Bidens pilosa (Asteraceae) invasion reshapes the pattern of plant communities and edaphic properties across the north-western Himalayan landscape

Abstract

Development and economic growth, coupled with climate change and other environmental shifts, have made the unique and pristine mountainous regions vulnerable to plant invasions. While the effects of exotic plant invasions on community structure have been extensively studied in the lowlands, there is a dearth of such research in the altitudinal ecosystems. The objective of the present study was to investigate the ecological impact of Bidens pilosa (blackjack, Beggars tick; Asteraceae) on vegetation and soil dynamics across the north-western Himalayan landscape. Vegetation and soil sampling were conducted in paired invaded and control quadrats along an altitudinal gradient (300–1500 m asl) in the outer Himalayan region of Kangra, Himachal Pradesh, India. The presence of B. pilosa has a notable impact on reducing alpha diversity, with a more pronounced effect observed above 600 m asl. Pairwise beta diversity indices indicate that the invasion of B. pilosa has changed the natural species composition above 700 m asl, likely due to species turnover (i.e., species replacement). The results of NMDS and PERMANOVA analyses further support the notion that the invasion of B. pilosa has considerably homogenized the species composition along the selected elevational gradient. Further, significant variations in most of the soil parameters between the two invasion classes were observed within the elevation range of 600–1200 m asl. Overall, the results indicate that invasion by B. pilosa reshaped the patterns of floristic composition and soil properties in the north-western Himalayan landscape, leading to biotic and edaphic homogenization across an altitudinal gradient. The most substantial impact was noticed above the altitudinal range of 600 m asl, indicating that B. pilosa prefers mildly temperate climates over tropical ones in the studied area. It is pertinent to monitor and control the spread of B. pilosa in the Himalayan ecosystem to ensure the conservation of its unique biodiversity.