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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 tTable 1. Landscape resistibility to coastal retreat.Group (averageretreat rate, m/yr)Irresistible(9.2)Mediumirresistible(5.5)Resistible(2.4)LandscapeunitAverageretreatrate, m/yrActive layerdepth range,mDegree ofdrainage 1Degreeof slopeinclination 2Surfacemicrorelief 3Vegetationcoverage 4Dominatingvegetation 51 14.6 >1.0 DW S H V M, Sh, He2 8.9 >1.0 D S H BV Sh, He3 8.8 >1.0 D S H, SM V He, M4 8.3 1.0 D S F B11 5.9 0.6–1.0 DW S H BV M12 4.95 0.6–1.0 DW G F V M, Se13 4.8 0.6–1.0 D G SM V M, Sh, Gr14 4.1 1.0 D G H, SM V Se, Sh, M16 2.7 >1.0 D L F BV Gr17 2.6 >1.0 D S F V Gr, He18 2.4 >1.0 D L F B19 2.3 1.0 D G F BV Gr1D – well drained, DW – poorly drained, W – wet. 2 S – steep, G – gentle, L − level. 3 F – flat, H – hummocky, T – tussocky, SM – with spotmedallions,P – polygonal. 4 B – bare surface, BV – semi-vegetated, V – fully vegetated. 5 Sh – shrubs, He – herbs, Gr – graminoids, M – moss,Se – sedge.Table 2. Average numerical score analysis of environmental controls.Groups of Environmental controls of maximum retreat ratelandscapes Dominating Vegetation coverage Degree of slope Degree of drainage Surface microreliefvegetationinclinationIrresistible 2.4 2.4 2.3 1.7 1.9Medium irresistible 1.9 2.3 2.1 2.0 1.7Resistible 1.2 1.8 1.7 1.3 1.5Scores were summarized and averaged for a group oflandscapes as shown in Table 2. Though the table is basedon expert judgment, the result expresses an expected pattern:landscape units with a higher retreat rate (Irresistible)according to field measurements show the highest numericalscore in all the cases excluding drainage factor, so we considerthis approach to give a good qualitative estimate. Analyzingthe range of average score for various environmental controlsbetween Irresistible and Resistible landscape groups, we notethat the maximum difference (2.4-1.2=1.2, Table 2) belongsto the “dominating vegetation” control, which makes thisfactor most valuable in determining the degree of resistibilityto coastal retreat. Gentle, well-drained slope, though, withmoss-shrub vegetation (landscape unit 15) belongs to thecategory of Resistible landscapes.ConclusionDominating shrubby-mossy vegetation is an indicatorof irresistibility of landscapes to maximum coastal retreat,while graminoids indicate the lowest maximum retreatrate. Geomorphological controls are less significant. Mostvaluable of the geomorphic factors is slope inclination due togravimetric effect. Microrelief features, such as hummocksand spot-medallions, increase irresistibility of landscapeunits, especially in combination with steep slopes, becausethey result from flaws in the active layer.A combination of environmental controls, even thosehaving a medium numerical score assigned by an expertjudgment each, results in a high maximum coastal retreatrate and is a reason for adding this landscape unit in thecategory of Irresistible.ReferencesKizyakov, A.I., Leibman, M.O. & Perednya, D.D. 2006.Destructive relief-forming processes at the coasts ofthe Arctic plains with tabular ground ice. KriosferaZemli X(2): 79-89 (in Russian).Melnikov, E.S. (ed.). 1983. Landscapes of Cryolithozone ofWestern-Siberian Gas Province. Novosibirsk: NaukaPublisher, 166 pp. (in Russian).Virtanen, T., Mikkola, K. & Nikula, A. 2004. Satellite imagebased vegetation classification of a large area usinglimited ground reference data: case study in the Usa Basin,NE European Russia. Polar Research 23(1): 51-66.136