Short-term responses of winter soil respiration to snow removal in a Picea asperata forest of western Sichuan
(2.Long-Term Research Station of Alpine Forest Ecosystems and Collaborative Innovation Center of Ecological Security in the Upper Reaches of Yangtze River, Sichuan Agricultural University, Chengdu, China 611130)
【Abstract】 Aims Seasonal snowpack is one of the most important factors that control winter soil respiration in the cold biomes. The warming-induced decrease in snowpack may affect winter soil respiration of subalpine forests. The aim of this study was to explore the effect of snow removal on winter soil respiration in a Picea asperata forest. Methods A snow removal experiment was conducted in a P. asperata forest stand in western Sichuan during the winter of 2015/2016. The snow removal treatment was implemented using wooden roof method. Soil temperature, snow depth and soil respiration rate were simultaneously measured in plots of snow removal and controls during the experimental period. Important findings Compared to the control, snow removal increased the fluctuations of soil temperature. The average daily temperature of the soil surface and that at 5 cm depth was 1.12 °C and 0.34 °C lower, respectively, and the numbers of freeze-thaw cycles of the soil surface and that at 5 cm depth were increased by 39 and 12, respectively, in plots of snow removal than in the controls. The average rate of winter soil respiration and CO2 efflux was 0.52 μmol·m−2·s−1 and 88.44 g·m−2, respectively. On average, snow removal reduced soil respiration rate by 21.02% and CO2 efflux by 25.99%, respectively. More importantly, the snow effect mainly occurred in the early winter. The winter soil respiration rate had a significant exponential relationship with soil temperature. However, snow removal significantly reduced temperature sensitivity of the winter soil respiration. Our results suggested that seasonal snow reduction associated with climate change could inhibit winter soil respiration in the subalpine forests of western Sichuan, with significant implications for the carbon dynamics of the subalpine forests.
【Keywords】 subalpine forest; seasonal snowpack; snow removal; soil respiration; temperature sensitivity; forest carbon sink;
(Translated by SHI YQ)
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