Amenity trees diversity in selected tertiary institutions within Port Harcourt Metropolis, Rivers State, Nigeria

A T Oladele ,F S Eguakun ,U.c Ugbaja

doi:10.4314/jasem.v24i12.25

Abstract

Trees are a central component of most urban communities, providing diverse benefits such as improving air quality, increasing aesthetic appeal, preventing erosion and providing habitat for wildlife. However, there is inadequate information on the distribution and diversity of these trees within our academic environments. This study investigates the distribution, frequency and species diversity of amenity trees within the main campuses of tertiary institutions in River State, Nigeria. The selected tertiary institutions are University of Port-Harcourt (Institution A) and Rivers State University (Institution B). Five (5) major roads in each campus were randomly selected, and 200m along each road was selected as sample areas. Ten (10) meter was marked from the edge of the road, and complete inventory was taken of all trees within the marked sample area. Diameter at breast height (DBH), crown diameter and tree height were measured. Shannon-Weiner and Simpson diversity index were used to calculate amenity trees diversity, while Margalef specie richness was used to calculate the species index. A total of 539 trees were surveyed on both campuses, comprising 26 different species and 10 families. Casuarina equisetifolia had the highest frequency with 92 trees in B. Simpson diversity index showed higher diversity (D = 0.78) in B amenity trees than A (D = 0.81). Shannon-Weiner species evenness was 0.71 and 0.76 for Institutions A and B respectively. Margalef specie richness index were 2.90 for A and 1.40 for B. This study provides baseline information for ecosystem management of urban forest tree species within campuses. For sustainable management of trees on campuses, frequent inventory and survey should be conducted to establish their abundance, distribution and diversity.

Highlights

Trees are a central component of most urban communities, providing diverse benefits such as improving air quality, increasing aesthetic appeal, preventing erosion and providing habitat for wildlife
Knowledge on tree species diversity and distribution would serve as baseline information to know the status of the tree species in the study area; which is basic in understanding regeneration processes, such as tree growth, tree mortality, under-storey development, and the spread of disturbances (Francisco et al, 2017)
To protect and prevent trees decline in our urban environment, it is essential to examine the current status of species diversity, composition and abundance of tree species as this will provide guidance for management and conservation

Summary

Introduction

Trees are a central component of most urban communities, providing diverse benefits such as improving air quality, increasing aesthetic appeal, preventing erosion and providing habitat for wildlife. This study investigates the distribution, frequency and species diversity of amenity trees within the main campuses of tertiary institutions in River State, Nigeria. This study provides baseline information for ecosystem management of urban forest tree species within campuses. This study is aimed at assessing tree species diversity and distribution within two tertiary institutions in Port Harcourt, Rivers State, Nigeria with the view to providing baseline information useful to developing conservation strategy. Data analysis: Plant population and species diversity were analyzed using the following species diversity indices: Shannon-Weiner Index of Diversity (H’) - Species diversity within the study area were analyzed using the diversity index of Shannon and Weaver (1949), the index varies depending on the number of species present It is higher when there are more species, indicating greater diversity. Shannon-Weiner Index of diversity (H’) was calculated following Kent and Coker (1992) and Magurran (2004):

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