A comprehensive assessment reveals significant patterns and drivers of alien vertebrate species distribution across mountainous regions globally.
The diverse biotas of the world’s mountains face increasing threats, primarily due to climate change, land-use change, and particularly, biological invasions. Despite being understudied, these regions have become remarkable recipients of alien vertebrate species. A recent study compiled occurrence records for 717 alien vertebrate species distributed across 2984 mountains worldwide, analyzing their distribution, biogeographic origins, and the factors driving their richness.
Researchers found the most frequently recorded alien vertebrates were birds, with 318 species reported across 2595 mountains, followed by 161 species of mammals documented across 1518 mountains. Пalaearctic, Nearctic, and Australasian realms were identified as the most prevalent recipients of these species, whereas the Nearctic, Indo-Malay, and Afrotropic realms were the most common donors.
Interestingly, nearly half of the alien species appeared within protected areas, amplifying concerns over the potential impacts of invasions on mountain biotas located within these designated regions. Factors such as higher road densities, increased human population densities, and clusters of anthropogenic activities were found to contribute significantly to the distribution patterns of alien vertebrates.
The findings indicate human activities are exacerbated threats to mountains, areas recognized for their ecological importance due to the immense biodiversity they support. Higher road density, lower biodiversity intactness, and physical mountain characteristics like elevation ranges and terrain ruggedness correlated strongly with increased alien vertebrate richness.
These insights are particularly alarming as they suggest the alien species' presence is often accompanied by significant ecological ramifications. Proxies of anthropogenic impacts, such as the development of infrastructure supporting human activities, contribute to increased introductions and subsequent establishment of alien species.
Despite previous assumptions, the study highlighted the potential underestimation of invasions within tropical mountain regions, attributed to sampling bias predominantly centered on the Northern Hemisphere and Australia.
"Our large-scale assessment reveals the advance of alien vertebrates in mountains worldwide and urges attention to minimize the impacts of biological invasions on the exceptional mountain biotas," emphasized the authors of the article.
The documented record of alien species disparities across different taxonomic groups—from fishes, amphibians, and reptiles to mammals and birds—suggests specific focus areas for conservation efforts. The lack of adequate records for certain groups potentially masks the severity of the threat posed by these invasive species.
Overall, it is evident from this analysis, which surveyed data from various global initiatives and databases, including the DASCO dataset, the need for heightened awareness and action to mitigate the ecological risks associated with biological invasions.
Moving forward, targeted conservation strategies are imperative to preserve mountain ecosystems characterized by high levels of endemism and unique biodiversity. The results advocate for adaptive management practices—especially with rising tourism and new pressures related to climate change—that focus on reducing human impact and preserving the integrity of mountain habitats.
Efforts should also be directed at fostering research initiatives to achieve thorough documentation of existing species, focusing particularly on tropical mountains less represented within global studies. "The magnitude of invasions in tropical mountains could be underestimated due to sampling bias toward the Northern Hemisphere and Australia," noted the authors of the article.
This knowledge serves as both evidence of the challenges faced by mountain ecosystems and as a clarion call for collaborative global action to safeguard against the growing incidences of biological invasions threatening these fragile environments.