Global status, trends, drivers and impacts of non-native plant species in mountain ecosystems

forthcoming

The current biodiversity crisis is characterized by unprecedented rates of species extinctions, and invasive species are one of the most important drivers of this loss. Yet, many invasive species were only recognized as such when already widely naturalized in a region. A major challenge is thus to identify which non-native species have the potential to spread into natural ecosystems and become invasive before their eradication becomes unfeasible. Mountain ecosystems remained comparatively natural and harbour high levels of unique biodiversity but are disproportionately affected by climate change. So far, they are considered to be only minimally affected by non-native species and are thus the frontiers of their distributions. Yet, many non-native plant species spread upslope along roads, from where they might continue to spread into the surrounding undisturbed habitats. Indeed, non-native plant species have been recorded in mountains on all populated continents, and might hence be substantially more widespread than assumed. However, due to data deficiency, it remains unknown whether non-native plant species already occur in undisturbed habitats, which species have the potential to spread and which drivers besides roads are decisive. Even less is known about their impacts in mountains and thus which species should be classified as invasive, as impacts are least investigated in mountains of all terrestrial habitats. This project will fill these knowledge gaps by integrating field observations, experiments and macroecological analyses based on so far untapped global monitoring data from all populated continents, ranging from valleys to the upper limits of plant life in disturbed to undisturbed habitats. It will conduct the first global quantification of the status, trends, drivers and impacts of non-native plant species in mountains. The outcomes have thus not only a high scientific relevance but are also essential for the conservation of the world’s biodiversity.