Sjögersten Sofie, Wookey Philip A
School of Biosciences, University of Nottingham, UK.
Ambio. 2009 Feb;38(1):2-10. doi: 10.1579/0044-7447-38.1.2.
Changes in temperature and moisture resulting from climate change are likely to strongly modify the ecosystem carbon sequestration capacity in high-latitude areas, both through vegetation shifts and via direct warming effects on photosynthesis and decomposition. This paper offers a synthesis of research addressing the potential impacts of climate warming on soil processes and carbon fluxes at the forest-tundra ecotone in Scandinavia. Our results demonstrated higher rates of organic matter decomposition in mountain birch forest than in tundra heath soils, with markedly shallower organic matter horizons in the forest. Field and laboratory experiments suggest that increased temperatures are likely to increase CO2 efflux from both tundra and forest soil providing moisture availability does not become limiting for the decomposition process. Furthermore, colonization of tundra heath by mountain birch forest would increase rates of decomposition, and thus CO2 emissions, from the tundra heath soils, which currently store substantial amounts of potentially labile carbon. Mesic soils underlying both forest and tundra heath are currently weak sinks of atmospheric methane, but the strength of this sink could be increased with climate warming and/or drying.
气候变化导致的温度和湿度变化很可能通过植被变化以及对光合作用和分解作用的直接升温效应，强烈改变高纬度地区的生态系统碳固存能力。本文综合了关于气候变暖对斯堪的纳维亚森林苔原交错带土壤过程和碳通量潜在影响的研究。我们的结果表明，山地桦树林中有机质分解速率高于苔原石南荒地土壤，且森林中有机质层明显更浅。野外和实验室实验表明，如果水分供应对分解过程不构成限制，温度升高可能会增加苔原和森林土壤的二氧化碳排放通量。此外，山地桦树林在苔原石南荒地上的定殖会增加苔原石南荒地土壤的分解速率，从而增加二氧化碳排放，目前这些土壤储存了大量潜在的易分解碳。森林和苔原石南荒地之下的中生土壤目前是大气甲烷的弱汇，但随着气候变暖和/或变干，这种汇的强度可能会增加。
