Roadside Distribution Patterns of Invasive Alien Plants Along an Altitudinal Gradient in Arunachal Himalaya, India

Abstract Invasive plants have spread all over the world, including the Himalayan region. In 2009, the distribution pattern of invasive alien plants was studied on 38 plots, from 100 to 4200 m, in Arunachal Pradesh and Assam, India. Eighteen invasive alien plants (frequency >5%) from 7 families were recorded, of which 15 species (83.3%) were from North and South America. The most common plants by both frequency and coverage (>50%) were Ageratum conyzoides, Chromolaena odorata, and Mikania micrantha. Species composition changed with altitude. Thirteen species grew in the tropical zone, 10 in the subtropical, 6 in the temperate. and 1, Taraxacum officinale, in the subalpine zone. We suggest that low temperature and snowfall in the highlands may filter nonadapted species from tropical regions and that recent construction and use of roads facilitate the establishment of invasive alien plants. Although several invasive alien plants were regarded as noxious weeds, local residents in the study area mentioned thei...