C. L. Ping

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.

The Gelisol Order in Soil Taxonomy

Although Soil Taxonomy attempts to account for all the soils in the world, taxa for permafrost regions of the world did not receive adequate attention until recently. This can be attributed to the low human population of permafrost regions and the limited suitability for traditional cultivated agriculture.

Soils of Alaska: LRRs W1, W2, X1, X2, and Y

Alaska covers 1,508,120 km2, about 25 % of the contiguous USA. Alaska is organized into three Land Resource Regions (LRRs): Southern and Aleutian Alaska (W1, W2), Interior and Western Alaska (X1, X2), and Northern Alaska (Y). The soil moisture regimes range from subhumid and humid in northern, interior, and western Alaska to humid and perhumid in southern Alaska. The soil temperature regime ranges from cryic in southern Alaska to pergelic in northern Alaska. Northern Alaska has continuous permafrost, and thus, the soils are dominantly Gelisols formed under tundra with gelic Inceptisols and Entisols in areas shallow to bedrock and along streams. Very small areas of gelic Mollisols are found on well-drained uplands with calcareous parent materials. Interior and Western Alaska are in the zone of discontinuous permafrost . Gelisols dominate northerly slopes under black spruce forest and peatlands. Inceptisols dominate southerly slopes and well-drained uplands under white spruce and deciduous forests. Histels or Histic Gelisols dominate poorly drained lowlands and depressions. In southern and western Alaska, moderately leached Spodosols form in volcanic ash and glacial deposits under conifer forests, and Andisols form under herbaceous and grassy vegetation. Histosols form in extensive peatlands in southern Alaska. There are limited areas in Interior and Southern Alaska under cultivation for grains, hay, and vegetables. Urban use of land is limited because of small population in the state. Most lands are in native forest and rangelands supporting wildlife habitat.