鄱阳湖典型湿地沉水植物的分布格局及其水环境影响因子

沉水植物是湖泊湿地生态系统中关键组分,调查研究沉水植物分布格局及其水环境影响因子,对于沉水植被的恢复与重建具有重要的指导意义。2013年5月初期分别对鄱阳湖典型湿地区域中有沉水植物的25个样地进行群落结构调查,采用系统取样方法对沉水植物进行调查采样并监测水环境因子,在野外调查的基础上运用GIS软件制作鄱阳湖典型区域沉水植物的生物量分布图,并采用主成分分析(PCA)和典范对应分析(CCA)方法分析其主要影响因子。结果表明:鄱阳湖湿地沉水植物以苦草(Vallisneria natans)为广布种,其中蚌湖及白沙湖以黑藻(Hydrilla verticillata)为优势种,白沙洲及乐安河龙口段以苦草为优势种,伴生种主要有金鱼藻(Ceratophyllum demersum)、马来眼子菜(Potamogeton malaianus)、菹草(P.crispus)、小茨藻(Najas minor)、大茨藻(N.marina)、刺苦草(V.spinulosa)和水车前(Ottelia alismoides)等。采用双向指示种分析法将研究区沉水植物分为6个群落;5月初大部分沉水植物尚处于生长季初期,生物量相对较低,仅菹草的生物量较大;沉水植物与浮叶植物共存现象明显。主成分分析(PCA)结果显示,第一主成分中水深、总磷和溶解氧等因子的系数值较大,第二主成分中pH值、化学需氧量和水体透明度等因子的系数值较大,是影响沉水植物分布的关键因子;典范对应分析(CCA)结果显示,水深、总磷和总氮对苦草和黑藻的影响显著,水体透明度是马来眼子菜的主要影响因子。

DISTRIBUTION PATTERN OF SUBMERGED PLANTS IN TYPICAL WETLANDS OF POYANG LAKE AND ITS INFLUENCING FACTORS OF WATER ENVIRONMENT

Submerged macrophytes are the key component of lake ecosystems. Studying the distribution of submerged macrophytes and the influencing factors of water environment is of significance for the establishment of vegetation restoration strategies. Field surveys for submerged macrophytes were carried out at 25 different sites in typical wetlands of Poyang Lake in May, 2013. Systematic sampling was conducted within the field sites and the water environment factors concentration values were determined in the laboratory. The biomass distribution map of the submerge plants were derived based on the field investigation data by using GIS methods, and the main influencing factors were analyzed by using Principal Component Analysis(PCA)and Canonical Correspondence Analysis (CCA). The results indicated that Vallisneria natans is one of the main submerged plants and the widespread species in the wetland of Poyang Lake. Hydrilla verticillata is the dominant species in Banghu Lake and Baishahu Lake, and V.natans is also the dominant species in Baishazhou Lake and Longkou Wetland. The major associated species included Ceratophyllum demersum, Potamogeton malaianus, P.crispus, Najas minor, N.marina, V.spinulosa, and Ottelia alismoides. The submerged plant communities in the study areas were divided into six classes by Two-way indicator species sorting methods. Most submerged macrophytes were still in the initial stage of growth and the biomass was still relatively low in the early of May, only the biomass of P.crispus was relatively high. The phenomenon of submerged and floating-leaved plants coexisting in the study areas was obvious. The results from PCA showed that the large coefficients of the first principal components included water depth, total phosphorus, and dissolved oxygen, while the large coefficients of the second principal components included pH value, chemical oxygen demand, and water transparency, which were the key factors affected the distribution of submerged plants. The results from CCA showed that the effects of water depth, total phosphorus and total nitrogen on V.natans and H.verticillata were obvious, and water transparency was the main factor which affected P.malaianus.