K. R. Everett

Loess Ecosystems of Northern Alaska: Regional Gradient and Toposequence at Prudhoe Bay

Loess-dominated ecosystems cover {approx} 14% (11,000 km{sup 2}) of the Arctic Coastal Plain and much of the northern portion of the Arctic Foothills. Knowledge of this poorly known ecosystem is important for sound land-use planning of the expanding developments in the region and for understanding the paleoecological dynamics of eolian systems that once dominated much of northern Alaska. A conceptual alkaline-tundra toposequence includes eight common vegetation types and associated soils and vegetation downwind of the Sagavanirktok River. Properties of loess tundra important for land-use planning include: (1) its high ice content, which contributes to its susceptibility to thermokarst; (2) high salinities, which hamper revegetation efforts; and (3) presence of certain plant species such as Dryas intergrifolia, which are particularly sensitive to disturbance. The loess gradient provides a natural analogue for road dust, and extensive disturbance associated with oil-field development.

Cumulative Impacts of Oil Fields on Northern Alaskan Landscapes

Proposed further developments on Alaskas Arctic Coastal Plain raise questions about cumulative effects on arctic tundra ecosystems of development of multiple large oil fields. Maps of historical changes to the Prudhoe Bay Oil Field show indirect impacts can lag behind planned developments by many years and the total area eventually disturbed can greatly exceed the planned area of construction. For example, in the wettest parts of the oil field (flat thaw-lake plains), flooding and thermokarst covered more than twice the area directly affected by roads and other construction activities. Protecting critical wildlife habitat is the central issue for cumulative impact analysis in northern Alaska. Comprehensive landscape planning with the use of geographic information system technology and detailed geobotanical maps can help identify and protect areas of high wildlife use.

The arctic flux study: A regional view of trace gas release

Journal Of Biogeography (1995) 22, 365-374 The Al‘CtlC FIUX StUClV: a regional view Of trace gas release G. WELLER*1, F. S. CHAPIN2, K. R. EVERETT,3, J. E. HOBBIE4, D. KANE5, W. C. OECHEL6, C. L. PING7, W. S. REEBURGH8, D. WALKER9, and J. WALSH10, ILAII Science Management Ofiice, Center for Global Change, University of Alaska Fairbanks, PO Box 757740, Fairbanks, AK 99775, U.S.A. 2Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, U.S.A. 33610 Johnstown—Utica Rd., Johnstown, OH 43031, U.S.A. 4Ecosystem Center, Marine Biological Laboratory, 67 Water St., Woods Hole, MA 02543, U.S.A. 5Department of Civil Engineering, University of Alaska Fairbanks, PO Box 755900, Fairbanks, AK 99775, U.S.A. 6Biology Department, San Diego State University, San Diego, CA 92182-0001, U.S.A. 7Agriculture and Forestry Experimental Station, University of Alaska Fairbanks, 533 Fireweed, Palmer, AK 99645, U.S.A. 8Department of Geosciences, University of California Irvine, 205 Physical Sciences, Irvine, CA 92717-3100, U.S.A. 9Institute of Arctic and Alpine Research, University of Colorado, Campus Box 450, Boulder, CO 80309-0450, U.S.A. “Department of Atmospheric Sciences, University of Illinois, 105 S. Gregory Ave., Urbana, IL 6180], U.S.A. Abstract. Fluxes of trace gases from northern ecosystems represent a highly uncertain and potentially significant compo- nent of the arctic land——atmosphere system, especially in the context of greenhouse-induced climate change. The initial goal of the Arctic Flux Study (a part of NSF’s Arctic System Science Program)’ is a regional estimate of the present and future movement of materials between the land, atmosphere and ocean in the Kuparuk River basin in northern Alaska. We are measuring rates and controls of processes along a north~ south transect running from the marshy coastal plain to moun- tain valleys. Important vertical fluxes under study are the release of CO2 and CH4 from soils and water, lateral fluxes are surface water, nutrients, and organic matter. A hierarchy of measurements allow the rates and under- standing of processes to be scaled from plots to the landscape, regional, and circumarctic level. These include gas flux mea- surements in small chambers, measurements over larger areas by eddy correlation from small towers, and measurements at the landscape scale from airplane overflights. Experimental manipulations of carbon dioxide, soil moisture, nutrients and soil temperature from this and other studies give information on process controls. The distribution of plant communities has been described at several landscape-scale sites and a hier- archic GIS has been developed for the region at three scales (plot, landscape, region). Climate is measured at six sites and hydrological processes are being studied at each watershed scale. In the soils, measurements are being made of soil organic matter and active layer thickness and of availability of soil organic matter for microbial transformation into CO2 and CH4. Fluxes and process understanding have been incorporated into a hierarchy of models at different scales. These include models of regional climate nested in a GCM; of regional- and continental-scale plant productivity and carbon cycling includ- ing CO2 release under altered climates; watershed and regional models of hydrology; and surface energy budgets. After the first year of study the regional climate model has been successfully configured to the northern Alaska region. We have also measured a large release of carbon dioxide from tundra soils in all but the coldest and wettest parts of the transect. The rates from eddy correlation towers (landscape level) agree closely with rates from chambers (plot level). Observations, experimental manipulations and modelling analyses result in the prediction that the combination of warmer and drier soils is responsible for the large CO2 release. Key words. Arctic, tundra ecosystem, global warming, car- bon dioxide, methane, trace gases, modelling. INTRODUCTION Greenhouse warming in northern land areas is predicted by global climate models to be several times greater than the global mean of 1.5—4.5°C (IPCC, 1992). During the past *Corresponding author.

