As one of the most important interfaces of material cycle, energy and species flows between coastal wetlands and adjacent waters; mangrove forest edge is of great scientific importance in understanding the interaction between different ecosystems, biogeomorphogical processes and dynamics of soil organic carbon pool in coastal areas. In order to determine the edge effects and their impact on the soil organic carbon pool, 4 coastal landform types of mangrove distribution area in the east coast of Leizhou Peninsula were selected for investigation. Three subzones of barren flat, forest edge and forest interior were then further indentified in each landform type. The forest structure in the edge and interior, as well as the e-daphic physiochemical features for all three subzones were investigated in low tide in August, 2011. Different patterns of vegetation and soil physiochemical indicators were compared among the 4 mangrove land-forms. Generally, the edge effect on vegetation was characterized by relatively lower canopy height, leaf area index and species richness in the forest edge than the interior (except the estuarial mangroves). Vegetation coverage decreased with landforms in the forest edge as estuary(QL)> inner bay(TF)> island(TC) > wave hit bench(TJ), coinciding with the degree of wave and storm hit to the areas. The edge effect on soil physicochemical properties in most cases (except TF, the inner bay) showed soil pH, mean grain size in the forest edge were less than that in the barren flat, while redox potential, salinity showed higher on the contrary. But these soil properties in the forest interiors were largely variable among different land-forms, since they could be sensitive to the effects of vegetation succession behind the forest edge and mic-rotopography as well. However the SOC (surface soil organic carbon content) and soil organic carbon density increased significantly from the barren flat to the interior in each type of the landforms. Principal component analysis and correlation analysis showed the first principal component, reflecting the joint effect of vegetation cover, leaf area index and soil pH, was negatively correlated with the surface organic carbon density. In other word, despite the variation and strong impact of hydrogeomorphology, organic carbon enrichment in mangrove soil was resulted from the increase of primary production and development of acid edaphic settings.%作为滨海湿地与邻近海区之间物质循环、能量和物种流动及其相互作用的重要界面,红树林的边缘效应对研究海陆生态系统相互作用,滨海湿地生物地貌形成过程以及海岸带有机碳库分布格局等方面的具有重要意义.文章以雷州半岛东岸红树林4种典型地貌分布区为重点,通过调查红树林前缘光滩,林缘及林内植被及土壤理化特征的变化,探讨红树林边缘效应的表现及其对土壤有机碳库的影响.结果表明,不同地貌类型红树林边界区的群落结构及土壤理化因子分布特征有所不同.边界区群落特征表现为林缘的冠层低于林内,叶面积指数低于林内,物种丰富度林内高于林缘(除河口区外),且林缘的植被盖度受风浪影响显著,表现出河口区＞内湾区＞岛屿区＞前沿浪击区.土壤理化性质边缘效应表现为林缘的pH值、粒度低于光滩,氧化还原电位、盐度高于光滩(除内湾区外),而林内的土壤理化性质波动较大,可能受林缘植被演替及地貌双重影响.不同地貌单元红树林边界区的土壤表层有机碳含量,有机碳密度均表现为林内＞林缘＞光滩.综合影响表层土壤有机碳的主要生物及非生物因子进行主成分分析和相关分析,结果显示土壤表层有机碳密度与环境第一主成分呈显著负相关,即受植被盖度,叶面积指数和土壤pH因子影响密切.红树林土壤有机碳沉积虽然受到不同水文地貌的影响,但总体而言,红树林初级生产输入和土壤酸性环境对红树林林下土壤有机碳库的富存贡献显著.
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