Integrated terrain unit mapping on the Beaufort Coastal Plain, North Slope, Alaska, USA

Abstract

Integrated Terrain Unit (ITU) mapping is a technique used to develop maps depicting specific ecosystem services and landscape sensitivity measures useful for land-use planning and sampling designs for spatially stratified studies. Here we describe ITU classifications, mapping techniques, and geospatial products developed from 1992 to 2018 for arctic tundra in northern Alaska in areas of ongoing oil production and exploration. We used data from 1779 field plots to classify and map geomorphology, surface form, vegetation, and disturbance history. We then derived map products for ecotypes, wildlife habitats, and U.S. National Wetland Inventory (NWI) wetlands by aggregating functionally similar ITU combinations. We evaluated the extent to which ground conditions may have changed in older portions of the ITU mapping using a map of Landsat-observed trends in Normalized Difference Vegetation Index (NDVI) for 1985–2012. The cumulative result of 26 years of study is a 3532.4 km2 area of ITU mapping. The ITU code combinations were aggregated into 66 map ecotypes, 34 wildlife habitats, and 18 wetland classes. Most of the mapping area (65.4%) experienced no significant trend in vegetation greenness. Nearly all of the remaining area (34.6%) exhibited an increase in greenness. The ITU mapping provides a baseline for monitoring future change against a backdrop of climate change and ongoing industrial activity. The map products serve as proxies for important subsurface characteristics in permafrost landscapes, and have facilitated seminal studies of landscape development and change in arctic Alaska.