BLM REA CYR 2013 Current (2010s) modeled distribution of steppe bluff

Metadata Updated: November 12, 2020

Some of the CYR rasters intentionally do not align or have the same extent. These rasters were not snapped to a common raster per the authors' discretion. Please review selected rasters prior to use. These varying alignments are a result of the use of differing source data sets and all products derived from them. We recommend that users snap or align rasters as best suits their own projects. - Steppe bluffs are open, graminoid-sagebrush dominated sites that occur on steep, south-facing slopes in interior and southcentral Alaska. Steppe habitat occurs primarily on bluffs adjacent to rivers, including the Tanana, Porcupine, Copper rivers and a section of the Yukon River east of Galena. Elsewhere in Alaska, steppe habitat occurs on pingos on the Arctic Coastal Plain of Alaska, bluffs in Denali National Park, and river systems in southcentral Alaska, such as the Matanuska and Copper rivers and their tributaries. Only a small percentage of steppe bluff occurrences have been mapped. In the Central Yukon study area, 23 Steppe Bluff BpS sites have been mapped based on literature and observations. Steppe bluffs typically occupy steep (slope 30–46°), south-facing (aspect 121–225°) slopes. This topography facilitates microclimatic conditions that are divergent from nearby areas. Slopes receive greater solar radiation, which promotes considerable daily and annual temperature fluctuations, reduced snow accumulation and persistence, and high soil evaporation and transpiration. Collectively these factors create uniquely warm, dry microclimates. Such conditions are thought to inhibit forest development, resulting in a distinctive flora that hosts numerous endemic plants and supports notable insect biodiversity. The distribution model produced for the current and long-term future scenarios for the Steppe Bluff BpS had an AUC value of 0.963. Actual model performance is likely lower than indicated by the calculated AUC because MaxEnt generally overestimates model performance, does not calculate a true AUC, and increases AUC values as the relative proportion of potential unsuitable habitat increases. When results are interpreted as suitable habitat occurring where suitability score is greater than or equal to 70%, the model sensitivity is 62.5%, indicating that the model does not correctly classify 37.5% of all known steppe bluff occurrences. The predicted suitable distribution of the Porcupine River, Upper Yukon River, and Fortymile River region fits the known landscape and ecological niche of the Steppe Bluff BpS. The model is informative at a landscape scale and should be interpreted as potential suitable distribution rather than a microsite scale for absolute positive or negative occurrence. Of the environmental variables analyzed, the heat load index had the largest relative contribution to the model where it accounted for approximately 63.1% of relative contribution. Elevation was the lowest contributor with approximately 4.5% of relative contribution. Known and predicted future suitable distribution was dominant in the eastern section of the Central Yukon study area. Notable areas of current predicted suitable distribution include the Ladue River, Fortymile River District, the mountains near Volkmar Lake and the Tanana River, the Yukon River below Steven’s Village, the upper Yukon River (upriver of Circle), Salmon Village area of Yukon Flats NWR, and the Porcupine River.

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Metadata Date October 13, 2017
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 2015 (publication)
Frequency Of Update notPlanned

Metadata Source

Harvested from DOI Open Data

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Resource Type Dataset
Metadata Date October 13, 2017
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 2015 (publication)
Responsible Party Alaska Center for Conservation Science, University of Alaska Anchorage (Point of Contact)
Contact Email
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Bbox East Long -137.291054
Bbox North Lat 69.502100
Bbox South Lat 61.853561
Bbox West Long -165.110171
Coupled Resource
Frequency Of Update notPlanned
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Metadata Language
Metadata Type geospatial
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True

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