Invasive alien plant species in Jigme Singye Wangchuck National Park, Bhutan: distribution patterns, invasion hotspots and management implications

Abstract

With ever-escalating human footprint, protected areas worldwide are witnessing pressing problem of plant invasions. Although recent research efforts have elucidated the patterns of plant invasions in protected areas from the developed world, yet such studies are still scarce from the developing world. This study presents the first assessment of invasive alien plant species (IAPS) in Jigme Singye Wangchuck National Park (JSWNP), Bhutan—a country located in the lap of the Himalaya. We laid 375 vegetation plots (10 × 10 m) along 16 transects, covering over 140 km inside the Park. The transects followed traditional footpaths, cattle tracks, and modern road networks to capture invasion patterns associated with disturbed habitats and linear infrastructure. We recorded 22 IAPS, including four listed among the world’s 100 worst invasive species. Ageratina adenophora was the most abundant and widespread species, occuring in over 66% of plots, followed by Solanum viarum, Bidens pilosa, Chromolaena odorata, and Oxalis latifolia. Species richness of IAPS was highest in the southeastern and southwestern lowland zones, particularly within the Tingtibi and Nabji ranges. Chi-square tests revealed significant associations of IAPS with altitude, disturbance, and habitat types, indicating that both environmental and anthropogenic factors influence their distribution. Spatial hotspot maps identified high-density invasion zones in disturbed and accessible areas. These findings provide a critical baseline for understanding IAPS spread in this Himalayan protected area and offer actionable insights for targeted management, early detection, and community-driven control strategies to safeguard native biodiversity.