Ninth International Conference on Permafrost ... - IARC Research

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Carbon Dynamics of the Permafrost Regime, North Slope of AlaskaYongwon Kim<strong>International</strong> Arctic Research Center, University of Alaska Fairbanks, USAKeiji KushidaInstitute of Low Temperature Science, Hokkaido University, JapanMasato ShibuyaGraduate School of Agriculture, Hokkaido University, JapanHiroshi EnomotoDepartment of Civil Engineering, Kitami Institute of Technology, JapanIntroductionThe terrestrial ecosystems, including tundra and borealforest regions of the Arctic, cover a little less than 18% ofEarth’s land surface, but they contain more than 40% of allcarbon present in the terrestrial biomes (Kasischke 2000),demonstrating about one-third of the carbon sequesteredin Pan-Arctic tundra and boreal forests. High-latitudeecosystems are particularly vulnerable to climate changedue to the large carbon pools in northern latitude soils. Thesoil carbon pool estimated for the combined tundra-borealforest ranges from 21% (Raich & Schlesinger 1992) to 30%(Post et al. 1982) of the global carbon pool.Recently, Zimov et al. (2006) addressed carbonsequestration from thawing permafrost in the Arctic. Thesoils of the permafrost region of North America contain 213Gt of organic carbon—approximately 61% of the carbon inall soils of North America. The soils of the permafrost regionof North America are currently a net sink of approximately11 MtC/yr. The soils of the permafrost region of NorthAmerica have been slowly accumulating carbon for the last5–8 thousand years. More recently, increased human activityin the region has resulted in permafrost degradation and atleast localized loss of soil carbon.Considering the wide distribution of permafrost in Alaska’sNorth Slope, the observations of the fluxes of soil CO 2(e.g.,soil respiration) and CH 4, and of the soil carbon/nitrogencontents are extremely significant for a better understandingFigure 1. Microbial respiration in subalpine tundra.of soil organic carbon turnover time with the remarkableArctic climate change (ACIA 2004) on the permafrostregime of Alaska’s tundra ecosystem.Material and MethodDescription of study areaThe observation sites are shown in Kim & Tanaka (2001),which are coastal tundra (CT) near Deadhorse, uplandtundra (UT) north of Toolik Lake station, and subalpinetundra (SaT) north of the Brooks Range along the Trans-Alaska Pipeline during the growing season of 2000/2001.Flux measurements of CO 2and CH 4using chambers, soildensity, soil water content, and dominant vegetation typeand content of soil organic carbon/nitrogen in each site wereexamined. The chambers used were of two types: one madeof transparent material and the other, of nontransparentmaterial. The former is called light and the latter is darkchamber in this study.Results and DiscussionSoil respiration and CH 4fl uxSoil respiration consists of heterotrophic (microbial) androot respiration. The average fluxes of CO 2and CH 4rangedfrom -0.058±0.012 (±SE; standard error) in coastal tundrato 0.41±0.08 gCO 2-C/m 2 /d in upland tundra, and from-1.50±0.33 in subalpine tundra to 1.42±0.23 mg/CH 4-C/m 2 /din coastal tundra, respectively. The negative values of CO 2and CH 4fluxes indicate photosynthesis and atmospheric CH 4oxidation. In terms of soil carbon during the growing season,accumulated soil respiration was equivalent to 16±12 and35±24 gC/m 2 for light and dark chambers, respectively. Itis difficult to estimate seasonal carbon emission for CH 4flux due to CH 4oxidation. Gilblin et al. (1991) reportedthat the soil respiration ranged from 6 to 20 gC/m 2 in arctictundra soils during the growing season, and Oechel et al.(1997) measured soil respiration of 4.4 to 44 gC/m 2 in arctictussock and wet sedge tundra of Alaska, which is similar toour data during 2000/2001. Figure 1 shows a snapshot of theheterotrophic respiration by soil microbe of soil respirationin alpine tundra using Landsat ETM+ image analysis as wellas in situ soil respiration data.Biomass, soil carbon, and nitrogenThe average content of biomass, carbon and nitrogen,137
Ni N t h iN t e r N at i o N a l Co N f e r e N C e o N Pe r m a f r o s tScience Technology). We thank Noriyuki Tanaka, MasamiFukuda, Hitoshi Kojima, and Satoshi Tsuda for assistingwith the data compilation.Figure 2. Soil carbon content in subalpine tundra.and C/N ratio in the upper A0 layer of arctic tundra was0.13±0.07 kg/m 2 , 0.06±0.04 kgC/m 2 , 0.001±0.001 kgN/m 2 ,and 60±18 (n=30), and was 4.31±1.07 kg/m 2 , 1.33±1.12kgC/m 2 , 0.053±0.025 kgN/m 2 , and 25±3 (n=32) in the A0layer, respectively. The upper A0 layer denotes the layers ofshrubs, herbaceous plants, lichen, and moss in surface soilsof tundra and boreal forests. Figure 2 shows the soil carboncontent in the tundra of Alaska’s North Slope during thegrowing season of 2000/2001.Turnover time of soil organic carbonBy using soil carbon content and soil respiration from theground truth data, the turnover time of soil organic carbonon the permafrost regime of Alaska’s North Slope variedfrom 240 years in upland tundra to 570 years in coastaltundra during the growing season of 2000/2001. The coastaltundra is located 32 km south of Deadhorse, which is alwayssaturated by thawed uppermost permafrost water and nearto-peatsoil. Thus, it is difficult to decompose the soil organiccarbon. Raich & Schlesinger (1992) reported the turnovertime was 490 years in the overall tundra of the Arctic. Thissuggests that the soil organic carbon in tundra is highlyvulnerable to intra-tundra regime Arctic warming.ReferencesACIA (Arctic Climate Impact Assessment). 2004. Impacts ofa Warming Arctic. Cambridge: Cambridge UniversityPress, 139 pp.Gilblin, A.E., Nadelhoffer, K.J. Shaver, G.R. Laundre, J.A.