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土地利用变化对土壤有机碳(SOC)的影响是全球碳循环研究的重要内容。本研究在福建漳江口红树林保护区采集红树林湿地、旱地(红树林湿地转变而来)和水田(长期种植水稻)3种土壤,测定土壤有机碳及其组分的含量变化。结果表明:红树林土壤总有机碳含量分别高于旱地土壤29.50%和水田土壤19.56%,而水田土壤有机碳含量高于旱地土壤。在湿地转变为旱地后,可溶性有机碳(DOC)、微生物生物量碳(MBC)和矿质结合有机碳(MOC)分别增加了40.39%、248.43%和144.00%,但重组有机碳(HFOC)、轻组有机碳(LFOC)和粗颗粒有机碳(CPOC)则分别下降了20.91%、46.44%和36.58%。水田土壤有机碳各组分含量均高于旱地土壤,但仅有MBC、FPOC和MOC含量高于湿地土壤。3种土地利用类型的土壤有机碳各组分含量的分配比例与其有机碳含量的规律一致。相关分析表明,3种土壤的有机碳组分中HFOC、LFOC、CPOC、MOC与SOC具有显著的相关关系,可以用来指示SOC的动态变化。这些结果说明,红树林湿地经人为垦殖后土壤SOC显著流失,但合理的耕作管理会使农田土壤具有更大的固碳潜力。
The impact of land use change on soil organic carbon (SOC) is an important part of the global carbon cycle research. In this study, mangrove wetlands, dry land (mangrove wetlands transformed) and paddy fields (long-term planted rice) were collected from the Zhangjiangkou Mangrove Nature Reserve in Fujian Province to determine the changes of soil organic carbon and its components. The results showed that total organic carbon content in mangroves soil was higher than that in dry land by 29.50% and paddy soil by 19.56%, respectively, while paddy soil organic carbon content was higher than dryland soil. The DOC, MBC and MOC increased by 40.39%, 248.43% and 144.00% respectively after wetland was converted to dry land, but the contents of recombinant organic carbon (HFOC), light The contents of LFOC and CPOC decreased by 20.91%, 46.44% and 36.58% respectively. Soil organic carbon content in paddy field was higher than that in dryland soil, but only MBC, FPOC and MOC contents were higher than wetland soil. The proportions of the components of soil organic carbon in the three kinds of land use types are in accordance with the laws of organic carbon content. Correlation analysis showed that there was a significant correlation between HFOC, LFOC, CPOC, MOC and SOC in the three organic carbon fractions and could be used to indicate the dynamic change of SOC. These results indicate that the mangrove wetlands have a significant loss of soil SOC after being reclaimed, but reasonable cultivation management will make the crop soils have a greater carbon sequestration potential.