Henkel Stefanie, Richter Ronny, Andraczek Karl, Mundry Roger, Dontschev Madeleine, Engelmann Rolf A, Hartmann Timo, Hecht Christian, Kasperidus Hans Dieter, Rieland Georg, Scholz Mathias, Seele-Dilbat Carolin, Vieweg Michael, Wirth Christian
Systematic Botany and Functional Biodiversity, Institute for Biology, Leipzig University, Johannisallee 21, 04103, Leipzig, Germany.
Department of Conservation Biology and Social-Ecological Systems, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318, Leipzig, Germany.
Sci Rep. 2025 Mar 24;15(1):10117. doi: 10.1038/s41598-025-92079-5.
Floodplain forests are currently undergoing substantial reorganization processes due to the combined effects of management-induced altered hydrological conditions, climate change and novel invasive pathogens. Nowadays, the ash dieback is one of the most concerning diseases affecting European floodplain forests, causing substantial tree mortality and threatening the loss of the dominant key tree species of the hardwood floodplain forest, Fraxinus excelsior. Understanding how the increased light availability caused by pathogen-driven mortality in combination with altered hydrological conditions and climate change affects growth responses in a diverse forest community is of crucial importance for conservation efforts. Thus, we examined growth of the main tree species in response to ash dieback and how it depended on altered hydrological conditions under novel climatic conditions for the lower and upper canopy in the floodplain forest of Leipzig, Germany. Our study period encompassed the consecutive drought years from 2018 to 2020. We found that tree growth responded mostly positively to increased light availability, but only on moist sites, while tree growth largely declined on dry sites, suggesting that water availability is a critical factor for tree species to be able to benefit from increased light availability due to canopy disturbances caused by ash dieback. This hydrological effect was species-specific in the lower canopy but not in the upper canopy. While, in the lower canopy, some species such as the competitive shade-tolerant but flood-intolerant Acer pseudoplatanus and Acer platanoides benefited from ash dieback on moist sites, others were less affected or suffered disproportionally, indicating that floodplain forests might turn into a novel ecosystem dominated by competitive Acer species, which may have detrimental effects on ecosystem functioning. Our results give hints on floodplain forests of the future and have important implications for conservation measures, suggesting that a substantial revitalization of natural hydrological dynamics is important to maintain a tree composition that resembles the existing one and thus sustain their conservation status.
由于管理导致的水文条件改变、气候变化和新型入侵病原体的综合影响，洪泛平原森林目前正在经历重大的重组过程。如今，白蜡树枯梢病是影响欧洲洪泛平原森林最令人担忧的疾病之一，它导致大量树木死亡，并威胁到硬木洪泛平原森林的主要关键树种——欧洲白蜡树的丧失。了解病原体导致的死亡率增加所带来的光照增加，与水文条件改变和气候变化相结合，如何影响多样化森林群落中的生长反应，对于保护工作至关重要。因此，我们研究了德国莱比锡洪泛平原森林中，主要树种对白蜡树枯梢病的生长反应，以及在新的气候条件下，它如何依赖于改变的水文条件，涉及下层和上层树冠。我们的研究期涵盖了2018年至2020年连续的干旱年份。我们发现，树木生长大多对光照增加呈积极反应，但仅在湿润的地点如此，而在干燥地点树木生长大幅下降，这表明水分供应是树种能够从白蜡树枯梢病导致的树冠干扰所增加的光照中受益的关键因素。这种水文效应在下层树冠中具有物种特异性，但在上层树冠中并非如此。在下层树冠中，一些物种，如具有竞争力的耐荫但不耐洪的假挪威槭和挪威槭，在湿润地点受益于白蜡树枯梢病，而其他物种受影响较小或遭受不成比例的影响，这表明洪泛平原森林可能会变成一个由具有竞争力的槭属物种主导的新型生态系统，这可能对生态系统功能产生不利影响。我们的结果为未来的洪泛平原森林提供了线索，并对保护措施具有重要意义，表明大力恢复自然水文动态对于维持类似于现有树木组成的结构从而保持其保护状态至关重要。
