Ageratina adenophora: its invasion and influence on the biodiversity of herbaceous vegetation in Girinagar Range of Paonta Forest Division, District Sirmour, Himachal Pradesh.
Invasion of an eco-system by the invasive species in Himachal Pradesh has taken serious dimensions all across the world and ever growing menace of it is posing serious threats even to the conservation and sustainable utilization of biodiversity along with significant impacts on the eco-system services provided by the dynamic forest ecosystem. The present study was conducted to assess the impact of Ageratina adenophora on herbaceous community in three different forest ecosystem i.e site-I (Pinus roxburgii forest), site-II (Pinus roxburgii+Shorea robusta) and site-III (open barren land) in Girinagar range of Paonta Forest Division. Study was conducted on the seasonal basis for a period of 2 years and the result obtained revealed that the number of species of herbaceous vegetation in the study area were getting reduced due to continous spread of Ageratina adenophora. Maximum spread of Ageratina adenophora was recorded during summer season (48.60%) whereas, minimum values of spread were noticed in winter season (46.83%). When compared amongst sites, it was observed that site I showed the maximum values (61.50%) followed by site III (52.02%). Minimum values of spread were recorded in site II (34.43%) during the period of investigation. It may also noticed that the IVI values of most of the associated plants like Bidens pilosa, Ageratum conyzoides, Parthenium hysterophorus present in study sites were reduced in the second year when compared to the values of first year of study. It was therefore revealed that the spread of Ageratina adenophora - an invasive species- from dense mono-specific stands over a period of time with little understorey thus, effecting the plant diversity of forest ecosystem.