& MaKerrow, A.J. 1991. Biogeochemical diversityalong a riverside toposequence in arctic Alaska.Ecological Monographs 61: 415-435.Kasishcke, E.S. 2000. Boreal Ecosystems in the globalcarbon cycle. In: E.S. Kasishcke & B.J. Stocks (eds.),Fire, Climate Change, and Carbon Cycling in theBoreal Forest. New York, NY: Springer, 19-30.Kim, Y.W. & Tanaka, N. 2001. Temporal and spatial variationof carbon dioxide flux along a latitudinal Alaskantransect. In: T. Nakazawa (ed.), Proceedings of the6 th <strong>International</strong> Carbon Dioxide <strong>Conference</strong> Sendai,Japan: 465-468.Oechel, W.C., Vourlitis, G.L. & Hastings, S.J. 1997. Coldseason CO 2emission from arctic soils. GlobalBiogeochemical Cycles 11: 163-172.Post, W.M., Emanuel, W.R. Zinke, P.J. & Stangenberger,A.G. 1982. Soil carbon pools and world life zone.Nature 298: 156-159.Raich, J.W. & Schlesinger, W.H. 1992. The global carbondioxide flux in soil respiration and its relationship tovegetation and climate. Tellus 44: 81-99.Zimov, S.A., Schuur, E.A.G. & Chapin, F.S III. 2006.Permafrost and the global carbon budget. Science312: 1612-1613.Implication for regional carbon budgetThe regional carbon budget in the permafrost regime ofAlaska tundra was 0.034±0.025 GtC/season for the lightchamber, and 0.074±0.050 GtC/season for the dark chamberduring the growing season, respectively, based on 207,000km 2 of the Alaska tundra area including 73,600 km 2 insubalpine, 62,400 km 2 in the Arctic Foothills, and 71,000km 2 in the Arctic Coastal Plain. Those are comparable with0.004 GtC/season in wet sedge and 0.040 GtC/season in thetussock of Alaska’s tundra (Oechel et al. 1997).AcknowledgmentsThis work was funded by the INIS (IARC-NASDAInformation System) and IJIS (IARC-JAXA InformationSystem) projects and in part by the JAMSTEC (Japan Marine138
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ContentsPreface ...................
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Mapping and Modeling the Distributi
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Satellite Observations of Frozen Gr
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xiiIce Wedge Thermal Regime in Nort
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xivPermafrost Response to Dynamics
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NICOP SponsorsUniversitiesUniversit
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Deep Permafrost Studies at the Lupi
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Effect of Fire on Pond Dynamics in
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Cryological Status of Russian Soils
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Acoustical Surveys of Methane Plume
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Permafrost Delineation Near Fairban
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Preparatory Work for a Permanent Ge
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A Provisional Soil Map of the Trans
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Martian Permafrost Depths from Orbi
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Time Series Analyses of Active Micr
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Impact of Permafrost Degradation on
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DC Resistivity Soundings Across a P
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Modeling Thermal and Moisture Regim
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A Provisional Permafrost Map of the
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Alpine Permafrost Distribution at M
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Cryogenic Formations of the Caucasu
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Modeling Potential Climatic Change
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A Hypothesis: A Condition of Growth
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Modeled Continual Surface Water Sto
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Freeze/Thaw Properties of Tundra So
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Discontinuous Permafrost Distributi
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Thermal Regime Within an Arctic Was
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Seasonal and Interannual Variabilit
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Twelve-Year Thaw Progression Data f
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Continued Permafrost Warming in Nor
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Landsliding Following Forest Fire o
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A Permafrost Model Incorporating Dy
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Seasonal Sources of Soil Respiratio
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Greenland Permafrost Temperature Si
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The Importance of Snow Cover Evolut
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The Account of Long-Term Air Temper
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The Combined Isotopic Analysis of L
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Adaptating and Managing Nunavik’s
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Human Experience of Cryospheric Cha
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HiRISE Observations of Fractured Mo
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A Soil Freeze-Thaw Model Through th
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Mapping and Modeling the Distributi
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First Results of Ground Surface Tem
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Historical Changes in the Seasonall
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Rock Glaciers in the Kåfjord Area,
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Snowpack Evolution on Permafrost, N
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Climate Change in Permafrost Region
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Maximizing Construction Season in a
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Pleistocene Sand-Wedge, Composite-W
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370Huang, B. 339Hugelius, G. 105, 1
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