PDF(Pubmed)
Abstract：
Wetland habitats are changing under multiple anthropogenic pressures. Nutrient leakage and pollution modify physico-chemical state of wetlands and affect the ecosystem through bottom-up processes, while alien predators affect the ecosystems in a top-down manner. Boreal wetlands are important breeding areas for several waterbird species, the abundances of which potentially reflect both bottom-up and top-down ecosystem processes. Here, we use long-term national monitoring data gathered from c. 130 waterbird breeding sites in Finland from the 1980s to the 2020s. We hypothesised that the physico-chemical state of the waters and increasing alien predator abundance both play a role in steering the waterbird population trends. We set out to test this hypothesis by relating population changes of 17 waterbird species to changes in water chemistry and to regional alien predator indices while allowing species-specific effects to vary with foraging niche (dabblers, invertivore divers, piscivorous divers, herbivores), nesting site, female mass and habitat (oligotrophic, eutrophic). We found niche and nesting site-specific, habitat-dependent changes in waterbird numbers. While the associations with higher phosphorus levels and browning water were in overall positive at the oligotrophic lakes, the numbers of invertivore and piscivore diving ducks were most strongly negatively associated with higher phosphorus levels and browning water at the eutrophic lakes. Furthermore, increased pH levels benefitted piscivores. Invertivore diving duck species nesting on the wetlands had declined most on sites with high alien predator indices. Large herbivorous species and species preferring oligotrophic lakes seem to be successful. We conclude that the large-scale breeding waterbird decline in Finland is closely connected to both bottom-up and top-down processes, where negative associations are emphasised especially at eutrophic lakes. Niche-, nest site- and habitat-specific management actions are required to conserve declining waterbird populations. Managing wetlands on catchments level together with alien predator control may provide important approaches to future wetland management.
摘要：
湿地栖息地在多种人为压力下正在发生变化。养分泄漏和污染改变了湿地的物理化学状态，并通过自下而上的过程影响了生态系统。而外星掠食者以自上而下的方式影响生态系统。北方湿地是几种水鸟的重要繁殖地,其丰度可能反映了自下而上和自上而下的生态系统过程。这里,我们使用从c收集的长期国家监测数据。从1980年代到2020年代，芬兰的130个水鸟繁殖地。我们假设水域的物理化学状态和外星捕食者的丰度增加都在指导水鸟种群趋势方面发挥作用。我们着手通过将17种水鸟物种的种群变化与水化学变化和区域外来捕食者指数联系起来来检验这一假设，同时允许特定物种的影响随觅食利基而变化（涉水者，反向潜水员，食鱼潜水员,食草动物)，嵌套站点，女性群体和栖息地(贫营养，富营养化）。我们发现了特定的利基和嵌套位置，取决于栖息地的水鸟数量变化。尽管在贫营养湖泊中，与较高的磷水平和褐变水的关联总体上呈正相关，在富营养化的湖泊中，反浮游鸭和piscivore潜水鸭的数量与较高的磷水平和褐变的水呈最强烈的负相关。此外，增加的pH值有利于食性动物。在外来捕食者指数较高的地点，在湿地上筑巢的Invertivore潜水鸭物种数量下降幅度最大。大型食草物种和偏爱贫营养湖泊的物种似乎是成功的。我们得出的结论是，芬兰大规模繁殖水鸟的减少与自下而上和自上而下的过程密切相关，尤其是在富营养化的湖泊中强调负关联。Niche-,需要采取针对巢穴和栖息地的管理措施来保护不断下降的水鸟种群。在集水区一级管理湿地以及外来捕食者控制可能为未来的湿地管理提供重要方法。
