不同覆盖处理下西南亚高山森林土壤颗粒态有机碳的季节动态

Seasonal Dynamics of Particulate Organic Carbon in Subalpine Forest Soil in the Southwestern China

[目的]研究不同覆盖处理对西南亚高山森林土壤颗粒态有机碳动态的影响.[方法]利用均质化重装土柱在凋落物和积雪不同的土表覆盖处理下（裸土除雪BNS、裸土覆雪BS、凋落物除雪LNS、凋落物覆雪LS）进行原位培养,在不同时间采集原位培养土柱,分别测定0～10 cm和10～20 cm深度土壤颗粒态有机碳（Particulate organiccarbon,POC）含量.[结果]不同处理下土壤表层（0～10 cm）与表下层（10～20 cm） POC含量在短期内均具有一定的稳定性,但低温季节和非冻融季节含量变化显著;各处理下POC在低温季节中期高于前期和末期;效应分析显示,采样时间（温度）对POC含量影响显著,而凋落物和积雪覆盖对土壤POC含量影响不显著,但各种采样时间（温度）、覆盖和土壤深度等因素对土壤POC动态有交互作用.[结论]亚高山土壤POC主要是在低温季节前期和中期形成和积累,在非冻融季节消耗,温度因素比土表覆盖更显著影响土壤POC的季节动态.气温升高将导致高海拔土壤低温季节缩短和非冻融季节延长,可能促进高海拔土壤有机碳库中积累的大量POC消耗,使高海拔土壤成为一个潜在的碳源.

[Objective] The aim of the study was to determine seasonal dynamics of soil particulate organic carbon （POC） in the subalpine forest under different surface cover treatments. [Method] Repacked homogenized soil columns were incubated in situ under different surface cover treat- ments （bare soil without snowcover in winter, BNS; bare soil with snow in winter, BS; litter- covered soil without snowcover in winter, LNS; and litter-covered soil with snowcover in winter, LS） and soil columns were sampled in September, November, March, May, and July, respective- ly, to investigate the temporal dynamics of POC contents in both soil layers（0--10 cm and 10--20 cm）. [Results] The contents of POC were relatively stable in the short term but significant differ- ences were detected between cold season and growth season in both soil layers. POC content was higher mid in the cold season than early and later in the cold season regardless of soil layer and treatment. Repeated measures ANOVA analysis showed that soil POC content was impacted significantly by sampling date （temperature） other than soil surface cover conditions （litter or snow cover）. However, the interactions of sampling time, surface cover and soil depth had significant effects on soil POC contents. [Conclusion] Soil POC was primarily impacted by soil sampling date （soil temperature） other than surface cover conditions in the short term. Soil POC was accumula- ted early and middle in the cold season but depleted in the growing season. Therefore, warminginduced shrinkage in cold season may stimulate depletion of soil POC in subalpine forests, which could lead to a new potential carbon source.