互花米草入侵对黄河口盐沼湿地土壤溶解性有机碳空间分布的影响

Impact of Spartina alterniflorainvasion on spatial distribution of dissolved organic carbon in salt marsh soils of the Yellow River Estuary,China

互花米草是我国滨海盐沼湿地中广泛分布的入侵植物,可对盐沼土壤的元素循环产生深远影响.本研究以黄河三角洲典型互花米草分布区为研究对象,沿垂直于潮沟方向选择连续带状互花米草区(CR)、斑块状互花米草区(P)、斑块间裸滩(BL)以及互花米草与盐地碱蓬交错区(MZ)样地,分别分层采集土壤剖面样品,探讨互花米草入侵对土壤溶解性有机碳(DOC)质量分数w的空间分布特征的影响.研究结果表明:研究区表层(0~20cm)及深层(>20~100cm)土壤w(DOC)的变化范围分别为5.68~112.17mg·kg^(-1)与4.27~94.28mg·kg^(-1);互花米草入侵显著增加了表层土壤w(DOC)(P<0.05),土壤w(DOC)沿互花米草扩散方向逐渐降低.除斑块状互花米草区外,土壤w(DOC)随着土壤深度增加逐渐降低.Spearman相关性分析结果表明,表层土壤w(DOC)与土壤有机碳即w(SOC)(P<0.05)以及w(黏粒)(P<0.01)呈显著正相关关系,而与pH呈负相关关系(P<0.01).多元分析表明表层土壤与深层土壤的DOC与土壤理化因子之间呈现不同的作用关系,说明互花米草入侵改变了滨海盐沼土壤DOC的空间分布特征,本文研究结果为深入开展滨海盐沼湿地碳循环研究提供基础.

Spartina alterniflora,the most widely distributed alien species in coastal wetlands in China,can have profound effects on elemental cycles in coastal salt marshes.A sampling belt was selected in a typical distribution zone of Spartina alterniflora in the Yellow River Estuary,which was perpendicular to a tidal creek,including continuous ribbon zone,patch zone of Spartina alterniflora,bare land and a mixed zone of Spartina alterniflora and Suaeda salas.Soil samples were collected from soil profiles in triplicates at different intervals in each of the selected four sampling zones.Soil DOC and physi-chemical properties were then measured to investigate the impact of Spartina alterniflora invasion on spatial distribution of DOC.Our results showed that DOC contents in upper（0-20cm）and deeper soils（20-100cm）ranged from 5.68to112.17mg·kg^-1 and from 4.27 to 94.28mg·kg^-1,respectively.Spartina alterniflorainvasion significantly increased DOC contents in upper soils（P〈0.05）,and a decreasing trend of DOC level was observed along the sampling belt.With the exception of patch zone,DOC contents all decreased gradually in other zones with depth along soil profiles.Spearman correlation analysis indicated a strong positive correlation between DOC and soil organic carbon（P〈0.05）and clay content（P〈0.01）,while DOC was significantly negatively correlated with pH（P〈0.01）.Multivariate analysis showed different relationships between DOC and soil physicalchemical properties in upper and deeper soils.Therefore,spatial distribution of soil DOC can be altered after Spartina alterniflorainvasion This work provides some basic knowledge about carbon cycles in coastal salt marshes.