Floristic Composition and Diversity of Freshwater Swamp Forests in the Niger Basin of Nigeria

Nwabueze I Igu,Robert Marchant

doi:10.4236/ojf.2018.84035

Abstract

Freshwater swamp forests are wetland ecosystems with poorly understood ecology. With increasing degradation across the Niger basin (where it is the most extensive across West Africa), it is deemed important to understand its distribution, patterns and composition. This is aimed at both increasing botanical inventories in the ecosystem and also elucidate vital steps that could guide its effective conservation. This study assessed the floristic composition and diversity across 16 one hectare forest plots and sought to show how varied the sites were in terms of diversity, stem density and basal area. The survey showed that the area had 116 species within 82 genera and 36 families. The number of species found in each of the disturbed sites was generally higher than the intact forest sites, which was not diverse but comprised many trees with higher basal area. While the stem density which ranged from 94 - 409 stems·ha-1 is comparable with that of other tropical forests, species richness was low (ranging from 8.65 - 0.52). Diversity ranged from 3.38 - 0.98 and was higher in disturbed sites than in intact locations. Species richness was generally low and implies that loss of species in the ecosystem could threaten species’ existence and conservation in the ecosystem. Disturbed locations had more species than the intact zones and as such show the importance of targeted conservation not only in the undisturbed locations but also in the disturbed locations with a higher species value and potential for species stability of the ecosystem.

Highlights

Tropical ecosystems are the biologically richest ecosystem on earth (Pimm & Raven, 2000; Bradshaw et al, 2009; Gibson et al, 2011) and contain up to two third of the earth’s terrestrial biodiversity (Gardner et al, 2009)
The survey recorded a total of 116 species within 82 genera and 36 families across the 16 plots. As these hectares were from three different forest locations or sites, the results are presented according to the different forest sites below
While many species are found here, they are composed of three abundant species: Elaeis guineensis, Cleistopholis patens Engl. & Diels and Sterculia oblonga with Importance values of 52, 29.4 and 28 respectively (Appendix 1)

Summary

Introduction

Tropical ecosystems are the biologically richest ecosystem on earth (Pimm & Raven, 2000; Bradshaw et al, 2009; Gibson et al, 2011) and contain up to two third of the earth’s terrestrial biodiversity (Gardner et al, 2009) They are very productive ecosystem that provides significant benefits, a wide range of ecosystem services and sources of livelihood for a vast majority (Lewis, 2006; FAO, 2011). While these features make tropical ecosystems unique and sought after, they are being lost at alarming rates, without a detailed understanding of their specific ecosystems. The ecosystem borders other forest ecosystems like lowland rainforest and mangrove swamp forests (James, 2008); given their restricted environmental range, they are prone to fragmentation and disturbance

Objectives

Methods

Results

Discussion

Conclusion