Ninth International Conference on Permafrost ... - IARC Research

Vegetation of Northern West Siberia and its Response to Human-InducedDisturbancesLudmila KazantsevaEarth Cryosphere Institute SB RAS, Tyumen, RussiaThe significant influence of climate change on ecosystemdynamics was noted long ago (Koloskov 1925, Bocher1949, Timin et al. 1973, and others) However, long-termecosystem monitoring in cold regions has been carried outby few researchers (Bliss 1975, Walker 1985, Rannie 1986,Broll et al. 2003). In this connection, the results of longtermecosystem monitoring at the Nadym site, on which iscarried out the conditions of varying climatic and humaninducedimpact, can be of interest to researchers of arcticand subarctic regions.The objective of this research is to study vegetationchanges under impact of human-induced disturbances.Annual and spatial variability in the structure, speciescomposition, coverage, and frequency of plant species werestudied related to changes in seasonal thaw depth and soiltemperature.At the Nadym site located 30 km to the south of the townof Nadym (Moskalenko 2006), detailed descriptions ofvegetation on permanent plots are annually carried out, andmeasurements of seasonal thaw depth and soil temperaturesin different landscape conditions are performed.The zonal vegetation of the Nadym area is birch-larch andbirch-pine shrub-moss-lichen light forests. The significantareas are occupied by cloudberry-Labrador tea-peat mosslichenpeatlands and low shrub-sedge-moss bogs. On frostmounds meet cedar Labrador tea-lichen and Labrador tea—peat moss open woodland.Supervisions were carried out on the 10 x 10 m plotsdivided grid on meter squares. The plots are situated innatural conditions and in a route of the Nadym-Punga gaspipeline. On each such plot are 100 squares on which thevegetation was described, the soil temperature on a surfaceand on depth 20 cm was measured, and measurements ofseasonal thaw depth were carried out. In a microrelief of plotswere described hummocks and space between hummocksand pools; their surfaces were determined with the help ofrepeated leveling. Microphytocoenoses were registered ondominant species.The analysis of the received data allowed the compilationof a complete natural and disturbed plots map: spatialstructure of microphytocoenoses, microrelief, temperatureof soil surface, soil temperature on depth 20 cm, seasonalthaw depth, peat thickness, shrub height.In Figure 1, two maps of spatial structure showundisturbed and disturbed peat-mineral frost mound results.The microrelief and dominants of microphytocoenoses areshown on these maps.The vegetation of an undisturbed frost mound is morevaried and complicated. There are 3 layers here: (1) shrublayer, height up to 40 cm (Ledum palustre); (2) sedge and lowFigure 1. Spatial structure of undisturbed (1) and disturbed (2)frost mound.Microrelief: 1 – flat surface, 2 – crack, 3 – hummocks,4 – peaty hummocks, 5 - sandy hummocks, 6 - tussocks, 7 – waterDominants of microphytocoenoses.Vascular plants (on the left from line in the index): 4 – Festucaovina, 5 – Carex globularis, 6 – Juncus filiformis, 7 – Vacciniumvitis-idaea, 8 – Empetrum nigrum, 9 – Dicranum congestum, 10– Vaccinium uliginosum, 11 – Rubus chamaemorus, 12 – Ledumpalustre, 13 – Eriophorum vaginatum, 14 – Andromeda polifolia,15 – Betula nana, 16 – Pinus sibirica, 17 – Chamaedaphnecalyculata.Mosses and lichen (on the right from line in the index): 18 – Cladinastellaris, 19 – Sphagnum fuscum, 20 – Cetraria islandica, – Cetrarianigricans, 22 – Polytrichum strictum, 23 – Plerozium schreberi.127