海南岛文昌市不同森林类型土壤有机碳分布特征及其影响因素

土壤有机碳分布对于生态系统碳循环过程有重要意义,热带森林土壤存在高度空间异质性,不同森林类型下土壤有机碳的分布仍存在很大不确定性。因此,以海南岛文昌市五种森林类型的表层土壤为研究对象,探究其有机碳分布特征,并通过相关性分析、逐步回归分析和冗余分析阐明影响土壤有机碳分布的主要影响因子,结果表明:文昌市五种森林类型土壤有机碳含量范围在6.18－35.71k/kg,木麻黄人工林土壤有机碳含量最低,不利于土壤碳固存,有机碳分布表现为桉树人工林>人工混交林>次生林>相思人工林>木麻黄人工林；不同森林类型中有机碳含量变化与土壤中全氮含量、碳氮比变化一致；影响有机碳分布的主要因素为土壤全氮含量和碳氮磷化学计量比。研究结果可以为热带地区土壤碳固存及森林生态系统管理保护提供理论依据。

Characteristics of soil organic carbon distribution in different forest types and its influencing factors in Wenchang, Hainan Island

Soil organic carbon distribution is important for ecosystem carbon cycling processes. Tropical forest soils are highly spatially heterogeneous, and there is still great uncertainty in the distribution of soil organic carbon under different forest types. Therefore, the surface soils of five forest types in Wenchang, Hainan Island, were selected as the research object to investigate the characteristics of their organic carbon distribution. Correlation, stepwise regression and redundancy analyses were used to elucidate the main factors influencing the distribution of soil organic carbon. The results showed that the soil organic carbon content of the five forest types ranged from 6.18 to 35.71 k/kg, and the soil organic carbon content of the plantation forest was the lowest, which was not conducive to soil carbon sequestration. The distribution of organic carbon was as follows: Eucalyptus plantation > mixed plantation > secondary forest > Acacia plantation > Mujumbura plantation; the changes of organic carbon content in different forest types were consistent with the changes of total nitrogen content and carbon to nitrogen ratio in the soil. The main factors affecting the distribution of organic carbon were the soil total nitrogen content and the carbon to nitrogen to phosphorus stoichiometry ratio. The results of the study can provide a theoretical basis for soil carbon sequestration and forest ecosystem management and conservation in tropical regions.