Sergey Loiko1,2, Nina Klimova1,3, Darya Kuzmina1, Oleg Pokrovsky1,4,5. 1. BIO-GEO-CLIM Laboratory, National Research Tomsk State University, Lenina St. 36, 634050 Tomsk, Russia. 2. Tomsk Oil and Gas Research and Design Institute (TomskNIPIneft), Prospect Mira 72, 634027 Tomsk, Russia. 3. Institute of Monitoring of Climatic and Ecological Systems Siberian Branch of the Russian Academy of Sciences (IMCES SB RAS), Academichesky ave. 10/3, 634055 Tomsk, Russia. 4. N. Laverov Federal Center for Integrated Arctic Research, Russian Academy of Sciences, Severnaya Dvina Embankment, 23, 163000 Arkhangelsk, Russia. 5. Geosciences and Environment Toulouse, UMR 5563 CNRS, 14 Avenue Edouard Belin, 31400 Toulouse, France.
Abstract
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 (<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.
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 increaclass="Chemical">siclass="Chemical">ng the iclass="Chemical">nflueclass="Chemical">nciclass="Chemical">ng greeclass="Chemical">niclass="Chemical">ng treclass="Chemical">nds of Arctic tuclass="Chemical">ndra. However, the magclass="Chemical">nitude aclass="Chemical">nd exteclass="Chemical">nt of this process remaiclass="Chemical">n poorly uclass="Chemical">nderstood. Here we characterized placlass="Chemical">nt succesclass="Chemical">n class="Chemical">sion 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 (<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.
Entities:
Keywords:
NDVI; drained thermokarst lake; khasyrey; low-Arctic tundra; plant communities; soil physical and chemical properties; western Siberia