Complementary approaches to identify, characterize and prioritize invasive plants in a biodiversity hotspot

Abstract

Prioritising invasive species is crucial for managing invasions and mitigating impacts on biodiversity globally, yet most efforts are concentrated in the Global North, with significant gaps in the Global South. In the absence of region-specific assessments, land managers in the Global South often rely on broad global priority frameworks, whose relevance at smaller spatial scales remains uncertain. In addition to of spatial scale, robust prioritisation frameworks should incorporate multiple dimensions of species distribution and impact. To help fill this gap, in this study we used complementary approaches: herbarium-based and expert assessments to evaluate the distribution and impact of invasive plant species in a biodiversity hotspot in India. We scored species across different dimensions of impact, and generated a composite score that was used to rank and prioritise the invasive species. To understand the concordance of rankings across scales, we compared our regional rankings with national and global rankings for these species. We identified seventy-nine invasive plant species in the Northern Western Ghats and Konkan region, which revealed a ten-fold difference in their spatial extent. Expert assessments indicated that only few species had high scores across the different distribution and impact dimensions, while most had low to moderate scores. The results show that distribution-related dimensions were correlated, but impact-associated dimensions remained independent, highlighting the need to include both in prioritisation frameworks. Although most regional species were included in national and global invasive species lists, their priority rankings differed at these different scales. Overall, our study underscores the importance of integrating both distribution and impact dimensions for species prioritisation and highlights the importance of local-scale assessments for effective invasive species management.