摘要:立柳因良好的耐淹性常被用于三峡库区消落带的植被重建。为探讨立柳如何通过营养元素的积累和分配来适应库区消落带冬季水淹，于2015年5月对三峡库区消落带植被修复示范基地内3个采样带（175 m，170 m和165 m）中立柳的生长状况以及叶、枝条和根的营养元素含量特征进行分析。结果表明：（1）经过3个水淹周期后，随着水淹强度的增加，立柳的株高、基径和冠幅均受到一定的抑制；但与种植初期相比，3个采样带中立柳的株高、基径和冠幅均显著增加，且生长状态良好。（2）立柳各器官中营养元素含量均处于正常水平，但水淹抑制了根中N、P的积累，促进了Fe和Mn的积累；水淹显著降低了海拔165 m处立柳叶和枝条中Ca含量、枝条和根中Cu和Zn的含量。（3）水淹胁迫导致N、P、K、Mg元素更多地在叶中积累，而Cu和Zn在枝条中大量积累，这有利于退水后植株的光合合成以及恢复生长；Fe、Mn元素在根中大量积累，其对根系正常生理可能造成的干扰值得进一步关注。研究表明，在不同的水淹胁迫梯度下，立柳可针对性地调整其营养元素积累和分配方式，保持植株正常的生长状态，对维护三峡库区消落带生态系统的正常结构和功能具有重要作用。但在库区消落带植被恢复和重建工作中，需加强170 m以下海拔区域立柳生长的监测和研究。



Abstract:After the completion of the Three Gorges Dam, a hydro-fluctuation belt with a range of 30 m and an area of about 350 km² was formed. The unique anthropogenic hydrological regime of the Three Gorges Dam has had significant negative impacts on the reservoir's ecosystem. A large number of native flooding-intolerant plants living within the belt have gradually died due to off-season flooding, which negatively affected the ecosystem structure and function of the hydro-fluctuation belt. Therefore, vegetation reconstruction and restoration in the Three Gorges Reservoir (TGR) is urgent; previous studies have shown that Salix matsudana has been used for vegetation reconstruction due to its flood resistance abilities. The nutritional accumulation and distribution of plants in a certain degree can reflect eco-physiological processes, and can serve as a crucial indicator of the structure and function of the local ecosystem. In order to explore how S. matsudana adapts to the winter flooding in the hydro-fluctuation belt of the TGR through the accumulation and distribution of nutrients, the growth status and the nutrient content in leaves, branches, and roots of S. matsudana in three sampling belts (at altitudes of 175 m, 170 m, and 165 m) of the vegetation remediation demonstration base of the TGR were measured in May 2015. The results showed that:(1) After three flooding cycles, the plant height, base diameter, and crown width of S. matsudana were inhibited by the increase of flooding intensity; however, compared with the initial stage of planting, the plant height, base diameter and crown width of S. matsudana in the three sampling belts were significantly higher, and the growth status was good as well. (2) The nutrient content in all organs of S. matsudana were maintained at normal levels, but flooding reduced the content of N and P in roots and increased the Fe and Mn content. In addition, winter flooding resulted in a significant decrease in the content of Ca in S. matsudana leaves and branches and the content of Cu and Zn in the branches and roots at an altitude of 165 m. (3) Under flooding stress, N, P, K, and Mg elements accumulated more in the leaves, while Cu and Zn accumulated in the branches, which is beneficial for photosynthetic rates and recovering growth of plants after water withdrawal. While winter flooding leads to higher accumulation of Fe and Mn elements in the roots, this disturbance to normal root physiology deserves further attention. Studies have shown that under different flood stress conditions, S. matsudana can adjust the accumulation and distribution of nutrients in a targeted manner to ensure a normal growth state. However, in this study of vegetation restoration and reconstruction in the water-fluctuating zone of the reservoir, we found that it is necessary to strengthen the monitoring and research of sustainable growth of S. matsudana at altitudes below 170 m.





PDF全文下载地址:

https://www.ecologica.cn/stxb/article/pdf/stxb201811162485