PAPER TITLE :CHANGES IN SPECIES DIVERSITY, COMPOSITION, GROWTH AND REPRODUCTIVE PARAMETERS OF NATIVE VEGETATION INVADED BY CHROMOLAENA ODORATA AND TITHONIA DIVERSIFOLIA IN OSUN STATE, SOUTHWEST NIGERIA

FUTA JOURNAL OF RESEARCH IN SCIENCE | VOLUME 11 NUMBER 2 2015

Paper Details

  • Author(s) : O.O. Agboola1 and J.I. Muoghalu
  • Abstract:

Chromolaena odorata (L.) King & H.E. Robins and Tithonia diversifolia (Hemsl.) A.Gray are highly aggressive invaders in many parts of the tropics, especially in South-West Nigeria. The impact of both species on the diversity and floristic compositions of native species was evaluated. Relative to the uninvaded (control) plots, the average number of plant species in Chromolaena and Tithonia invaded plots was reduced by 31.6 % and 25.4 % respectively; Shannon-Wiener diversity was reduced by 13 % and 27 % respectively; species evenness was reduced by 10.5 % and 24.9 % respectively. Sorensen similarity of index between invaded and uninvaded plots for Chromolaena and Tithonia were 43.8 % and 32.6 % respectively. The number of native species was greatly reduced in areas invaded by C. odorata than in T. diversifolia invaded areas, leading to reduced species diversity and evenness. Reproductive parameters including mean number of flowers per plant, mean number of fruits per plant, mean number of seeds per fruit, mean weight of seeds and mean weight of each seed of the native species in the uninvaded plots were higher than those of the invaded plots for Tithonia diversifolia and Chromolaena odorata. The height of all native species in the uninvaded plots were taller than those of the invaded plots for T. diversifolia and C. odorata. It was concluded that invasion by C. odorata and T. diversifolia greatly affected the diversity of the native plant species with a corresponding reduction in their growth and reproductive parameters. Keywords: Height, Evenness, Species diversity, Impact, invasion