Lake Drainage in Permafrost Regions Produces Variable Plant Communities of High Biomass and Productivity

Abstract

<jats:p>Climate warming, increased precipitation, and permafrost thaw in the Arctic are accompanied by an increase in the frequency of full or partial drainage of thermokarst lakes. After lake drainage, highly productive plant communities on nutrient-rich sediments may develop, thus increasing the influencing greening trends of Arctic tundra. However, the magnitude and extent of this process remain poorly understood. Here we characterized plant succession and productivity along a chronosequence of eight drained thermokarst lakes (khasyreys), located in the low-Arctic tundra of the Western Siberian Lowland (WSL), the largest permafrost peatland in the world. Based on a combination of satellite imagery, archive mapping, and radiocarbon dating, we distinguished early (&lt;50 years), mid (50–200 years), and late (200–2000 years) ecosystem stages depending on the age of drainage. In 48 sites within the different aged khasyreys, we measured plant phytomass and productivity, satellite-derived NDVImax, species composition, soil chemistry including nutrients, and plant elementary composition. The annual aboveground net primary productivity of the early and mid khasyrey ranged from 1134 and 660 g·m−2·y−1, which is two to nine times higher than that of the surrounding tundra. Late stages exhibited three to five times lower plant productivity and these ecosystems were distinctly different from early and mid-stages in terms of peat thickness and pools of soil nitrogen and potassium. We conclude that the main driving factor of the vegetation succession in the khasyreys is the accumulation of peat and the permafrost aggradation. The soil nutrient depletion occurs simultaneously with a decrease in the thickness of the active layer and an increase in the thickness of the peat. The early and mid khasyreys may provide a substantial contribution to the observed greening of the WSL low-Arctic tundra.</jats:p>

Plant Organic Matter in Palsa and Khasyrei Type Mires: Direct Observations in West Siberian Sub-Arctic

“…In West Siberian Arctic, the above-ground fraction of NPP (ANP) was found as much as 1134 g m −2 yr −1 at some early stages of formations of khasyrei ecosystems; then, the ANP drops to 660 ± 292 g m −2 yr −1 at the mature stage of khasyrei formation, as shown in Loiko et al [32]. Our study in the northern taiga of Western Siberia suggests that the below-ground fraction of NPP (BNP) accounts for about 60% of the total NPP in mire ecosystems.…”

“…Consequently, it becomes important to assess ongoing changes in the plant organic matter, also related to land cover changes in different geographical locations of Siberian sub-Arctic. To date, there are relatively few assessments based on direct measurements of the plant biomass and net primary production (NPP) available in published sources [23,24,32,33].…”

From permafrost soil to thermokarst lake sediment: A view from C:N:P stoichiometry

“…Previously locked organic materials in frozen soil are sealed underwater and part of the organic carbon is released into the atmosphere mainly in the form of CH 4 (Zimov et al, 1997;Heslop et al, 2020). Surrounding permafrost soil and thermokarst lake sediments are two distinct fates of pristine permafrost during thermokarst processes, which have been intensified by climate warming (Audry et al, 2011;Loiko et al, 2020;Manasypov et al, 2022). As a result of persistent and accelerating climate warming, a large number of new thermokarst lakes are formed and the old ones are expanding in coverage (Luo et al, 2015;Veremeeva et al, 2021), indicating considerable transformation from permafrost soil to thermokarst lake sediment.…”

A Pixel-Based Vegetation Greenness Trend Analysis over the Russian Tundra with All Available Landsat Data from 1984 to 2018

“…However, the shrub expansion has been spatially uneven over the Arctic because of deer grazing [7,8]. Additionally, the appearance of highly productive herbaceous plant communities in the basins of drained thermokarst lakes can also have a significant effect on the greening of the tundra [18][19][20]. Thermokarst activities also play an important role in the Arctic greening over ice-rich permafrost where an abrupt thaw has taken place [21,22].…”

“…Thermokarst activities also play an important role in the Arctic greening over ice-rich permafrost where an abrupt thaw has taken place [21,22]. The thawing permafrost brings in soil fertility [18]; significant reserves of nutrients have been found in frozen bogs, which then enter floodplains and drained lakes during thawing as a result of increased biological productivity [23]. Ukraintseva et al [24] also discovered that there was an increase in the growth of willow bushes on outcrops of more saline marine rocks.…”