河口湿地景观格局与大型底栖生物群落的尺度效应研究

Landscape pattern of estuarine wetland and its multi-scale effects on macrobenthos diversity

通过高空间分辨率遥感手段,获取长江河口潮滩的景观特征,选取了57个样点进行底栖动物采样调查及指数计算,分别在4个不同空间尺度对生境景观指数与大型底栖动物群落分布的关系进行量化分析。通过了解景观格局在不同尺度下的变化规律,以及进行Spearman相关分析、冗余分析,筛选得到长江河口潮滩大型底栖动物群落结构研究的最优空间尺度,并且得到该尺度下与底栖动物物种丰富度和多样性显著相关的景观指数。结果显示:半径为75 m空间尺度的景观特征对底栖动物物种丰富度和多样性的解释度最好,可以作为后续研究的最优空间尺度。在此尺度下,底栖生物群落多样性与丰富度与景观的破碎化程度、湿润地表斑块(水洼、临海光滩、潮沟)的散布度、土壤碳储量低下的斑块(光滩)的连通度呈显著负相关;与植被斑块(芦苇、糙叶苔草、海三棱藨草、互花米草)的连通度、潮沟的连通度呈显著正相关。这些对后续正确理解河口生境异质性及其结构变化有重要意义,有助于在合理的尺度范围内分析河口湿地大型底栖动物多样性或生态过程的影响机制,对今后在底栖动物栖息地利用效率、栖息地分类、栖息地屏障和通道功能的研究有实际意义。

In this study,the landscape characteristics of the tidal flats of the Yangtze River Estuary were obtained by means of high spatial resolution remote sensing.57sampling points were selected for index calculation of macrobenthos.The landscape indices and macrobenthos distribution were calculated on four different spatial scales.By understanding the changing pattern of landscape at different scales and through Spearman correlation and redundancy analysis,the optimal spatial scale for studying the community structure of the macrobenthos in the tidal flat of the Yangtze River Estuary was screened out as a radius of75m,which had the best interpretation for species richness and diversity of macrobenthos.At the same time,the optimal group of landscape indices was obtained,which was significantly related to the species richness and macrobenthos diversity.The results showed that landscape features within the75m radius spatial scale had the best interpretation of macrobenthos species richness and diversity,and can be used as the optimal spatial scale for the follow-up studies.At this scale,the diversity and abundance of macrobenthic communities were significantly negatively correlated with the degree of fragmentation of the landscape,the degree of dispersion of the wet surface patches(water pit,seashore salt marsh,tidal channel),and the connectivity of the patches with low productivity(salt marsh).On the contrary,the diversity and abundance of macrobenthic communities were significantly positively correlated with the connectivity of the dominant vegetation patches(Phragmites australis,Carex scabrifolia,Scirpus mariqueter,Spartina alterniflora)and the connectivity of tidal channels.These are important for the subsequent researches by correct understanding of habitat heterogeneity and structural changes in the estuary.It helps to analyze the mechanisms of macrobenthos diversity or ecological processes in the estuarine wetland at a reasonable scale.It has the practical significance for the researchers to study the macrobenthic habitat use efficiency,habitat classification,the barrier and channel functions of habitat in the future.