Abstract Regulation of water flow by dams for flood control and power generation has changed the patterns of water level fluctuation in the lower Yangtze River. By investigating the branch and leaf traits of M. laxiflora plants at various growth recovery stages along the water fluctuation gradient, this study uncovered the spatiotemporal response in the relationships among branch and leaf traits during growth to the regulated water level fluctuations. Results indicated leaf number (LN) and leaf-and-branch volume (LV) rapidly increased during the first 30 d of growth recovery. Afterwards, the increase in LN gradually slowed, while LV continued to increase steadily and was isometric to the increase in leaf-and-branch dry mass (LM). The investment strategy of this plant species changed from ‘fast return’ to ‘slow return’ as plant growth was restored. In the upper hydro-fluctuation zone, the LN vs. LM and leaf-and-branch water content (LWC) vs. LM comparisons exhibited negative allometric growth, while the LV vs. LM comparison exhibited positive allometric growth. In the middle hydro-fluctuation zone, the LN vs. LM and LV vs. LM comparisons exhibited isometric growth patterns, while the LWC vs. LM comparison exhibited positive allometric growth. In the lower hydro-fluctuation zone, the LN vs. LM comparison exhibited positive allometric growth, while the LWC vs. LM comparison exhibited negative allometric growth. As water level decreased, the investment strategies of the plants switched from prioritizing LV and LWC to LN, and shifted from ‘slow return’ to ‘fast return’. The above results indicate that changes in water level fluctuation patterns have greatly affected branch and leaf growth, as well as the growth relationships among branch and leaf traits in the remnant populations of M. laxiflora. Growth of these remnant populations, especially those at the lower hydro-fluctuation zone, was seriously affected and exhibited signs of degradation as a result. HIGHLIGHTS Regulation of water flow by dams for flood control and power generation has changed the patterns of water level fluctuation in the lower Yangtze River. The human water flow regulation impacts the allometric growth of M. laxiflora in terms of branch and leaf traits, as well as the investment strategies during growth. Clear differences were observed in the growth patterns of branches and leaves at different levels along the water fluctuation gradient.

中文翻译：

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枝叶生长关系对人体水流调控的时空响应：以杨梅残余种群为例

摘要 大坝防洪发电改变了长江下游水位波动格局。本研究通过沿着水分波动梯度调查不同生长恢复阶段的紫花植物枝叶性状，揭示了生长过程中枝叶性状对调节水位波动关系的时空响应。结果表明，在生长恢复的前 30 天，叶数 (LN) 和叶枝体积 (LV) 迅速增加。此后，LN 的增加逐渐减慢，而 LV 继续稳定增加，与叶和枝干干质量 (LM) 的增加等量。随着植物生长恢复，该植物品种的投资策略由“快回报”转变为“慢回报”。在上部水波动区，LN 与 LM 以及叶和枝条含水量 (LWC) 与 LM 的比较显示出负异速生长，而 LV 与 LM 的比较显示出正异速生长。在中间水波动区，LN 与 LM 和 LV 与 LM 的比较显示等长生长模式，而 LWC 与 LM 的比较显示正异速生长。在较低的水波动区，LN 与 LM 比较显示出正异速生长，而 LWC 与 LM 比较显示出负异速生长。随着水位下降，工厂的投资策略从优先考虑LV和LWC转向LN，从“慢回报”转向“快回报”。以上结果表明，水位波动规律的变化对枝叶生长影响较大，以及 M. laxiflora 残余种群中枝叶性状之间的生长关系。这些残余种群的生长，特别是在水文波动带下游的种群，受到严重影响，并因此出现退化迹象。亮点 大坝防洪发电改变了长江下游水位波动格局。人类的水流调节影响M. laxiflora的异速生长在枝叶性状以及生长过程中的投资策略。沿水分波动梯度不同层次的枝叶生长规律存在明显差异。这些残余种群的生长，特别是在水文波动带下游的种群，受到严重影响，并因此出现退化迹象。亮点 大坝防洪发电改变了长江下游水位波动格局。人类的水流调节影响M. laxiflora的异速生长在枝叶性状以及生长过程中的投资策略。沿水分波动梯度不同层次的枝叶生长规律存在明显差异。这些残余种群的生长，特别是在水文波动带下游的种群，受到严重影响，并因此出现退化迹象。亮点 大坝防洪发电改变了长江下游水位波动格局。人类的水流调节影响M. laxiflora的异速生长在枝叶性状以及生长过程中的投资策略。沿水分波动梯度不同层次的枝叶生长规律存在明显差异。亮点 大坝防洪发电改变了长江下游水位波动格局。人类的水流调节影响 M. laxiflora 的异速生长在枝叶性状以及生长过程中的投资策略。沿水分波动梯度不同层次的枝叶生长规律存在明显差异。亮点 大坝防洪发电改变了长江下游水位波动格局。人类的水流调节影响M. laxiflora的异速生长在枝叶性状以及生长过程中的投资策略。沿水分波动梯度不同层次的枝叶生长规律存在明显差异。