关键词: 亚高山森林土壤, 可溶性有机碳, 土壤活性有机碳, 低温生态系统

Abstract: Soil dissolved organic carbon(DOC) is regarded as one of the most active fractions of soil organic carbon owing to its high bioavailability, and as one of early indicators of the soil organic carbon dynamics due to its susceptibility to Land-Use and Land-Cover Change(LUCC) and soil temperature and moisture fluctuations in short term. Subalpine forest soil in southwestern China, as an important and susceptible carbon sink of terrestrial ecosystem of China, was monitored to reveal the impacts of land-cover changes on soil DOC dynamics during the cold season, and DOC contents of soils sampled from soil columns incubated in situ under different treatment of surface coverage were determined. The results showed that DOC contents under different treatment were fluctuated significantly during the cold season. Snowcover and litter cover play different roles in the change of soil DOC contents, i.e., DOC contents were enhanced by litter cover, but this effect was suppressed by snowcover, especially in the later period of cold season, which suggests that soil DOC contents in subalpine forest topsoil may be improved and the proportion of soil labile carbon pool may be increased during cold season when seasonal snowcover decreases or disappears in the context of global warming in the future.

Key words: subalpine forest soil, soil dissolved organic carbon (DOC), labile organic carbon, cold ecosystem