Regional and landscape-scale variability of Landsat-observed vegetation dynamics in northwest Siberian tundra

摘要: Widespread increases in Arctic tundra productivity have been documented for decades using coarse-scale satellite observations, but finer-scale observations indicate that changes very uneven, with a high degree of landscape- and regional-scale heterogeneity. Here we analyze time-series the Normalized Difference Vegetation Index (NDVI) observed by Landsat (1984–2012), to assess variability vegetation dynamics northwest Siberian Low Arctic, little-studied region varied soils, landscape histories, permafrost attributes. We also estimate spatio-temporal rates land-cover change associated expansion tall alder (Alnus) shrublands, integrating very-high-resolution imagery dating mid-1960s. compiled eleven widely-distributed landscapes, performed linear regression NDVI values on per-pixel basis. found positive net trends (‘greening’) nine landscapes. Net greening occurred shrublands all strong tended correspond developed since 1960s. Much spatial within landscapes was linked physiography attributes, while between-landscape largely corresponded differences surficial geology. conclude continued are likely upland fine-textured, cryoturbated soils; these areas currently tend support discontinuous cover, highly susceptible rapid as well development shrublands.