Abstract

In European rivers, one of the most invasive of terrestrial plant species, Reynoutria japonica Houtt. (Polygonaceae), is frequently found at the water-land interface. In this study, ecological effects of native species replacement by this invasive species was explored. In particular, we examined changes in leaf litter composition, and the subsequent impacts of their decomposition on riparian and in-stream plant community growth. We compared leaf litter from two riparian species, native Rubus fruticosus L. agg. (Rosaceae) and its spontaneous substitute along river corridors, R. japonica. Effects were assessed through phytotoxicity tests on (1) a terrestrial model plant species, the lettuce Lactuca sativa var. capitata L. (Asteraceae) and (2) a typical semi-aquatic riparian plant species growing in the same riparian zone, the watercress Nasturtium officinale R.Br. (Brassicaceae). Seedling root length measurement permitted calculation of a root length reduction index. The experiment was performed over a six-month decomposition period, with samples taken at five time intervals. Phytotoxic abilities of R. japonica were inconsistent over the decomposition period, leading to breaks in the regulatory processes of the structuring native species, R. fruticosus. Decomposition of R. japonica leaf litter led to the unexpected emergence of successive competition and facilitation interactions. This study showed distinct phytotoxic impacts from R. japonica leaf litter decomposition, causing ecological effects that differed from that of native species. In a context where R. japonica progressively replaces native riparian species, such impacts need to be considered further as R. japonica phytotoxicity does not steadily prevent other species with offset phenologies to establish, including invasive species.

Graphic Abstract

中文翻译：

---

河岸系统中天然植物物种的替代对生态的影响：日本雷诺氏菌的意想不到的影响。落叶

摘要

在欧洲河流中，入侵性最大的陆生植物物种之一日本雷诺（Reynoutria japonica Houtt）。（Po科）经常在水-陆界面处发现。在这项研究中，探索了这种入侵物种替代本地物种的生态效应。特别是，我们研究了叶子凋落物组成的变化，以及它们分解对河岸和河内植物群落生长的后续影响。我们比较了来自两个河岸物种，本地的悬钩子属fruticosus L. agg的凋落物。蔷薇科（蔷薇科）及其沿河走廊的自发替代物，日本粳稻。通过植物毒性试验评估对（1）一种陆生模型植物物种莴苣莴苣变种（Lactuca sativa var）的影响。卡塔塔L.（菊科）和（2）在同一河岸带生长的典型半水河岸植物种，豆瓣菜金莲花。（十字花科）。幼苗根长测量允许计算根长减少指数。实验在六个月的分解期内进行，并以五个时间间隔进行采样。R. japonica在分解期间的植物毒性能力不一致，从而导致构造天然物种R. fruticosus的调节过程中断。粳稻叶片凋落物的分解导致连续竞争和促进相互作用的意外出现。这项研究显示了来自粳稻叶片凋落物分解，引起的生态效应不同于本地物种。在粳稻逐渐取代本地河岸物种的情况下，需要进一步考虑此类影响，因为粳稻的植物毒性并不能稳定地阻止其他具有偏移物候的物种的建立，包括入侵物种。

图形摘要