Department of Physical Geography, Faculty of Geosciences, Utrecht University, 3508 TC Utrecht, the Netherlands; Department Coastal Systems, Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, the Netherlands; Department of Aquatic Ecology & Environmental Biology, Institute for Water and Wetland Research, Radboud University, Faculty of Science, P.O. Box 9010, 6500 GL Nijmegen, the Netherlands.
Department of Physical Geography, Faculty of Geosciences, Utrecht University, 3508 TC Utrecht, the Netherlands; Department Coastal Systems, Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, the Netherlands.
Sci Total Environ. 2024 Nov 10;950:175254. doi: 10.1016/j.scitotenv.2024.175254. Epub 2024 Aug 5.
Small uninhabited islands form important roosting and breeding habitats for many coastal birds. Previous studies have demonstrated that guano can promote ecosystem productivity and functionality on island ecosystems. Here, we assess the role of external nutrient input by coastal birds on the vegetation structure and coverage on sandy biogeomorphic islands, where island-forming processes depend on vegetation-sedimentation feedbacks. As a first step, we investigated whether breeding birds affect vegetation productivity on sandy back-barrier islands in the Wadden Sea. Using a combination of bird observations and plant stable isotope (δN) analyses, we demonstrate that (i) breeding birds transport large quantities of nutrients via their faecal outputs to these islands annually and that (ii) this external nitrogen source influences vegetation development on these sandy, nutrient-limited, islands. Based on these results we discuss how this avian nutrient pump could impact island development and habitat suitability for coastal birds and discuss future directions for research. In general, we conclude that avian subsidies have the potential to affect both the ecological and biogeomorphic functioning of coastal soft-sediment systems. However, the strength and scale of especially these biogeomorphic interactions are not fully understood. For the conservation of both threatened coastal birds and sandy back-barrier islands and the design of appropriate management strategies, we argue that three-way interactions between birds, vegetation and sandy island morphodynamics need to be further elucidated.
无人居住的小岛是许多沿海鸟类重要的栖息地和繁殖地。先前的研究表明，鸟粪可以促进岛屿生态系统的生态系统生产力和功能。在这里，我们评估了沿海鸟类对沙质生物地貌岛屿植被结构和覆盖度的外部营养输入的作用，而岛屿形成过程依赖于植被-沉降反馈。作为第一步，我们调查了繁殖鸟类是否会影响瓦登海沙质后滨障壁岛上的植被生产力。通过鸟类观察和植物稳定同位素（δN）分析的结合，我们证明：（i）繁殖鸟类每年通过粪便向这些岛屿输送大量的养分；（ii）这种外部氮源影响了这些沙质、养分有限的岛屿上的植被发育。基于这些结果，我们讨论了这种鸟类营养泵如何影响岛屿的发展和沿海鸟类的栖息地适宜性，并讨论了未来的研究方向。总的来说，我们得出结论，鸟类的补贴有可能影响沿海软泥沙系统的生态和生物地貌功能。然而，特别是这些生物地貌相互作用的强度和规模还不完全清楚。为了保护受到威胁的沿海鸟类和沙质后滨障壁岛屿，并制定适当的管理策略，我们认为需要进一步阐明鸟类、植被和沙质岛屿地貌动态之间的三向相互作用。
