DIVERSITY AND DISTRIBUTION PATTERN OF ALIEN PLANT SPECIES ALONG THE ALTITUDINAL GRADIENT IN DISTRICT PAURI, UTTARAKHAND, INDIA

Abstract

Human activities are involved in direct destruction of habitats. Next to man alien invasive plants are major threats to natural ecosystem. The present study attempts to understand baseline information which can measure future effects of climate change and anthropogenic changes on vegetation in mountain areas. The observed pattern of associations between species distribution and elevation zones is likely to help in understanding the possible effects of climate change and its impact in alien plant species distributions shifting towards higher altitudes. Maximum alien species distribution is found at 1600 to 2000 m (amsl) in the study site. A total of 82 plant species under 72 genera, belonging to 39 families are identified as alien plant species based on extensive field observations, herbarium and literature consultations. Distribution of invasive species based on growth form shows that the maximum number of exotic species contribution in the study area are herbs (56%), followed by shrubs(20%), and trees (24%). Among these Tropical American native species contribute 26%, South American native species contribute 21%, and African, European species each realm respectively contribute 9%, 8%. In the study area 67% alien species are naturalized and 33% species are casual. There is an increasing concern among foresters, ecologists, botanists, conservationists, and policy makers about the threat of uncontrolled introduction of alien aggressive, invasive plant species.