The plant species composition, diversity and natural regeneration of indigenous trees in the disturbed Ruvu South Forest Reserve, Tanzania

Abstract

Ruvu Forest Reserve is among coastal forests in Tanzania that has been impacted by the increased anthropogenic activities. It was determined the plant species composition, diversity and indigenous trees regeneration growth size structure in the degraded Ruvu South Forest. Transect method was used to collect data that were treated using t-test. A total of 110 plant species distributed among 38 families were recorded such that Holarrhena pubescens, Hymenocardia ulmoides, Millettia micans, Ochna mossambicensis, Pseudolachnostylis maprouneifolia and Strychnos madagascariensis were the most common trees in moderately disturbed site, whereas Albizia versicolor, Pteleopsis myrtifolia, Pterocarpus angolensis, Antiaris toxicaria, Diplorhynchus condylocarpon and Terminalia kaiserana dominated in the highly disturbed site. The Shannon ' s diversity index (2.3 ± 0.06) was significantly higher in moderately disturbed sites than 2.1 ± 0.1 in the highly disturbed site. The poles/shrubs and coppices were the dominant growth sizes with no significant difference between sites than trees and seedlings of which their densities were significantly different between the two sites. Trees in highly disturbed sites had diameter sizes at breast height between 10cm and 40cm and beyond these sizes were missing because of selective exploitation as opposed to moderately disturbed site with representative individuals with diameter sizes beyond 50cm. These observations imply the negative impacts of anthropogenic activities on the plant community composition and the capacity to regeneration naturally under heavily degraded condition. Adequate interventions are necessary to allow the degraded Ruvu South Forest recover through natural regeneration to safeguard the coastal forests biodiversity.