Site environmental, climate, water levels and temperatures, vegetation cover, and GIS change detection for assessing permafrost change in fens on the Tanana Flats, central Alaska

This data package provides data used to assess the roles of climate
extremes, ecological succession, and hydrology in repeated permafrost
aggradation and degradation in fens on the Tanana Flats, central
Alaska. The package provides data on site environmental information,
Fairbanks climate, vegetation cover, water levels and temperatures, as
well as GIS files for fen change detection. The Site data include
information on observers, locations, geomorphology, hydrology, soils,
vegetation, and disturbance. The table has numerous fields that uses
coding for class characteristics and these codes are described in the
metadata as well as compiled in the
ELS_Arctic_Boreal_Site_Soil_Veg_Code_Sheet_2020.docx. Alaska Climate
records for Fairbanks (UAF Experiment Station) from 1904 to 2019 were
acquired from the National Oceanic and Atmospheric Administration
(https://www.ncdc.noaa.gov/cdo-web/). Additional data were obtained
for the Nenana station (about 70 km southwest of Fairbanks), to fill
in small data gaps (particularly precipitation/snow depth ruler
measurements) in the Fairbanks record. We attributed the data with
fields for summer (May-September) and winter periods (November-March)
and hydrologic year (October-September) and calculated mean air
temperature, precipitation, and snow depth by seasonal period (average
of daily values) and year. The broad summer and winter periods were of
interest because warmer and wetter summers increase soil heat input
and warmer and snowier winters reduce soil heat loss. Fen hydrology
data include information on fen water level/pressure and temperatures
collected every two hours at seven sites within fens from 2011 to
2014. Vegetation composition and cover of fens, scrub, and forests was
sampled to assess effects of thermokarst on vegetation change. Plant
cover was determined by point-sampling at 100 points (including
repetitive “hits” for all layers) distributed along 5 equally spaced
rows (4-m long, 20 points per row) across the 10-m long plot. The
plots were examined for additional species and a cover of 0.1% was
assigned to all species not captured in the point sampling. Taxonomy
follows that of the Flora of Alaska provisional checklist
(https://floraofalaska.org/provisional-checklist/). The GIS files
include two ArcMap GIS shapefiles on the systematically sampled widths
of three large fen systems on the Tanana Flats. This 2019 dataset
analyses change in fen widths by measuring widths of fens evident on
high resolution imagery from 1949, 1978, 2003, and 2018.  The data
were collected in conjunction with a project to assess patterns and
rates of thermokarst in lowland ecosystems in central Alaska. The
project was funded by the U.S. Army SERDP program.