Ninth International Conference on Permafrost ... - IARC Research

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Relation of Active Layer Depth to Vegetation on the Central Yamal Peninsula,RussiaM.O. LeibmanEarth Cryosphere Institute SB RAS, Tyumen, RussiaH.E. EpsteinDepartment of Environmental Science, University of Virginia, USAA.V. KhomutovEarth Cryosphere Institute SB RAS, Tyumen, RussiaN.G. MoskalenkoEarth Cryosphere Institute SB RAS, Tyumen, RussiaD.A. WalkerInstitute of Arctic Biology, University of Alaska Fairbanks, USAIntroductionThe purpose of this study was to obtain ground observationsin support of remote sensing data. The normalized differencevegetation index (NDVI) and leaf area index (LAI) weremeasured within a Circumarctic Active Layer Monitoring(CALM) program grid and compared to active layer depth(ALD) measurements. Additional data on active layerproperties (soil texture and moisture content), surfacefeatures (spot-medallions, hummocks, polygonal patternand windblown hollows), vegetation complexes, organicmat thickness, and shrub height were analyzed.The study area is located on the central Yamal Peninsulain the watershed of the Se-Yakha and Mordy-Ykha Rivers.A CALM grid was placed on the top and slope of a highlydissected alluvial-lacustrine-marine plain, affected bylandslides with sandy to clayey soils.Active surface aeolian and landslide processes commonin the study area produce vast areas of bare ground. The rateof revegetation and plant succession at such sites related toclimate fluctuations was examined through repeated descriptionsof vegetation coverage and species in 1993 and 2007.Previous studies have shown that the main controls ofthe active layer dynamics are the types of surficial deposits,moisture content in the fall, thickness of organic cover,and air temperature in summer. In general, maximum ALD(1–1.2 m) is found in sands on bare surfaces or with sparsevegetation and low moisture content (up to 20%). MinimumALD (50–60 cm) is found in peat or clay deposits coveredby thick moss and with moisture contents more than 40%.MethodsThe active layer was monitored using a metal probeaccording to the procedure accepted by the CALM program(Brown et al. 2001) within a grid 100 x 100 m in 10 mincrements. Ground and vegetation characteristics wererecorded at each grid node. NDVI was measured usinga portable ASD PSII spectroradiometer, and LAI wasestimated using a LICOR-2000 plant canopy analyzer.NDVI is essentially an index of green, photosynthesizingvegetation, as it strongly depends on the absorption of redlight. LAI (as estimated by the LICOR-2000) is the total areaof aboveground plant tissue divided by the ground area thatis covered by the extent of the plant canopy. Both NDVIand LAI are highly, positively correlated with the mass ofaboveground vegetation, and this is true for Low Arctictundra vegetation (Riedel et al. 2005).A database was compiled that included ALD, NDVI, LAI,organic mat thickness, shrub height, dominant plant species,and cover of each plant community. The spatial distributionof various parameters was analyzed on a map compiled byinterpolation of numerical data between grid-nodes usingSurfer software, and field mapping of descriptive data (mapnot shown).Active layer measurements in 2007 were accompanied byvegetation descriptions and measurements at each grid-node(121 points and their vicinities were characterized in the database).The data were sorted into three categories of ALD, theaverages of all the parameters were calculated, and relationsbetween these averages were analyzed within each category.Results and DiscussionIn general, for the entire CALM grid, the higher thevegetation indices and parameters the lower the ALD(Fig. 1). This result is within the generally accepted effectof vegetation insulation on ground temperatures and ALD(Melnikov et al. 2004).Analysis of dominant plant species supports the idea thatvegetation acts as an insulating mat. Of all the plant groups,moss showed the highest negative correlation with ALD,while lichens and shrubs were more favorable for thawing(or deep thaw was favorable for lichen and shrub growth)(Fig. 2).Eight vegetation units (Table 1) were recognized withinthe grid. “Moist grass-sedge-dwarf shrub lichen-mossand green moss hummocky tundra” (#5, Table 1) is mostwidespread. Partly bare surfaces (#1, 2, 3, and 8, Table 1)are also common, though no bare nodes occurred on thewindblown sands, due to recent vegetation recovery.When the CALM grid was established in 1993, five baresurface grid-nodes occurred in windblown hollows (Leibman1998). Revegetation of windblown sands started after177
