隔离降雨对杉木林土壤可溶性有机碳和微生物生物量碳的影响

摘要

通过在亚热带杉木林内设置不同隔离降雨强度试验：完全隔离降雨、隔离60％降雨、隔离20％降雨和对照（自然降雨），研究隔离降雨对0～20 cm土层可溶性有机碳（ DOC）和微生物生物量碳（MBC）含量的影响，结果表明：0～10 cm和10～20 cm土层，除完全隔离降雨处理土壤DOC峰值出现在春季外，其他处理均出现在秋季。0～10 cm土层中完全隔离降雨和隔离60％降雨处理的土壤MBC峰值出现在春季，而隔离20％降雨和对照的则出现在夏季，10～20 cm土层各处理对应的MBC最大值分别出现在春季、夏季、夏季和秋季。随着土层加深，4种处理土壤DOC、 MBC含量均显著降低。0～10 cm土层，完全隔离降雨处理的土壤DOC、隔离60％降雨土壤MBC均与土壤含水量显著正相关，杉木林土壤DOC和MBC对降水变化响应具有明显的季节性。%A field experiment was conducted to study effects of rainfall exclusion treatments ( i.e.no rainfall, 60%rainfall reduction, 20%rainfall reduction and control) on soil dissolved organic carbon ( DOC) and microbial biomass carbon ( MBC) contents at the depth of 0~20 cm in a Chinese fir for-est.Results showed that the maximum DOC content at the depth of 0~10 cm and 10~20 cm in no rainfall treatment occurred in spring , while DOC contents in other treatments peaked in autumn .The MBC contents in the 0~10 cm in treatments of no rainfall and 60%rainfall reduction were maximum in spring , while maximum MBC contents in treatments of 20% rainfall reduction and control were in summer .At 10~20 cm depth , seasonal MBC contents in the four treatments were maximum in spring , summer, summer and autumn respectively .Soil DOC and MBC contents in the four rainfall treatments all decreased with the increasing of soil depth .In the 0~10 cm, the DOC content in no rainfall treat-ment and MBC in 60%rainfall reduction treatment were both positively correlated with soil water con-tent.In conclusion, the importance of the seasonal dynamics of DOC and MBC should be noted .