Weed potential of Mikania micrantha H.B.K., and its control in fallows after shifting agriculture (Jhum) in North-East India

Abstract

Mikania micrantha H.B.K. is an exotic, perennial weed which colonizes communities developing after slash and burn agriculture (Jhum) at lower elevations of north-east India. The population dynamics and reproductive potential of M. micrantha was studied. Reproduction through ramets arising from rosettes exceeded that from seeds. The ramet population growth was highest during the monsoon season as a consequence of high population birth and large-scale mortality. Net population increased with increasing age of the fallow for 3 years, and declined drastically in 6- and 12-year-old fallows. Biomass was allocated mainly to the ramet root system in younger fallows and to the rosette root system in older fallows. Seed reproduction potential peaked in a 3-year-old fallow and declined rapidly thereafter. The significance of the results in terms of natural elimination of the species through succession, and the increased weed potential leading to arrested succession under short jhum cycles is discussed.