Abstract

Tropical forests are increasingly affected by anthropogenic disturbance, which can alter plant species composition, abundance and community structure. This study assessed plant species composition, abundance, richness and diversity in disturbed and undisturbed forest patches in Egbema, Rivers State, Nigeria. Systematic sampling was conducted in five 50 m x 50 m plots in each forest condition, giving a total sampled area of 2.5 ha. Plant species were identified and their abundance recorded. Species richness was estimated using Margalefs richness index, while Simpson’s Index of Diversity was used to assess diversity. A total of 28 plant species were recorded, comprising 22 trees, three shrubs and three herbs. Nineteen species occurred in disturbed forest patches and 15 in undisturbed patches, with six species shared between the two conditions. The disturbed patches contained 355 individuals, compared with 312 individuals in the undisturbed patches. Chromolaena odorata was the most abundant species in the disturbed forest, with 80 individuals (22.54%), whereas Marantochloa leucantha was the most abundant species in the undisturbed forest, with 71 individuals (22.76%). Margalefs species richness was higher in disturbed patches (3.07) than in undisturbed patches (2.44). Simpson’s Index of Diversity was nearly identical between disturbed (0.8703) and undisturbed (0.8695) patches. The results demonstrate marked differences in floristic composition and species dominance between the two forest conditions, despite their similar Simpson diversity values. The greater richness recorded in disturbed patches was associated largely with pioneer and disturbance-associated species rather than with evidence of improved forest condition. Protection of remaining relatively intact forest patches and management of disturbed areas to promote native regeneration are therefore recommended.