深圳湾不同生境湿地大型底栖动物次级生产力的比较研究

以深圳湾红树林为例,于2010年1—12月每月1次对红树林和3种对照生境(芦苇鱼塘,基围鱼塘和光滩)的大型底栖动物进行了采样调查,并对其次级生产力、P/B值(次级生产力与生物量的比值)、优势种和生物多样性进行了计算与分析。结果表明,不同生境大型底栖动物群落次级生产力和P/B值差异明显,芦苇鱼塘、基围鱼塘、光滩和红树林生境的次级生产力分别为:6.81、147.50、74.70和105.78 g.m-.2a-1;P/B值分别为:1.10、1.53、1.41和3.58 a-1。红树林生境的次级生产力较高,仅次于基围鱼塘,P/B值显著高于其他3种生境,周转速率最快。结合大型底栖动物优势种和生物多样性的季节变化分析表明,红树林生境大型底栖动物生物多样性最丰富,生态系统抵抗力和恢复力最高,生态系统最稳定。由此说明城市化地区红树林生境对大型底栖动物周转速率和物种多样性有明显促进作用,可以增加生态系统营养的保持力和生态系统的稳定性,对于缓解城市化对湿地生态系统造成的威胁具有重要作用。

A comparison study on the secondary production of macrobenthos in different wetland habitats in Shenzhen Bay

Secondary productivity is an important indicator of the variation of the structure, function and stability of an ecosystem. The goal of this study was to test the hypothesis mangrove habitat promotes the production of macrobenthos and increases ecosystem stability under the influence of urbanization. We collected samples monthly in four basic habitats, Phragmites communis reed beds with frequently inundated soil (reed beds), gei wai ponds, mudflats, and mangrove habitat, and analyzed the secondary productivity of macrobenthos, the production/biomass (P/B) ratio, and the dominance and the diversity of macrobenthos from January to December of 2010. The results show secondary productivity in these four habitats varied widely. The secondary productivity in reed beds, gei wai ponds, mudflats, and mangrove habitat was 6.81, 147.50, 74.70, and 105.78 g·m^-2 × a^-1, respectively; and the P/B ratios were 1.10, 1.53, 1.41, and 3.58 a^-1, respectively. Secondary productivity in the mangrove habitat was only lower than in the gei wai ponds, while mangroves had the highest P/B ratio, meaning the turnover rate was fastest. The seasonal variation of secondary productivity among the four habitats also varied; gei wai ponds had the highest secondary productivity and it remained relatively stable all year. The other three habitats had the same trend with secondary productivity high in spring and autumn, and lowest in summer. The seasonal variation of the P/B ratio in geiwai ponds and reed beds was relatively stable, while the mangrove and mudflat habitats had the same trend with higher P/B in spring and autumn, and lowest in summer. The species composition and dominance in the four habitats were significantly different seasonally. Reed beds were dominated by two gastropods, Cerithidea cingulata in spring and summer, and Melanoides tuberculata in winter. The gastropod Sermyla riqueti dominated gei wei ponds all year. The dominant species of mudflats were Nereis glandicincta in summer, S. riqueti in autumn, S. riqueti and Cipangopaludina chinensis in winter. Mangroves were dominated by Ellobium aurismidae in summer and autumn and Uca urvillei in winter. The macrobenthic diversity also varied seasonally in the four habitats. The level of biodiversity in the four habitats was mangrove > mudflats > gei wai ponds > reed beds, with mangroves having the highest diversity in all four seasons. The seasonal variation of macrobenthic diversity in gei wai ponds and reed beds was relatively stable, while the mangrove and mudflat habitats had the same trend with lowest biodiversity in summer and higher in autumn, that may be resulted by tropical storm. The increase of macrobenthic productivity, the P/B ratios and biodiversity in the autum than in the summer is bigest in mangrove habitat. Based on the analysis of the macrobenthic productivity, the P/B ratios, and the seasonal variation of the macrobenthic dominance and diversity, we concluded the mangrove habitat had the highest biodiversity, ecosystem resistance to change and resilience, and conclude the mangrove ecosystem was the most stable ecosystem. Above all, the mangrove habitats played a significant role in promoting species diversity for macrobenthos, improving the turnover rate, and in increasing both ecosystem nutrient retention and stability which reduced urbanization threats to the health of the ecosystem.