Shrub decline and expansion of wetland vegetation revealed by very high resolution land cover change detection in the Siberian lowland tundra

Rúna Magnússon*, Juul Limpens, David Kleijn, Ko van Huissteden, Trofim C. Maximov, Sylvain Lobry, Monique M.P.D. Heijmans

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Vegetation change, permafrost degradation and their interactions affect greenhouse gas fluxes, hydrology and surface energy balance in Arctic ecosystems. The Arctic shows an overall “greening” trend (i.e. increased plant biomass and productivity) attributed to expansion of shrub vegetation. However, Arctic shrub dynamics show strong spatial variability and locally “browning” may be observed. Mechanistic understanding of greening and browning trends is necessary to accurately assess the response of Arctic vegetation to a changing climate. In this context, the Siberian Arctic is an understudied region. Between 2010 and 2019, increased browning (as derived from the MODIS Enhanced Vegetation Index) was observed in the Eastern Siberian Indigirka Lowlands. To support interpretation of local greening and browning dynamics, we quantified changes in land cover and transition probabilities in a representative tundra site in the Indigirka Lowlands using a timeseries of three very high resolution (VHR) (0.5 m) satellite images acquired between 2010 and 2019. Using spatiotemporal Potts model regularization, we substantially reduced classification errors related to optical and phenological inconsistencies in the image material. VHR images show that recent browning was associated with declines in shrub, lichen and tussock vegetation and increases in open water, sedge and especially Sphagnum vegetation. Observed formation and expansion of small open water bodies in shrub dominated vegetation suggests abrupt thaw of ice-rich permafrost. Transitions from open water to sedge and Sphagnum, indicate aquatic succession upon disturbance. The overall shift towards open water and wetland vegetation suggests a wetting trend, likely associated with permafrost degradation. Landsat data confirmed widespread expansion of surface water throughout the Indigirka Lowlands. However, the increase in the area of small water bodies observed in VHR data was not visible in Landsat-derived surface water data, which suggests that VHR data is essential for early detection of small-scale disturbances and associated vegetation change in permafrost ecosystems.

Original languageEnglish
Article number146877
Pages (from-to)1-16
Number of pages16
JournalScience of the Total Environment
Volume782
Early online date1 Apr 2021
DOIs
Publication statusPublished - 15 Aug 2021

Bibliographical note

Funding Information:
This work was funded by the Netherlands Polar Programme of the Dutch Research Council (NWO) [grant number ALWPP.2016.008 ]. The field campaigns supporting this work received funding from the European Union's Horizon 2020 project INTERACT [grant agreement number 730938 ]. The funding sources had no role in the conceptualization, execution or submission for publication of this study. Sylvain Lobry worked on this project during a post-doctoral position at the Laboratory of Geo-Information Science and Remote Sensing, Wageningen University, The Netherlands. We thank Sergey Karsanaev, Roman Petrov and Egor Starostin of the Institute for Biological Problems of the Cryolithozone of the Siberian Branch of the Russian Academy of Sciences, and Tatyana Stryukova and colleagues of the Regional Inspection of Nature Protection of the Allaikhovsky Region for logistic support. We thank Katrien Kurvers MSc for exploratory analysis on the satellite images. Data used for this study are available from the DANS EASY repository ( Magnússon, 2021 ), except copyrighted satellite images (see Table S1).

Funding Information:
This work was funded by the Netherlands Polar Programme of the Dutch Research Council (NWO) [grant number ALWPP.2016.008]. The field campaigns supporting this work received funding from the European Union's Horizon 2020 project INTERACT [grant agreement number 730938]. The funding sources had no role in the conceptualization, execution or submission for publication of this study. Sylvain Lobry worked on this project during a post-doctoral position at the Laboratory of Geo-Information Science and Remote Sensing, Wageningen University, The Netherlands. We thank Sergey Karsanaev, Roman Petrov and Egor Starostin of the Institute for Biological Problems of the Cryolithozone of the Siberian Branch of the Russian Academy of Sciences, and Tatyana Stryukova and colleagues of the Regional Inspection of Nature Protection of the Allaikhovsky Region for logistic support. We thank Katrien Kurvers MSc for exploratory analysis on the satellite images. Data used for this study are available from the DANS EASY repository (Magn?sson, 2021), except copyrighted satellite images (see Table S1).

Publisher Copyright:
© 2021 The Author(s)

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Keywords

  • Arctic greening
  • Land cover change
  • Permafrost
  • Potts model
  • Siberian lowland tundra
  • Vegetation succession

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