1. Environmental and vegetation control on the active layer and soil temperature in an Arctic tundra ecosystem in Alaska.
- Author
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Gonzalez Martinez, Kevin J., Zona, Donatella, Biggs, Trent, Bernabe, Kristine, Sirivat, Danielle, Tenorio, Francia, and Oechel, Walter
- Subjects
TUNDRAS ,SOIL temperature ,PERMAFROST ecosystems ,EVAPORATIVE cooling ,CLIMATE sensitivity ,HEAT conduction - Abstract
Permafrost soils contain approximately twice the amount of carbon than the atmosphere, which could be released as global warming continues. Increasing global temperatures have in fact the potential to result in increased permafrost degradation, and carbon loss into the atmosphere. To properly understand the potential release of the carbon stored in permafrost soils, it is critical to understand the environmental and vegetation control on the development of active layer, the upper soil layer that thaw during the growing season in the Arctic. Arctic tundra ecosystems are dominated by mosses, which compose approximately 40 % of the vegetation, and have a critical role in regulating the heat condition into the soil. Given their importance, the role that mosses play on permafrost degradation should be investigated in more details. This study measured soil temperature together with thaw depth, a range of environmental variables, and moss thickness, to identify the most important controls on the development of the active layer across 124 plots in continuous permafrost tundra ecosystems. We found that a thicker moss layer insulated the soil and resulted in cooler temperatures deeper in the soil, despite warmer surface temperatures. A thicker moss layer was associated with a deeper depth of thaw, likely for the higher growth of mosses in the drier and warmer topographically higher elevation areas. The protective role of mosses was only relevant for the first ~3 cm of the green moss layer, suggesting that the living moss layer was more important in regulating soil temperature, possibly through a higher ability to retain water. Soil moisture was in fact an important control on surface and deeper soil temperatures, with wetter soils been associated with cooler surface temperatures because of the higher evaporative cooling, and warmer deeper temperatures likely because of the larger heat conduction to deeper soils. Overall, this study highlights the importance of a green living moss layer on soil temperature and thaw depth. Mosses are among the most vulnerable vegetation to hydrological changes, given their lack of a rooting system, and their sensitivity to climate change should be considered when predicting the response of permafrost thaw to climate change. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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