海南岛热带海岸森林土壤易氧化有机碳分布规律及其对土壤因子的响应

Distribution of soil easily oxidized organic carbon and its response to soil factors in the tropical coastal forest of Hainan island,China

为了揭示热带海岸森林土壤易氧化有机碳的分布规律,探讨土壤因子对易氧化有机碳的影响,本研究利用高锰酸钾氧化-比色方法测定研究区域内不同林分类型(香蒲桃天然次生林、琼崖海棠天然次生林、椰子人工林、木麻黄人工林、大叶相思人工林)的土壤易氧化有机碳含量,采用简单相关系数法和冗余分析方法评估土壤因子对易氧化有机碳的影响。结果表明:在1 m深剖面内,土壤易氧化有机碳的变化范围为0.60~9.05 g·kg^(-1),各土层间随土壤深度的增加而降低且变化差异显著,均值表现为椰子人工林(4.36 g·kg^(-1))>琼崖海棠天然次生林(3.99 g·kg^(-1))>香蒲桃天然次生林(3.83 g·kg^(-1))>大叶相思人工林(1.29 g·kg^(-1))>木麻黄人工林(0.85 g·kg^(-1))。5种林分类型下,土壤有机碳活度均表现为随土层深度的增加显著降低,在0~20 cm土层,不同林型间均表现为木麻黄人工林>大叶相思人工林>香蒲桃天然次生林>椰子人工林>琼崖海棠天然次生林,说明木麻黄与大叶相思人工林土壤有机碳稳定性较差。EOC的分布受土壤因子(BD、SWC、pH、TN、C/N)的影响,其中,EOC与TN具有最大的正相关性,与BD具有最大的负相关。本研究揭示了海南岛热带海岸不同林地土壤碳库的敏感性和稳定性,研究了不同林分类型土壤EOC和土壤养分的关系,有助于了解热带海岸林地土壤养分状况的供应环境及碳汇响应机理,为评价热带海岸林分类型对土壤碳吸存能力的影响提供基础数据。

This study is aimed to reveal the distribution of soil easily oxidized organic carbon（EOC） in tropical coastal forest, and to evaluate the effect of soil factors on the EOC. The contents of soil easily oxidized organic carbon in five kinds of forests were determined.The name of five kinds of forests are Calophyllum inophyllum natural secondary forest（CIS）, Syzygium odoratum natural secondary forest（SOS）, Cocos nucifera planted forest（CNP）, Acacia auriculiformis planted forest（AAP）, Casuarina equisetifolia planted forest（CEP）. The results show that：（1）EOC had obvious vertical distribution characteristics, and decreased with the increase of soil depth.EOC also had significant difference in different forest land（CNP 〉 CIS 〉 SOS 〉 AAP 〉 CEP）. （2）The activity of soil organic carbon showed a significant decrease with the increase of soil depth.The sort of soil organic carbon activity is： CEP 〉 AAP 〉 SOS 〉 CNP 〉 CIS. （3）The distribution of EOC was affected by soil factors （BD, SWC, PH, TN, C/N）, among which, EOC and TN had the biggest positive correlation, and the BD had the biggest negative correlation.This study further shows that the stability of soil organic carbon in tropical coastal forests of Hainan island is relatively low.This study is helpful to understand the soil carbon storage condition and its response mechanism in tropical coastal forest land.