Invasive Species Hit Global South Hardest

A global analysis has overturned a long-standing assumption about invasive species, finding that their greatest biodiversity impacts occur not in wealthier nations of the Global North but across the Global South, where rapidly developing economies, weak governance, and limited management capacity leave ecosystems most vulnerable to biological invasions. The spread of invasive alien species (IAS) is a major driver of global biodiversity loss. It's estimated that invasive species have contributed to roughly 60% of documented species extinctions and hundreds of billions of dollars in economic damages. Although the global distribution of non-native species is increasingly well documented, the geographic pattern of their environmental impacts remains poorly understood. Most global assessments rely on indirect indicators, such as invasive species richness or trade volume, which have suggested that impacts are greatest in the Global North. However, this pattern may reflect underreporting in the Global South rather than true differences in ecological impact. Here, Sven Bacher and colleagues combined the Global Impacts Dataset of Invasive Alien Species (GIDIAS), which compiles more than 22,000 documented impacts from more than 3,300 invasive species across 172 countries, with global datasets of alien species distributions. To account for differences in research effort across countries, Bacher et al. developed a new metric – average impact severity – which estimates the severity of the documented impacts, and then used regression analyses to further identify the social, economic, and governance factors associated with higher impacts. The findings suggest that average IAS impact severity is 34% higher in the Global South (where research effort is generally lower), despite the Global North having more than twice as many impact reports. The highest impacts occur in emerging economies, where high economic activity increases opportunities for species introductions while weak governance and limited management capacity reduce the ability to prevent or respond to invasions. The findings also show that stronger governance is associated with lower IAS impacts, suggesting that improved governance can substantially reduce invasion impacts.