基于Ecopath模型的北方典型中小河流生态系统营养结构与能量流动分析

    Analysis on the Ecosystem Trophic Structure and Energy Flow of Typical Small and Medium Rivers in Northern China on Ecopath Model

    • 摘要: 中小河流多而广,是与人类最为亲近的河流类型,但受到的人为改造及生产生活活动干扰强度也最大,表现出的生态退化程度更为明显。以北方典型中小河流清潩河(许昌段)为例,基于2021年夏、秋季水生态调查结果,采用Ecopath with Ecosim软件构建了夏、秋季食物网模型。模型模拟结果显示,清潩河生态系统主要由5个整合营养级(范围值为1.00~3.29)构成,其中,营养级Ⅰ、Ⅱ传递效率较低,严重阻碍了能量向更高营养级流动,夏、秋季系统总转化效率分别仅为1.08%和1.82%。清潩河生态系统夏、秋季交互营养关系无明显变化,捕食者中除翘嘴鲌外均表现出对饵料生物较强的抑制作用。对生态系统总体特征的分析发现,夏季生态系统规模(总流量为2 571.06 t·km-2)大于秋季(1 472.58 t·km-2),同时,Finn循环指数(FCI)和Finn平均路径长度(FML)计算结果也表明夏季生态系统成熟度和稳定性优于秋季。最后,利用食物网模型筛选出不同营养级范围的关键功能组为浮游植物、软体动物和翘嘴鲌。根据这3类生物的习性特征与生境适宜性需求,提出限制浮游植物优势种生长、加大对软体动物捕食压力和恢复翘嘴鲌种群等建议,为清潩河及同类河流生态修复提供方法支撑和决策参考。

       

      Abstract: There are a number of small and medium-sized rivers throughout China, which are the closest to humans. But they are also affected by man-made transformation and production and life activities and show more obvious ecological degradation. Taking the Xuchang section of the Qingyi River as the study area, a mass-balance food web model was established with "Ecopath with Ecosim" according to the data of aquatic organisms collected in the summer and autumn of 2021. The achieved results reveal that the Qingyi River ecosystem mainly consists of five integrated nutrient levels (1.00-3.29), and due to the low transfer efficiency of trophic levels I and II, the energy flow to the higher nutrient level was seriously hindered, and the conversion efficiency of the whole system was only 1.08% and 1.82%. The mixed trophic impacts did not alter in summer and autumn, and predators except Culter alburnus exhibited a strong inhibitory effect on the bait organisms. A comprehensive analysis of multiple indicators, including parameters close to maturity, resilience and stability of the system, indicate that the total flow rates of the Qingyi River ecosystem were 2 571.06 and 1 472.58 t·km-2 in summer and autumn, respectively, and the size of the ecosystem in summer is greater than that in autumn and Finn′s cycling index (FCI) and Finn′s mean path length (FML) also revealed that the ecosystem maturity and stability in summer were superior to those in autumn. Finally, according to the food web model, three key functional groups at various nutrient levels in the Qingyi River ecosystem have been selected as phytoplanktons, molluscs, and Culter albus, while maintaining the appropriate requirements of key functional habitats and growth habits, the pertinent suggestions for restoring the ecosystem, such as limiting the growth of dominant phytoplankton species, increasing mollusk predator pressure, and restoring the Culter alburnus population are presented. The findings of this study could provide decision-making basis and scientific support for the ecological restoration of the Qingyi River and similar rivers.

       

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