (Larix laricina) trees. The organic soils (peat) in the interior of the peatlands range from 1.8 m to 9.1 m in depth. Water tables are at or near the peat surface. The peat is not stable for data recorders. Therefore, shelters for the recorders are mounted on four 3.2 cm pipes anchored through the peat into the mineral soil below. A 0.3 m section of spiral auger was welded to the end of each pipe. A recorder sits on a wooden platform that is about 0.6 m x 0.9 m in dimension and 0.9-1.2 m above the peat surface. Peat below the platform was excavated to a depth of about 1.2 m. A stilling well (~0.3 m diameter galvanized pipe) was originally placed into the hole and secured to the pipes. The stilling wells have been replaced with wooden enclosures that extend into the subsurface to prevent peat from collapsing into the excavations. A float rises and falls in the stilling well with water table fluctuations and rotates the recorder pulley via a flat metal tape that is connected to a counterweight.
Peatland wells are visited weekly and recorder stripcharts are changed at that time. Every several years, elevations are measured relative to known benchmarks to determine the platform elevation in feet above mean sea level. During the weekly visits, the depth to water from the platform is determined with a tape measure and subtracted from the platform elevation. This value is the elevation of the water surface and is used to set the pen position on the chart. If the stripchart reading differed from the check value, the chart values were adjusted and notated on the charts. The starting and ending date/time and water table elevation are recorded on each stripchart.
Propane lamp heaters were added to the shelters incrementally between 1990 and 2005 to maintain an unfrozen pool for year-round operation. Before heating, ice was chipped from nearby satellite wells when the recording peatland wells were frozen and daily water levels were extrapolated from water-table recession curves (indicated with FLAG = E).If the recorder malfunctions for some reason the missing values were estimated with consideration of stream runoff and precipitation for the same time period, and from water levels in the other peatlands (indicated with FLAG = I beginning Jan 1, 2020).
The peatland water tables may quickly rise with rain or snowmelt events, but fall (recess) at a slower rate. Daily high values were read from the chart and entered into Microsoft Excel spreadsheets. All data entries were verified and data plots were observed to detect any suspicious values. The daily entries were then converted to metric units and stored in a summary spreadsheet.
Peatland water level data collection has been uninterupted since 1961 at the S1, S2 and S3 sites. Data are uninterupted since 1962 at S4 and S5. The S6 data are from 1965 to June 1974 and from April 1976 to the present. Bog Lake data are uninterupted since July 1990. All water table elevation data is presented in meters above sea level.
Study areas and methods are described in detail in the following publication:
Sebestyen, S.D., C. Dorrance, D.M. Olson, E.S. Verry, R.K. Kolka, A.E. Elling, and R. Kyllander (2011). Chapter 2: Long-Term Monitoring Sites and Trends at the Marcell Experimental Forest. In Randall K. Kolka, Stephen D. Sebestyen, Elon S. Verry, and Kenneth N. Brooks (Ed.). Peatland Biogeochemistry and Watershed Hydrology at the Marcell Experimental Forest (pp 15-71). CRC Press, Boca Raton, FL. https://www.fs.usda.gov/treesearch/pubs/37979.
