Su Xiaolei, Bejarano María Dolores, Jansson Roland, Pilotto Francesca, Sarneel Judith M, Lin Feng, Wang Yi, Cai Fu, Wu Shan, Zeng Bo
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing Key Laboratory of Plant Ecology and Resources in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China.
Department of Natural Systems and Resources, Universidad Politécnica de Madrid, Madrid, Spain.
Glob Chang Biol. 2025 Feb;31(2):e70042. doi: 10.1111/gcb.70042.
Over two-thirds of global rivers are subjected to flow regulation. Although it is widely recognized that flow regulation can adversely affect riparian vegetation-a critical component of river ecosystems-the specific roles of various drivers remain poorly understood. To address this gap, we conducted a broad-scale meta-analysis, aiming to elucidate how different factors mediate the adverse impacts of flow regulation on riparian vegetation. This meta-analysis encompassed 59 papers, spanning 278 dams constructed on 146 rivers. We extracted data on four key indices of riparian vegetation: species richness and abundance of all riparian species, and those indices exclusively for non-native species. Indices were compared between regulated and free-flowing or pre-damming rivers to quantify the impact of flow regulation. Our meta-analysis revealed a moderate but significant reduction in the richness and abundance of all riparian species under flow regulation, coupled with a strong increase in the abundance of non-native species. Riparian vegetation in arid and continental climate regions experienced stronger negative impacts than those in tropical and temperate climates. Furthermore, the adverse effects on riparian vegetation were more pronounced downstream of dams than upstream. Considering climate region, study identity, and relative position to the dam as random variables, it became evident that years since flow regulation emerged as the most important factor influencing species richness. Over time, richness gradually recovered from initially low levels. However, this recovery was slowed by increasing flow regulation intensity (percentage of annual runoff stored). Additionally, the impact was more evident in larger rivers. To support regulated river management, we recommend prioritizing the protection of riparian vegetation in arid and continental climates, with emphasis on areas downstream of dams, limiting flow regulation intensity, particularly in larger rivers, and monitoring non-native species to prevent disproportionate spread.
全球超过三分之二的河流受到流量调节的影响。尽管人们普遍认识到流量调节会对河岸植被产生不利影响——河岸植被是河流生态系统的关键组成部分，但各种驱动因素的具体作用仍知之甚少。为了填补这一空白，我们进行了一项大规模的荟萃分析，旨在阐明不同因素如何介导流量调节对河岸植被的不利影响。这项荟萃分析涵盖了59篇论文，涉及在146条河流上建造的278座水坝。我们提取了河岸植被四个关键指标的数据：所有河岸物种的物种丰富度和丰度，以及仅针对非本地物种的那些指标。将这些指标在受调节河流与自由流动或筑坝前的河流之间进行比较，以量化流量调节的影响。我们的荟萃分析表明，在流量调节下，所有河岸物种的丰富度和丰度有适度但显著的下降，同时非本地物种的丰度大幅增加。干旱和大陆性气候地区的河岸植被受到的负面影响比热带和温带气候地区更强。此外，对河岸植被的不利影响在水坝下游比上游更为明显。将气候区域、研究对象以及与水坝的相对位置视为随机变量，很明显，自流量调节开始以来的年份成为影响物种丰富度的最重要因素。随着时间的推移，丰富度从最初的低水平逐渐恢复。然而，这种恢复因流量调节强度（年径流量储存百分比）的增加而放缓。此外，这种影响在较大的河流中更为明显。为了支持受调节河流的管理，我们建议优先保护干旱和大陆性气候地区的河岸植被，重点是水坝下游地区，限制流量调节强度，特别是在较大的河流中，并监测非本地物种以防止其过度扩散。
