Study Sites & Design: Caribou-Poker Creeks Research Watershed

Credit: Jeremy Jones

The Caribou-Poker Creeks Research Watershed (CPCRW) is a relatively pristine, 104 km2, basin reserved for meteorologic, hydrologic, and ecologic research, with no current human influence (other than scientific research). The CPCRW is the only research watershed in the United States located in the region of discontinuous permafrost, which comprises a large portion of Alaska and most of interior Alaska. The watershed is representative of upland headwater stream basins in subarctic Alaska. Hydro-biological research in CPCRW has several major foci including to assess the role of disturbance such as wildfire on stream ecosystems, and assess the influence of discontinuous permafrost on fresh water ecology and hydrology.

Within the CPCRW, 38% of permafrost is unstable and thawing, and at least 2% has been lost over the past century. The distribution of permafrost within the CPCRW is governed by topographic aspect and elevation. Low sun angle creates large differences in solar input and soil temperature between north- and south-facing slopes, with permafrost generally absent on south-facing slopes but present on north-facing slopes and valley bottoms. The patchy distribution of solar input and permafrost creates a mosaic of plant communities with different rates of hydrologic partitioning between ET and runoff. Vegetation types in the study watersheds are typical of the majority of vegetated areas of interior Alaska. Uplands are dominated by well-drained hardwood forests (Betula paprifera, Populus tremuloides) on south facing slopes, and black spruce (Picea mariana) with feathermoss (Pleurozium schreberi), moss (Hylocomium, others) and lichen understories on north facing slopes. Uplands also have patchy understory of alder (Alnus viridis). Valley bottoms are well defined in terms of geomorphology and vegetation (valley width ranges from 30 to 100 m). Soils in valley bottoms are typically saturated with extensive coverage of mosses (Sphagnum spp., Hylocomium) and dwarf shrubs (B. nana, Salix spp., Vaccinium uliginosum) and patchy coverage of alder (A. tenuifolia). Soils on south facing slopes are typically shallow to moderately deep Inceptisols with thin organic horizons (5 – 9 cm) and loamy texture, whereas north facing slopes and valley bottoms are typically poorly drained Gelisols with thick organic horizons (18 – 52 cm) with permafrost 45 – 60 cm below the surface. Geology of the CPCRW is dominated by quartz-mica schists, with some micaceous quartzites, garnet-mica schists, and phyllites.

Credit: Jeremy Jones

The CPCRW has discharge records of summer stream flows dating from 1978 to present, snow depths and duration since the 1970s (SNOTEL), precipitation amount and chemistry since 1993 (NADP), and stream water chemistry since the early 2000s. Headwater streams of the CPCRW generally have ice-free flow from early to mid-May through late-September/mid-October.

The entrance to the Research Watershed is located on the Steese Highway about 31 miles from Fairbanks. Access is restricted, and permission for access or to conduct research can be obtained by contacting the Site Manager, Jamie Hollingsworth.

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