Following a review of the European distribution, habitat requirements and life history characteristics of two riparian tree species, Alnus incana (L.) Moench (grey alder, a member of the Betulaceae family) and Populus nigra L. (black poplar, a member of the Salicaceae family), we explore their changing spatial distribution and topographic position within a 7 km, island braided reach of the Tagliamento River, Italy, where Populus nigra dominates the woody vegetation cover. Combining field observations and information extracted from aerial images, airborne lidar data and river flow time series for the period 1986–2017, we investigate (a) the changing spatial distribution of all (P. nigra‐dominated) woody vegetation and of A. incana alone; (b) whether river bed topography can be associated with these changing spatial distributions and (c) we consider whether A. incana displays any particular characteristics in its spatial and topographic distribution that may indicate that it is complementing the physical engineering role of P. nigra. We show that A. incana predominantly grows in lines along channel, island and floodplain edges, bordering wooded areas dominated by P. nigra and that areas supporting A. incana are associated with the topographic development of the river bed. We conclude that A. incana appears to be acting as a complementary physical engineer to P. nigra, suggesting that similar complementary physical engineering of river beds may be achieved by species with different life history traits to influence landform development in other river environments.

中文翻译：

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由两种河岸树种对辫状河流的物理工程：来自航空影像和机载激光雷达的证据

在回顾了两种河岸树木的欧洲分布，生境要求和生活史特征后，Alnus incana（L.）Moench（灰al木，Betulaceae的成员）和Populus nigra L.（黑杨，Betulaceae的成员）柳科），我们探索了它们在意大利塔利亚门托河7公里长的岛辫状河段中不断变化的空间分布和地形位置，其中黑杨在木本植物植被中占主导地位。组合来自航空图像，机载激光雷达数据与河水流动的时间序列中提取期间1986至2017年实地观察和信息，我们调查所有（（a）的空间分布变化的P。黑-dominated）木本植被和的甲。香草孤单; （b）河床地形是否可以与这些变化的空间分布相关联；以及（c）我们考虑A是否。incana在其空间和地形分布中显示出任何特殊特征，这可能表明它正在补充P的物理工程作用。老黑。我们证明了一个。藤本植物主要沿河道，岛屿和洪泛区边缘成直线生长，与以P为主的林区接壤。老黑和支持A的地区。印第安那与河床的地形发展有关。我们得出结论，A。incana似乎是P的补充物理工程师。老黑，这表明具有不同生活史特征的物种可能会通过对其他河床环境中的地貌发育产生影响来实现类似的互补河床物理工程。