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12 Apr 2019
12 Apr 2019
Abstract. Soil CO2 efflux-measurements represent an important component for estimating an annual carbon budget in response to changes in increasing air temperature, degradation of permafrost, and snow-covered extents in the Subarctic and Arctic. However, it is not widely known what is the effect of curstose lichen (Ochrolecia frigida) infected sphagnum moss on soil CO2 emission, despite the significant ecological function of sphagnum, and how lichen gradually causes the withering to death of intact sphagnum moss. Here, continuous soil CO2 efflux measurements by a forced diffusion (FD) chamber were investigated for intact and crustose lichen sphagnum moss covering over a tundra ecosystem of western Alaska during the growing seasons of 2015 and 2016. We found that CO2 efflux in crustose lichen during the growing season of 2016 was 14 % higher than in healthy sphagnum moss community, suggesting that temperature and soil moisture are invaluable drivers for stimulating soil CO2 efflux, regardless of the restraining functions of soil moisture over emitting soil carbon. Soil moisture does not influence soil CO2 emission in crustose lichen, reflecting a limit of ecological and thermal functions relative to intact sphagnum moss. During the growing season of 2015, there is no significant difference between soil CO2 effluxes in intact and crustose lichen sphagnum moss patches, based on a one-way ANOVA at the 95 % confidence level (p < 0.05). Considering annual soil CO2 effluxes simulated by temperature, as well as monitoring of snow depth by time-lapsed camera, average snow-covered and snow-free CO2 contributions to annual carbon budgets correspond to 28.4 % and 71.6 % in intact sphagnum moss cover, and 25.0 % and 75.0 % in a crustose lichen sphagnum moss colony, respectively. Therefore our findings demonstrate that soil CO2 emissions in the crustose lichen-infected sphagnum moss community would be steadily stimulated by a widespread outbreak of airborne plants over intact sphagnum moss, and by a rapid degradation of permafrost in response to drastic changes in climate and environment in the Subarctic and Arctic.
Yongwon Kim et al.
Yongwon Kim et al.
Yongwon Kim et al.
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