南亚热带不同红锥混交林土壤碳库稳定性与碳库管理指数变化

The Change of Soil Carbon Stabilization and Carbon Management Index in Different Mixed Plantations of Castanopsis hystrix in Subtropical Area of South China

[目的]研究不同类型红锥混交林土壤有机碳库及其碳库稳定性特征,以期为南亚热带不同红锥混交林碳平衡过程的评估和混交模式的筛选提供理论依据。[方法]本研究以南亚热带红锥人工纯林(HC)、红锥+湿地松人工混交林(HS)、红锥+火力楠人工混交林(HH)、红锥+米老排人工混交林(HM)为研究对象,分析不同林分类型土壤有机碳(SOC)、易氧化有机碳(EOC)、颗粒有机碳(POC)、溶解性有机碳(DOC)和微生物生物量碳(MBC)含量及碳库管理指数(CMI)的变化。[结果]4种林分类型的SOC、EOC、POC、DOC、MBC含量随着土层深度的增加而降低;SOC与EOC、POC、MBC含量呈极显著正相关(P<0.01),且与POC的相关系数最大,不同林分间SOC含量均表现为:HM>HH>HS>HC,且0~20 cm土层与0~40 cm土层的变化一致;4种林分类型0~40 cm土层的CMI表现为:HM>HH>HC>HS,且20~40 cm土层的CMI变化与0~40 cm土层的变化一致。[结论]4种林分类型SOC、EOC、POC、DOC、MBC含量主要受林分表层土的影响,CMI主要受林分下层土的影响,POC含量与SOC关系最为密切;红锥阔叶混交林较红锥针阔混交林更能提高土壤肥力,改善土壤质地,且HM的阔叶混交模式土壤碳库质量最高,在有机碳和活性碳增加的同时也有助于惰性碳的积累及碳库的稳定性。

[Objective] To study the soil organic carbon pool of different plantations of Castanopsis hystrix mixed forest and its stability in order to provide reference for the evaluation of carbon balance process and the selection of mixed models of C. hystrix mixed plantations in subtropics of south China. [Method] The C. hystrix pure forest(HC), C. hystrix + Pinus elliottii mixed forest(HS), C. hystrix + Michelia macclurei mixed forest(HH), C. hystrix +Mytilaria laosensis mixed forest(HM) were used as trial objects in this study, and the changes of soil organic carbon(SOC), easily oxidizable carbon(EOC), particle organic carbon(POC), dissolved organic carbon(DOC), microbial biomass carbon(MBC)and carbon pool management index(CMI) of different mixed plantations were analyzed.[Result] The contents of SOC, EOC, POC, DOC, and MBC decreased with the increase of soil depth in the four kinds of mixed plantations. SOC had a significant positive correlation with EOC, POC, and MBC(P<0.01), and the correlation coefficient between SOC and POC was the largest. The order of SOC content was HM>HH> HS>HC among different stands, and the change of 0-20 cm soil layer was consistent with that of the whole stand(0-40 cm soil layer). The change of CMI in 20-40 cm soil layer was consistent with that of the whole stand, and the order was HM>HH>HC>HS. [Conclusion] The contents of SOC, EOC, POC, DOC and MBC are mainly affected by the surface soil, CMI is mainly affected by the subsoil, and the POC content is most closely related with SOC in the four mixed plantations. The C. hystrix broadleaved mixed forests can improve soil fertility and soil quality, and the broadleaved mixed model of HM has the highest soil carbon pool quality, with the increase of organic carbon and activated carbon, it also contributes to the accumulation of inert carbon and the stability of carbon pool.