Abstract

Authors

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Dataset Citation

Amy Breen, Colleen Iversen, Verity Salmon, Holly VanderStel, Bob Busey, Stan Wullschleger. 2020. NGEE Arctic Plant Traits: Plant Community Composition, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, 2016. Next Generation Ecosystem Experiments Arctic Data Collection, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, USA. Dataset accessed on [INSERT_DATE] at https://doi.org/10.5440/1465967.

Dates

2016-07-18 - 2016-07-23

Geographic Location

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Methodology

Selection of plant communities in representative habitat types The Kougarok survey followed the protocol recommended by Walker et al. (2016a) for circumpolar Arctic vegetation for inclusion in the Alaska Arctic Vegetation Archive (AVA-AK; Walker et al. 2016b). In mid-June 2016, we first conducted a field reconnaissance guided by aerial imagery of the study area to assess the habitat variation at the field site. Once we were familiar with the site, we then chose to survey the six most common plant communities along the hillslope that varied in their shrub abundance, and canopy height and structure. Five replicate plots were sampled from the six habitat types at peak growing season from 18-23 July 2016. These habitat types include: 1) Dryas-lichen dwarf shrub tundra at the hillcrest, 2) Birch-Ericaceous-lichen shrub tundra predominantly on the shoulder, 3) Alder shrublands mainly on an elevational band across the backslope, 4) Willow-birch tundra mainly on the upper backslope, 5) Tussock-lichen tundra predominantly on the backslope in inter-water tracks, and 6) Alder savanna in tussock tundra in poorly developed water tracks on the footslope. Plots were chosen subjectively in areas of homogeneous and representative vegetation and varied in size from 1-25 m2 to depending on canopy structure and height. All plot corners were marked with wooden stakes for a 2.5 x 2.5 m area, except for the alder shrubland plots that were twice as large (5 x 5 m). The alder shrubland and willow-birch tundra plots were surveyed for their full plot area, while all other plots with lower stature vegetation were just a subsample (1 x 1 m) of the larger marked plot most often in the southwest corner unless otherwise noted. The southwest plot corners were georeferenced with a handheld Garmin eTrex GPS on the day of sampling to an accuracy of 3 m and marked with the plot number on a metal tag. In the fall of 2018 and 2019, plots were revisited and all four plot corners were georeferenced to improve accuracy using dGPS (Trimble R8). Two plots for each vegetation type were paired with biomass plots, most often these were the vegetation plots within the intensive stations. Species determinations and cover estimates For each plot, all plant species (vascular plants, lichens, and bryophytes) were recorded along with their percent cover in the plot as determined visually by the lead author. For plots with multiple canopies, cover estimates are absolute cover -- so the total cover for the plots can be >100%. The missing data code “NA” is used to indicate data was not measured in the field because it was not present. For example, if no tall shrubs were in a plot there is no percent cover for the tall shrub functional type thus the entry is “NA”. The species determinations made by the lead author most often follow Hulten (1968) for vascular plants. Lichen and bryophyte determinations are from an array of sources compiled by the lead author for field determination. Drs. Misha Zhurbenko (lichens) and Olga Afonina (bryophytes) verified all cryptogam determinations at the Russian Academy of Sciences in St. Petersberg, Russia. The species table includes both field determinations and accepted names according to the Panarctic Species List (Walker et al. 2016b) used by the AVA-AK. Plot descriptions, photographs and site map On the date of sampling, environmental data was also recorded for each plot (see data dictionary for the environmental table for a full list of variables). We used a standardized data form that includes both the required and recommended fields used for the AVA-AK (see ava_ak_field_datasheet_and_codes.pdf). Plot and landscape photos were taken using an iPhone. Plot photos were taken from the downslope side of the plot, so all photos were taken looking upslope. Slope and aspect were determined after sampling from a DEM (Porter et al. 2018; Arctic DEM). A map of the field site showing the locality of vegetation composition and biomass plots was created by Julian Dann at Los Alamos National Lab. Soil temperature, soil moisture, and thaw depth (soil depth) data were also collected from a subset of plots and are available in Related Datasets.

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