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Wetland Restoration of an Exploratory Well on Alaska’s North Slope: A Learning Experience

Ecological Restoration, Vol. 22, No. 1, 2004 ISSN 1522-4740 E-ISSN 1543-4079 ©2004 by the Board of Regents of the University of Wisconsin System. Construction projects in the Arctic typically use 6-ft (2-m) thick gravel pads to insulate underlying permafrost and prevent thawing of ground ice and subsequent thaw subsidence (Figure 1). Exploration and development of oil fields on the North Slope of Alaska have required placement of more than 9,000 acres (3,640 ha) of gravel fill, including fill for roads, runways, and pads (Aeromap 2002, National Research Council 2003). Recently, the fate of Arctic tundra impacted by gravel fill has drawn the attention of United States Congress (General Accounting Office 2002, National Research Council 2003). Although a substantial amount of research has been undertaken to develop approaches to ecologically restore abandoned gravel pads (see, for example, Jorgenson and Kidd 1991, McKendrick and others 1992, Jorgenson and Joyce 1994), most of this research is not readily available to the public. This paper evaluates the effectiveness of partial removal of gravel in restoring wetlands at the North State exploratory well site in the Prudhoe Bay Oilfield. Ecological restoration of gravel pads can be accomplished by fertilizing and seeding with native grass cultivars (McKendrick 1991, Jorgenson and Joyce 1994) or planting forbs commonly found on gravel bars and ridges in the Arctic (McKendrick and others 1992). While this approach can establish plant communities, the resulting community characteristics do not closely resemble predisturbance conditions. Another approach intended to result in community characteristics more closely resembling predisturbance conditions requires complete removal of gravel fill. However, complete removal of gravel can result in substantial thaw subsidence and flooding, creating water depths beyond those at which plants grow (Jorgenson and Kidd 1991). At the North State site described in this paper, gravel was partially removed. The idea was simple: we hoped to remove enough gravel to establish pedologic and hydrologic characteristics approaching those of predisturbance conditions, while leaving enough gravel in place to limit the extent of thaw subsidence. Vegetation treatments were then applied to promote the development of a mosaic of wetland plant communities. We initiated the study in 1992 and tracked thaw subsidence, thaw depths, changes in soil characteristics, development of plant communities, and wildlife use of the site from 1993 to 2000.