盐城大丰麋鹿自然保护区滨海湿地土壤有机碳分布特征

Distribution characteristics of soil organic carbon in the coastal wetland of Dafeng milu national nature reserve,Yancheng

在盐城大丰麋鹿自然保护区选取光滩、碱蓬、互花米草、白茅、獐毛、狗牙根和芦苇7种典型滨海湿地植物作为研究对象,分析不同植被群落土壤有机碳含量在垂直方向和季节上的分布特征,并估算湿地碳储量。结果表明:在水平方向上,土壤有机碳含量整体表现为互花米草>光滩>碱蓬>狗牙根>獐毛>芦苇>白茅;在垂直方向上,不同湿地类型土壤有机碳含量的分布均呈现非单调趋势,在0~40 cm土壤中,所有植被群落SOC含量的垂直分布规律大致相同,即随土壤深度增加SOC含量下降;在季节变化上,研究区不同植被群落SOC含量总体表现为10月>8月>4月>1月;土壤有机碳含量与土壤总氮、含水率、电导率、C/N呈显著的正相关,与土壤容重、pH呈显著的负相关。研究区土壤有机碳储量在0.65~7.32 kg·m^(-2)范围内,有机碳密度随土壤深度的增加呈现出近似“V”形分布,最高值出现在80~100 cm土层,最低值出现在20~40 cm土层。植被对滨海湿地土壤有机碳的含量和分布有着重要影响。互花米草的入侵明显增加了潮滩有机碳的积累,其演替过程也对湿地生态系统碳循环及碳的空间分布产生了重要影响。

Seven typical coastal wetland plant types such as bare land,Suaeda salsa,Spartina alterniflora,Imperata cylindrica,Aeluropus sinensis,Cynodon dactylon and Phragmites australis were selected to analyze the contents of soil organic carbon(SOC) and their carbon storage with seasonal and vertical variations in Dafeng Milu National Nature Reserve(DMNNR),Yancheng.The results showed that the S.alterniflora ranked first in SOC content,followed by the bare land,S.salsa,C.dactylon,A.sinensis,P.australis and I.cylindrica.Depth-dependent distribution of SOC content of different wetland types showed a non-monotonic trend.In 0~40 cm soil,the vertical distribution of SOC content in all vegetation communities were basically the same,which showed that SOC content decreased with the increase of soil depth.Seasonally,the SOC contents in DMNNR were in an order of October > August > April> January.Correlation analysis indicated that soil total nitrogen,moisture content,electrical conductivity and C/N were positively correlated with SOC content;soil bulk density and pH were negatively correlated with SOC.The SOC storage in DMNNR was in the range of 0.65~7.32 kg·m^(-2).The SOC density showed an approximate "V" distribution with the increase of soil depth,with the highest value in 80~100 cm soil layer and the lowest value in the 20~40 cm soil layer.Vegetation has an important impact on the content and distribution of SOC in coastal wetland.The invasion of S.alterniflora significantly increased the accumulation of organic carbon in tidal flat,and its succession process also had an important impact on the carbon cycle and spatial distribution of wetland ecosystem.