低温季节西南亚高山森林土壤可溶性有机碳动态

Dynamics of Dissolved Organic Carbon in Subalpine Forest Soil in Southwestern China during the Cold Season

作为生物有效性极高的土壤活性有机碳组分之一的土壤可溶性有机碳易受到地表覆被以及土壤水热动态等影响,其含量与动态在短期内可能产生较大变化,从而可作为土壤有机碳动态的短期指标。以我国敏感而重要土壤碳汇之一的西南亚高山森林生态系统为研究对象,通过测定不同地表覆盖处理下(积雪和凋落物)原位培养的土柱DOC含量,研究不同地表覆被下低温季节土壤DOC的动态变化。结果表明,不同处理下亚高山森林土壤DOC含量在低温季节的变化仍然显著;积雪与凋落物对土壤DOC含量的作用不同,凋落物覆盖有利于低温季节(尤其后期)土壤DOC含量升高,而积雪则抑制了凋落物对土壤DOC的增加效应。这表明对于亚高山森林生态系统,冬季积雪减少或消失,有利于土壤DOC含量升高,从而导致土壤有机碳库中的不稳定性碳库比例增加。

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.