Andrew Flat Permafrost Long-term Monitoring and Thaw Lake Assessment, Yukon-Charley Rivers National Preserve, Alaska, 2012

Wells, Aaron

ABR, Inc. — Environmental Research & Services worked with St. Mary’s University of Minnesota (SMUMN) and NPS to initiate a long-term permafrost monitoring program in Yukon Charley National Preserve (YUCH). Field surveys were conducted 16-19 August 2012. Data were collected at 23 permanent vegetation and soil Ecological Land Survey (ELS) plots and 9 permanent photo points along 4 transects (toposequences). Additionally, 2 permanent thaw transects were established for long-term monitoring. Field study methods have been documented in this report, and field data have been provided in a M.S. Access 2010 database, ThumbsPlus Version 9 photo database, and spatially (i.e. field plot locations) in an ArcGIS geodatabase. We sampled 9 terrestrial geomorphic units, the most common included bog and fen types Three aquatic geomorphic units were sampled, including Deep Connected Thaw Lake, Shallow Isolated Thaw Lake, and Thermokarst River. Young collapse scar bogs were also commonly observed in the study area. Thaw profiles at two young collapse scar bogs revealed dramatic changes in thaw depth and vegetation over relatively short distances. Based on our field data and observations, we propose that these young collapse scar bogs are an early stage in the development of floating bogs which were also common in the study area, and represent a later stage in collapse scar bog development. Twelve Viereck et al. (1992) Level IV vegetation types were sampled in the study area. The most common included the black spruce types, Open Black Spruce Forest and Black Spruce Woodland; Wet Sedge Meadow Tundra; and the bog types, including Subarctic Lowland Sedge Bog Meadow, Subarctic Lowland Sedge-Moss Bog Meadow, and Open Low Shrub Birch-Ericaceous Shrub Bog. Based on field observations, water chemistry analysis, and a time-series of aerial and satellite imagery (1954, 1984, 2006/2007) we qualitatively compared two types of thaw lakes in the study area. The two lake types included two older, mature thaw lakes and one young thaw lake as distinguished by distinctly different vegetation, water chemistry, drainage channel morphology, fish and beaver activity, and color signature in CIR imagery.

Andrew Flat Permafrost Long-term Monitoring and Thaw Lake Assessment, Yukon-Charley Rivers National Preserve, Alaska, 2012

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