崇明东滩抛荒鱼塘的自然演替过程对水鸟群落的影响

人工湿地抛荒的现象普遍存在,但针对抛荒后的自然演替过程对水鸟群落影响的研究较少.于2007、2008、2011年对崇明东滩自然抛荒的人工鱼塘水鸟群落展开调查,探究抛荒后的自然演替过程对水鸟群落结构及不同水鸟类群的影响.3a累计观察到水鸟59种12819只,隶属6目12科.其中抛荒前最多,共53种11001只;抛荒第1年22种1673只;抛荒第4年最少,9种145只.鱼塘抛荒后水鸟种类和数量下降剧烈,物种多样性先上升再下降,均匀度逐年上升,优势度先下降再上升.方差分析结果表明,5个群落特征都存在极显著年度差异(P1＜0.01;P2＜0.01;P3＜0.01;P4=0.003;P5＜0.01).非参数检验结果表明,不同类群水鸟的种类和数量逐年下降趋势明显,且年际差异极显著.即抛荒后的自然演替过程对水鸟群落产生了不利影响.建议采取人工管理措施防止旱化,增加环境异质性,恢复水鸟群落多样性.

The impact of natural succession process on waterbird community in a abandoned fishpond at Chongming Dongtan, China

In recently years, the artificial wetlands such as fishponds and rice pads have become the main habitats type for waterbird due to the decrease of natural wetland. Such phenomenon exists generally in Yangtze River coastline since the coast wetlands were reclaimed during last decade. However, part of artificial wetlands in these areas is being abandoned by local farmers in the reasons of labour cost increasing and aquatic product price decreasing comparatively. Some studies concluded that the abandonment of fishpond caused the deterioration of soil and water quality, and the decrease of benthic animals. However there are few studies about the influence of natural succession after the abandonment on waterbird community. Chongming Dongtan National Nature Reserve is one of the international wetland (Ramsar Site) for waterbird conservation, where we selected the abandoned fishpond as our research area to undertake the waterbird studies in 2007, 2008 and 2011, aiming to the impact of rapid succession after abandonment on waterbird community structure, and raising relative recommendations on the further management of these abandoned fish ponds for local government.In a total of 12819 waterbirds of 59 species were observed in the three years, which belonged to 6 Orders and 12 Families. Among the total, in the year of 2007, pre-abandonment period, we counted 11001 waterbirds of 53 species, with the most abundance and richness value in our study years; in the year of 2008, the first year of fishponds abandoned period, we counted 1673 waterbirds of 22 species; in the year of 2011, the fourth year of fish ponds abandoned period, we only counted 145 waterbirds of 9 species; which indicated the waterbirds abundance and richness dropped dramatically after the fishpond was abandoned. The study results of variance analysis showed that the richness, abundance, species diversity, evenness and dominance of waterbird community all had highly significant differences among years (P₁<0.01; P₂<0.01; P₃<0.01; P₄=0.003; P₅<0.01). The result of non-parametric test described that, the richness and abundance of different waterbird groups had highly significant differences among years. The findings of this study suggested that waterbird abundance and richness had the dropping trend, meanwhile water level and the percentage of water area decreased and vegetation coverage increased; the species diversity increased as well as the percentage of mudflat; the evenness had the same increasing trend as vegetation coverage, but opposite trend presented in the water level and the percentage of water area. The results also indicated that different waterbird groups such as waterfowls and shorebirds reacted variously to the different environment factors, for instance, the abundance and richness of shorebirds have risen rapidly in the first year of fish pond abandoned while the other groups decreased obviously.In order to raise the conservation value of these fishponds abandoned in this Ramsar Site, we recommend undertaking proper management measures in these areas to prevent the drought as well as increasing the heterogeneity of habitat for the waterbird conservation.