ROAD DUST AND ITS ENVIRONMENTAL IMPACT ON ALASKAN TAIGA AND TUNDRA

The physical and chemical characteristics and ecological consequences of road dust in arctic regions are reviewed with emphasis on recent information gathered along the Dalton Highway and the Prudhoe Bay Spine Road in northern Alaska. The primary observed ecological effects of dust are (1) early snowmelt in roadside areas due to lower albedos, resulting in a snow-free band of vegetation within 30 to 100 m of the road in early spring, which is used by waterfowl and numerous other species of wildlife; (2) a decrease in Sphagnum and other acidophilous mosses near the road; (3) an increase in many minerotrophic mosses; (4) a decrease in soil lichens, particularly species of Cladina, Peltigera, and Stereocaulon; (5) elimination of corticolous lichens near the road in areas of particularly high dust fall; (6) a general opening of the ground cover near the road and a consequent colonization of these barren surfaces by many taxa that are common on mineral-rich soils; (6) few effects on vascular plant abundance xcept in areas of very high dust, where ericaceous taxa and conifers are affected; (7) increased depth of thaw within 10 m of the road, possibly due to decreased plant cover and earlier initiation of thaw; and (8) contribution to thermokarst in roadside areas. Enhanced dust control measures should be considered, particularly where the road passes through scenic lichen woodlands, acidophilous tundra, annd in calm valleys where dust commonly is a traffic safety hazard.

Steppe Vegetation on South-Facing Slopes of Pingos, Central Arctic Coastal Plain, Alaska, U.S.A.

The hypothesized presence of large regions of grass and forb-dominated “steppe tundra” across Alaska and Siberia during the Pleistocene glacial epochs has led to a search for modern analogs. Eviden...

PINGOS OF THE PRUDHOE BAY REGION, ALASKA

Two distinctive types of small dome-shaped hills occur in the Prudhoe Bay region. One type has small basal diameters, steep side slopes, and occurs primarily in drained thaw-lake basins; the other type consists of mounds of larger diameter and commonly occurs outside modern lake basins. The U.S. Army Cold Regions Research and Engineering Laboratory drilled three of the mounds including one broad-based mound and encountered massive ice in all of them. It is thus likely that all of the steep-sided mounds and at least the larger broad-based mounds are pingos. It is clear that the largest of the broad-based mounds are neither dunes, unmodified remnants, nor highly eroded steep-sided pingos of the type common in the region today. Discriminant analysis of topographic-map data indicates that mean slope and length of the longest axis are the clearest discriminators between the two groups of mounds. The broad-based mounds are limited to older surfaces in the region and are thus likely to be quite old (< 12,000 yr). Explanations for the large size of many of the broad-based mounds and their occurrence outside lake basins will have to await detailed drilling studies.