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 tAL, cm0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 1,1 1,2 1,3708090100110120Average LAIAverage NDVIMoss/lichen average coverage, decimal fractionAverage moss/lichen thickness, cmFigure 1. Relation between the active layer depth and averagevegetation indices at a CALM grid, research polygon VaskinyDachi.AL, cm7080901001101200 10 20 30 40 50 60 70 80 90Betula nanaVaccinium vitis-ideaeHylocomnium splendensThamnolia vermicularisFrequency, %Salix nummulariaAulacomnium turgidumDicranum elongatumOchrolechia frigidaFigure 2. Relation between the active layer depth and frequency ofdominant plant species at a CALM grid, research polygon VaskinyDachi.Table 1. Legend for vegetation map of the CALM grid Vaskiny Dachi.## Vegetation complex (% bare surface) Number of grid-nodes1 Dry blowout sands 02 Dry grass-prostrate dwarf shrub-green moss-lichen tundra with spot-medallions (40–60%) 243 Dry grass-prostrate dwarf shrub-green moss and green moss-lichen tundra with spotmedallions12(10–30%)4 Moist grass-dwarf shrub lichen-moss and green moss tundra 45 Moist grass-sedge-dwarf shrub lichen-moss and green moss hummocky tundra 616 Moist grass-sedge-low shrub moss tundra 67 Wet willow-cotton grass cover 98 Moist willow-sedge-grass cover (30–50%) 5considerable warming in 2000, so the observed revegetationresulted from eight years of change. Shear surfaces of twolandslides within the CALM grid were exposed during thelandslide event in 1989. Twelve grid nodes became baresurfaces following these events. A survey in 2007 showedthat seven grid nodes were entirely revegetated (100%coverage by willow-cotton grass complex, #7, Table 1), andfive grid-nodes were partly revegetated (up to 50% coverageby willow-sedge-grass complex, (#8, Table 1) in 18 years.ConclusionThe active layer depth is negatively related to both LAIand NDVI. This is potentially helpful for mapping activelayer depths, using remotely sensed vegetation indices andproducts. Organic matter coverage and thickness are alsonegatively related to active layer depth; this is especiallytrue for moss cover. Contrary to the moss species, there is anordinal relation between ALD and lichen/shrub species.Temporal patterns of vegetation dynamics on bare surfacesafter 10–18 years of revegetation result in the formationof dwarf shrub-lichen cover on dry sandy tops and gentleslopes, willow-cotton grass cover on wet landslide shearsurface sites, and willow-sedge-grass cover on moist sites.AcknowledgmentsThis research is part of the CALM project funded by theU.S. National Science Foundation (Grant No. OPP-9732051),and the Yamal Land Cover Land Use Change project of the<strong>International</strong> Polar Year (IPY) funded by NASA Grant No.NNG6GE00A.ReferencesBrown, J., Hinkel, K.M. & Nelson, F.E. 2001. TheCircumpolar Active Layer Monitoring (CALM)program: Research designs and initial results. PolarGeography 24: 165-258.Melnikov, E.S., Leibman, M.O., Moskalenko, N.G. &Vasiliev, A.A. 2004. Active layer monitoring in WestSiberia. Polar Geography 28(4): 267-285.Leibman, M.O. 1998. Active layer depth measurements inmarine saline clayey deposits of Yamal Peninsula,Russia: procedure and interpretation of results.Proceedings of the 7th Intl. <strong>Conference</strong> on Permafrost,Yellowknife, Canada, June 23–27, 1998: 635-639.Riedel, S.M., Epstein, H.E & Walker, D.A. 2005. Biotic controlsover spectral indices of arctic tundra vegetation.Intl. Journal of Remote Sensing 26: 2391-2405.178
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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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