土壤易氧化有机碳对西双版纳热带森林群落演替的响应

土壤易氧化有机碳（Readily oxidizable carbon,ROC）作为土壤中易被氧化且活性较高的有机碳,能够敏感反映群落植被环境与土壤环境的早期变化。为探明土壤ROC时空变化对热带森林次生演替的响应,以西双版纳热带森林不同次生演替阶段（白背桐群落、野芭蕉群落与崖豆藤群落）为研究对象,采用高锰酸钾氧化法测定并分析土壤ROC时空动态特征,探究这些变化与土壤微生物量碳及理化性质之间的相互关系。结果表明：（1）不同次生演替阶段热带森林土壤ROC含量存在显著差异,其大小顺序为：野芭蕉群落（11.38 mg/g） > 崖豆藤群落（10.5 mg/g） > 白背桐群落（9.72 mg/g）;（2）不同次生演替阶段热带森林土壤ROC含量的月份变化趋势基本一致,均表现为6月显著高于12月,且各月份间差异显著;（3）不同次生演替阶段热带森林土壤ROC含量随着土层深度增加而递减,且不同土层间差异显著;（4）土壤有机碳、微生物量碳、全氮、水解氮和铵态氮显著影响土壤ROC含量的时空变化,而pH值与土壤ROC显著负相关。因此,土壤ROC对西双版纳热带森林群落演替具有敏感的响应,土壤总有机碳、微生物量碳、全氮、水解氮、铵态氮及pH是土壤ROC时空变化的主控因素。

Response of soil readily oxidizable carbon to community succession of Xishuangbanna tropical forests

Readily oxidizable carbon (ROC) is of the most easily oxidized and sensitive carbons in soil, and sensitively responds to early environment changes in plants and soils. This study aimed to understand the spatiotemporal dynamics response of soil ROC to secondary succession in tropical forests. The spatiotemporal variation in soil ROC was measured by potassium permanganate oxidation; the relationship of soil ROC to soil microbial carbon and physiochemical properties in three secondary succession stages (Mallotus paniculatus, Musa acuminata, and Mellettia leptobotrya) of Xishuangbanna tropical forests was also analyzed. The results were as follows:(1) Soil ROC varied significantly across the three succession stages (P < 0.05), in the order of M. leptobotrya > M. acuminatan > M. paniculatus; (2) the ROC concentration had similar monthly variations in the three succession stages, with higher values observed in March and June, and lower values in September and December;(3) the ROC concentration significantly decreased down through the soil profile in the three secondary succession stages. (4) The spatiotemporal variation in soil ROC was positively affected by the soil organic carbon, microbial carbon, total nitrogen, hydrolyzable nitrogen, and NH₄⁺-N, whereas the soil ROC was negatively correlated with pH. We can conclude that soil ROC can sensitively respond to community succession in Xishuangbanna tropical forests. The spatiotemporal variation in soil ROC was attributed to the changes in factors (soil organic carbon, microbial carbon, total nitrogen, hydrolyzable nitrogen, ammonium nitrogen and soil pH) during the succession processes in Xishuangbanna tropical forests.