热带海岸防护林土壤活性有机碳分布特征:人工林与天然次生林的比较

本研究旨在比较热带海岸天然次生林与人工林土壤活性有机碳的差异,从而提高沿海防护林土壤有机碳库的存储能力和维持土壤碳平衡提供理论依据。选取海南岛沿海防护林中典型的2种人工林和2种天然次生林作为研究对象,通过测定土壤活性有机碳及养分含量,对热带海岸天然次生林与人工林土壤有机碳的积累能力及土壤养分与有机碳相关性的差异进行分析。结果表明:(1)该研究区4种林分土壤总有机碳、轻组有机碳和易氧化有机碳均表现为琼崖海棠天然次生林香蒲桃天然次生林大叶相思人工林木麻黄人工林;(2)4种林分土壤轻组有机碳占总有机碳比例以天然次生林最高,而人工林则具有更低的轻组有机碳分配比例;反之,人工林的土壤易氧化有机碳占总有机碳比例显著高于天然次生林;(3)4种林分的土壤活性有机碳与土壤全氮、土壤容重相关性显著,此外,2种人工林林地土壤活性有机碳与土壤含水量、pH、碳氮比同样具有相关性。相关性分析结果表明,人工林土壤活性有机碳与土壤各因子的相关性较天然次生林更为密切。这说明热带海岸林地土壤碳含量总体较低,与人工林相比,天然次生林土壤有机碳具有较大稳定性。

Distribution Characteristics of Soil Active Organic Carbon of Coastal Protective Forest in the Tropics: Comparison of Plantation and Natural Forest

The analysis of the differences of soil active organic carbon (AOC) in natural forest and plantation was aimed to improve the storage capacity of the soil organic carbon storage and to provide theoretical basis for maintaining the balance of soil carbon.Respectively in the four forest types of Calophyllum inophyllum natural secondary forest,Syzygium odoratum natural secondary forest,Acacia auriculiformis planted forest,Casuarina equisetifolia planted forest in tropical coastal of Hainan province,the soil AOC and nutrient reserves were determined in order to analyze the differences of the correlations between soil nutrient and AOC and the accumulation of AOC influencing factors.The results showed:(1) The total organic carbon (TOC),light fraction organic carbon (LFOC) and easily-oxidized carbon (EOC) of the forest soils in the study area was Calophyllum inophyllum natural secondary forest ＞Syzygium odoratum natural secondary forest＞Acacia auriculiformis planted forest ＞Casuarina equisetifolia planted forest.(2) The highest soil LFOC to TOC ratio was obtained for natural forest.In contrast,lower soil LFOC to TOC ratio was observed for plantation.However,the soil EOC accounted for SOC ratio in plantation was significantly higher than the natural forest.(3) The correlation analysis between the four forests types showed that the soil active organic content was strongly correlated with soil total nitrogen,and soil bulk density.The same was with soil water content,soil pH,soil C/N of correlation in plantation.Correlation analysis results showed that the plantation soil organic carbon was closely related to soil nutrient.The results showed that the soil carbon content in the tropical forest coast was generally low,compared with the plantation,the soil organic carbon in secondary forest with higher stability.