不同植被类型对淤泥质潮滩有机碳来源和储量的影响——以茅埏岛为例

Effects of different vegetation types on the source and storage of organic carbon in muddy tidal flats:Taking Maoyan Island as an example

滨海湿地具有较强的碳汇能力,不同植被类型会对沉积物中有机碳的来源和储量产生重要影响。在茅埏岛无植被、老红树林、幼红树林和互花米草等4种淤泥质潮滩各采集1根沉积物柱状样品(柱样长度均为1 m,按10 cm间隔分样),测定沉积物粒度、总有机碳(TOC)、总氮(TN)等参数,分析和讨论沉积物有机碳来源、储量及其影响因素。结果显示:1)无植被潮滩、老红树林潮滩、幼红树林潮滩和互花米草潮滩沉积物中TOC平均含量依次为0.71%±0.03%,0.76%±0.16%,0.69%±0.12%,0.83%±0.09%。在0~20 cm层,有植被潮滩TOC含量显著高于无植被潮滩;在20~100 cm层,互花米草潮滩沉积物TOC含量高于其它潮滩类型。2)茅埏岛潮滩中互花米草潮滩沉积物有机碳储量最高,达5.79 kg m^(2),其次是老红树林潮滩(5.61 kg m^(2)),幼红树林潮滩(4.95 kg m^(2))和无植被潮滩(4.84 kg m^(2))有机碳储量较低。互花米草潮滩和红树林的覆盖均在一定程度上增强了潮滩的储碳能力。3)互花米草潮滩沉积物中的有机碳主要以陆源为主,占比57.75%;本地植物贡献在老红树林潮滩沉积物中占比最大,占比32.65%;幼红树林潮滩和无植被潮滩沉积物中有机碳均以海源贡献为主,分别占比61.47%和50.45%。

Coastal wetlands are known for their significant capacity as carbon sinks,with different types of vegetation playing a crucial role in both sourcing and storing organic carbon in sediments.In this study,sediment core samples(1-meter length,sampled at 10 cm intervals)were collected from four different tidal flats on Maoyan Island,including bare mudflat,mature mangrove,young mangrove,and Spartina alterniflora wetland.The particle size,total organic carbon(TOC),total nitrogen(TN)and other parameters of each layer of sediment were measured at 10 cm interval.The source,storage and influencing factors of sediment organic carbon were analyzed and discussed.The results showed that:(1)The average TOC content in sediments from bare mudflat,mature mangrove,young mangrove,and Spartina alterniflora wetland were 0.71%±0.03%,0.76%±0.16%,0.69%±0.12%,and 0.83%±0.09%,respectively.Vegetated flats had significantly higher TOC content than that in bare mudflat in the 0-20 cm layer,while Spartina alterniflora wetland had higher TOC content than those in other tidal flat types in the 20-100 cm layer.(2)Among the 1 m of sediment from Maoyan Island tidal flats,the carbon storage in the Spartina alterniflora wetland was the highest,reaching 5.79 kg m^(2),followed by the mature mangrove forest(5.61 kg m^(2)),the young mangrove forest(4.95 kg m^(2)),and the bare mudflat(4.84 kg m^(2))with relatively lower organic carbon storage.The coverage of Spartina alterniflora and mangroves enhanced the carbon storage capacity of tidal flat to a certain extent.(3)The organic carbon in the tidal flat sediments of Spartina alterniflora was mainly from terrigenous sources,accounting for 57.75%;the contribution of native plants accounted for the largest proportion in the mature mangrove sediments,accounting for 32.65%;the organic carbon in the sediments of young mangroves and bare mudflat was dominated by marine sources,accounting for 61.47%and 50.45%,respectively.