江苏中部潮滩湿地土壤有机碳分布特征及影响因子

Distribution characteristics and influencing factors of soil organic carbon in tidal flat wetland of central Jiangsu,China

以江苏省盐城市川东河口南侧潮滩湿地为研究对象,选取互花米草盐沼和无植被光滩两种典型滨海湿地,分别在冬夏季测定土壤有机碳(SOC)含量,探究湿地土壤有机碳的时空分布规律及其影响因素。结果表明:土壤有机碳含量在光滩区域为0.75~2.38 g·kg^(-1),互花米草盐沼区域为2.07~18.59 g·kg^(-1),且呈现海向递减趋势,互花米草盐沼区域约为光滩区域的2.5~3.5倍;垂向分布上,1 m深度范围内,光滩区域有机碳含量无明显变化,而互花米草盐沼区域呈现先增大后减小的变化规律,峰值在20~30 cm深度范围内;土壤有机碳含量具有显著的季节性差异,表现为夏季高于冬季,互花米草盐沼区域夏季较冬季高5%~10%,光滩区域夏季较冬季高43%。互花米草盐沼区域土壤有机碳含量与土壤含水率、盐度呈显著正相关,与泥沙粒径呈显著负相关;光滩区域土壤有机碳含量与土壤理化因子无明显相关性。表明滨海湿地多种土壤理化因子与SOC的相关性建立在有植被覆盖的基础之上。研究结果可为我国滨海湿地蓝碳生态系统的保护提供参考。

We measured winter and summer soil organic carbon(SOC)contents in two typical coastal wetlands,the Spartina alterniflora salt marsh and the non-vegetation mudflat,on the south side of the Chuandong River Estuary in Yancheng,Jiangsu Province.We investigated the spatiotemporal variations of soil organic carbon contents and its driving factors.The results showed that SOC content ranged from 0.75 to 2.38 g·kg^(-1)in the mudflat area and from 2.07 to 18.59 g·kg^(-1)in the S.alterniflora salt marsh area,showing a decreasing trend towards the sea.The SOC content in the S.alterniflora salt marsh area was approximately 2.5 to 3.5 times of that in the mudflat area.Within a depth range of 1 m,there was no vertical variation in SOC content in the mudflat area,but an increasing and then decreasing pattern in the S.alterniflora marsh area with the peak occurring in the depth range of 20 to 30 cm.Soil organic carbon content exhibited significant seasonal difference,with higher value in summer than in winter.The summer SOC content was 5%to 10%higher than that in winter in the S.alterniflora marsh area,while it was 43%higher in summer than in winter in the mudflat area.In the S.alterniflora marsh area,soil organic carbon content was positively correlated with soil moisture and salinity,but negatively correlated with sediment particle size.In contrast,there was no significant correlation between soil organic carbon content and soil physicochemi-cal factors in the mudflat area.Those results indicated that the correlation between various soil physicochemical factors and SOC is established on the basis of vegetation cover in coastal wetlands.Our findings could provide valuable insights for the conservation of blue carbon ecosystems in coastal wetlands in China.