International Journal of Research Studies in Biosciences (IJRSB) Volume 7, Issue 11, 2019, PP 1-9 ISSN No. (Online) 2349-0365 DOI: http://dx.doi.org/10.20431/2349-0365.0711001 www.arcjournals.org International Journal of Research Studies in Biosciences (IJRSB) Page | 1 Application of Diversity Indices in the Study of Trees and Shrubs of the Nun River Forest, Nigeria Felix Okponanabofa Youkparigha 1* , Dudutari Edmund Patani 2 1 Department of Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria 2 Department of Biological Sciences, Faculty of Science, Bayelsa Medical University, Yenagoa, Bayelsa State, Nigeria 1. INTRODUCTION Plants generally are an integral part of the ecosystem, and play several roles including protection, recreation, productivity, nutrition and medicine. Most plants, including shrubs and trees, have been reported to play essential roles in the control of soil erosion, contribute in the stabilization of climate among others. But in the recent times, the global forests have been decreasing due to several human factors including agricultural activities, urbanization, industrialization, population growth, bush burning (Izah et al., 2017, 2018, Izah and Seiyaboh, 2018a,b; Izah, 2018). During long term reversible or irreversible human activities in forest, its resources including plants and animals are affected with regard to their composition, distribution and abundance. Zhigila et al. (2015) and Fries and Herman (1990) reported that on annual basis about 294.020 square kilo metres of the world’s forests disappear. Close to 3 decades from this estimation, the global population has increased. As such, the diminishing rate of global forest could have far exceeded this approximation. In taxonomy (a branch of science involved in classification of organisms in a systematic manner), plants are classified into Divisions, Classes, Orders, Families (sometimes into sub-families), Genera Abstract: Nun River forest is one of the major forests in Bayelsa state. But due to industrialization the forest is being impacted by human activities. This study evaluated the trees and shrubs of the Nun River forest reserve in Bayelsa state, Nigeria using diversity indices. The study was carried out from 2008 - 2009 in the Nun River forest using random sampling techniques. Four 50m by 10m transects (50m apart) were laid, two on either side of a bush path. Each of the four plots was divided into five thus, 10m by 10m sub-plots. All trees and shrubs greater or equal to 2 metres (≥2 m) height in each sub-plot were identified by the assistance of foresters and identification guide. The study recorded a total of 29 trees and shrubs belonging to 18 families; Euphorbiaceae (had 4 species), Rubiaceae (had 3 species), Annonaceae, Apocynaceae, Irvingiaceae, Moraceae, Myristicaceae and Palmae (had 2 species each), while Ctenolophonaceae, Guttiferae, Lamiaceae, Loganiaceae, Malvaceae, Ochnaceae, Passifloraceae, Polygalaceae, Rutaceae and Salicaceae (had 1 species each). The ecosystem showed slight alteration in species richness based on Shannon Wiener index. Slight variation exists among the diversity indices across the various plots. Comparison of the diversity using t-test between the various plots showed that there is significant difference (p<0.05) in the interaction between Plot 3 – Plot 1, and Plot 2 – Plot 1. The Bellinger’s coefficient showed no major discontinuity in the horizontal distribution in the population status of each plot. Apart from the interaction of Plot 4 – Plot 3, Jaccard index values were > 0.5 or 50% critical values, while Sorenson quantitative index showed that the similarity is> 0.5 or 50% critical values for similarity except for interaction between Plot 4 – Plot 3 and Plot 4 – Plot 2, an indication of species similarity in the various locations. Hence, the distribution of individual trees and shrubs in the Nun River forest reserve in Bayelsa state is essential in assessing the size of the conservation units.. Keywords: Diversity indices, Nun River forest reserve, Shrubs, Trees *Corresponding Author: Felix Okponanabofa Youkparigha, Department of Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria