We examined differences in the responses of deciduous and evergreen broadleaved trees to fluvial disturbance and light environment near a river-facing forest edge in order to identify the factors limiting the distribution of deciduous trees, which are important components of warm-temperate mountainous riparian forests. Deciduous trees tended to be distributed on lower terraces of less than 2-m relative elevation from the water level, which corresponded with sites suffering from strong bank erosion due to high flood frequency. On the other hand, evergreen trees showed an opposite trend of distribution, indicating that high flood frequency associated with strong erosion-dominated soil disturbances might be a constraint for their establishment and/or survival. Furthermore, crowns of deciduous trees tended to be in the canopy layer at the forest edge, with fewer individuals observed beneath the canopy of evergreen trees, even at the forest edge. In contrast, evergreen trees were concentrated in the understory of the forest interior. These observations suggested that the light environment is the predominant factor affecting the establishment and survival of deciduous trees in warm-temperate mountainous riparian forests; however, the river-facing forest edge beneath the evergreen canopy is not a suitable habitat for deciduous trees. We concluded that erosion-dominated soil disturbance on lower terraces provides suitable habitats for deciduous trees by facilitating their reaching the canopy layer by limiting the establishment and/or survival of evergreen trees.

中文翻译：

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限制温带山区河岸森林落叶阔叶树分布的因素

我们研究了落叶和常绿阔叶树对河流干扰森林边缘附近的河流干扰和光照环境的响应差异，以发现限制落叶树分布的因素，这些因素是温带山区河岸森林的重要组成部分。落叶乔木往往分布在距水平面相对高度不到2 m的较低阶地上，这对应于因洪水频率高而遭受强烈河岸侵蚀的地点。另一方面，常绿乔木显示相反的分布趋势，表明高洪水频率与强侵蚀为主的土壤扰动有关，可能会限制其立足和/或生存。此外，落叶乔木的树冠倾向于在森林边缘的冠层中，在常绿乔木树冠下，甚至在森林边缘，观察到的个体也更少。相反，常绿乔木集中在森林内部的底层。这些观察结果表明，光照环境是影响温带山区河岸森林落叶树的建立和生存的主要因素。但是，常绿树冠下的面向河流的森林边缘不是落叶乔木的合适栖息地。我们得出的结论是，较低阶地的侵蚀占主导的土壤扰动通过限制常绿乔木的建立和/或存活，促进落叶乔木到达冠层，从而为落叶乔木提供了合适的栖息地。常绿的树木集中在森林内部的底层。这些观察结果表明，光照环境是影响温带山区河岸森林落叶树的建立和生存的主要因素。但是，常绿树冠下的面向河流的森林边缘不是落叶乔木的合适栖息地。我们得出的结论是，较低阶地的侵蚀占主导的土壤扰动通过限制常绿乔木的建立和/或存活，促进落叶乔木到达冠层，从而为落叶乔木提供了合适的栖息地。常绿的树木集中在森林内部的底层。这些观察结果表明，光照环境是影响温带山区河岸森林落叶树的建立和生存的主要因素。但是，常绿树冠下的面向河流的森林边缘不是落叶乔木的合适栖息地。我们得出的结论是，较低阶地的侵蚀占主导的土壤扰动通过限制常绿乔木的建立和/或存活，促进落叶乔木到达冠层，从而为落叶乔木提供了合适的栖息地。常绿树冠下的面向河流的森林边缘不适合落叶乔木。我们得出的结论是，较低阶地的侵蚀占主导的土壤扰动通过限制常绿乔木的建立和/或存活，促进落叶乔木到达冠层，从而为落叶乔木提供了合适的栖息地。常绿树冠下的面向河流的森林边缘不适合用作落叶乔木。我们得出的结论是，较低阶地的侵蚀占主导的土壤扰动通过限制常绿乔木的建立和/或存活，促进落叶乔木到达冠层，从而为落叶乔木提供了合适的栖息地。