Assessment of Species Richness and Diversity in the Nnamdi Azikiwe University Conservation Forest, Awka
Main Article Content
Abstract
Biodiversity assessment, particularly plant species richness and diversity, is essential for understanding ecosystem stability and resilience, yet many tropical forest studies underrepresent total plant diversity by focusing mainly on canopy species. This limitation is especially evident in secondary and institutional forests, where understory vegetation plays a critical but often overlooked ecological role. This study assessed plant species richness, diversity, and vegetation structure in the Nnamdi Azikiwe University Conservation Forest, Awka, Nigeria, using an integrated approach that captured both woody and understory vegetation. A stratified ecological survey design was employed. The Point-Centered Quarter Method (PCQM) was used to sample trees and shrubs, while 1 m² quadrats assessed understory vegetation, including herbs, grasses, climbers, and creepers. Eighteen systematically distributed sampling points were established along a central transect, and 72 quadrats were analyzed. Species diversity was quantified using the Shannon–Wiener index (H′), Simpson’s dominance index (D), and evenness (E). The study recorded high species richness across vegetation layers, confirming the forest’s status as a biologically diverse secondary ecosystem. Shannon–Wiener diversity values were high for woody (H′ = 3.672) and understory vegetation (H′ = 3.089). Evenness values were also high (E = 0.949 and 0.849), indicating balanced species distribution. However, low Simpson’s dominance values (D = 0.033 and 0.064) revealed dominance by a few species, particularly disturbance-tolerant taxa such as Chromolaena odorata and Alchornea cordifolia. Vegetation structure analysis showed a heterogeneous, multi-layered forest with active regeneration and an intermediate successional stage. These findings demonstrate that integrating understory vegetation improves biodiversity assessment and provides baseline ecological data for long-term monitoring and conservation.
Article Details
This work is licensed under a Creative Commons Attribution 4.0 International License.
References
Ekwealor, K. U., Iroka, C. F., Ukpaka, G. C., Okeke, P. N., Okafor, P. N. and Okereke, K. E. (2020b). An investigation on the forest and savanna vegetation types in Nnamdi Azikiwe University, Awka Campus, in Anambra State of Nigeria. Natural Resources and Conservation, 8(1), 7–18. https://doi.org/10.13189/nrc.2020.080102
FAO and UNEP (2020). State of the world’s forests 2020: Forests, biodiversity and people. Rome: Food and Agriculture Organization of the United Nations.
Iroka, C. F., Ekwealor, K. U., Onyili, C. A., Nwaogaranya, P. U., Nwakuche, A. O.,
Mbaukwu, O. A., Okereke, C. N. and Ikegbunam, C. N. (2025). Taxonomic
assessment of diversity of tree and shrub species in three tropical forest sites in Anambra State, Nigeria. Natural Resources and Conservation, 11(2), 22–37. https://doi.org/10.13189/nrc.2025.110202
Jakovac, C. C., Junqueira, A. B., Crouzeilles, R., Peña-Claros, M., Mesquita, R. C. G., and Bongers, F. (2021). The role of land-use history in driving successional pathways and its implications for the restoration of tropical forests. Biological reviews of the Cambridge Philosophical Society, 96(4), 1114–1134. https://doi.org/10.1111/brv.12694
Liu, J., Bai, X., Yin, Y., Wang, W., Li, Z. and Ma, P. (2021a). Spatial patterns and associations of tree species at different developmental stages in a montane secondary temperate forest of northeastern China. PeerJ, 9, e11517. https://doi.org/10.7717/peerj.11517
Liu, J., Zhao, Y.-P., Si, X., Feng, G., Slik, F., & Zhang, J. (2021b). University campuses as valuable resources for urban biodiversity research and conservation. Urban Forestry & Urban Greening, 64, Article 127255. https://doi.org/10.1016/j.ufug.2021.127255
Magurran, A. E. (2004). Measuring biological diversity. Oxford: Blackwell Science.
Mitchell, K. (2007). Quantitative analysis by the point-centered quarter method. Geneva, New York: Department of Mathematics and Computer Science, Hobart and William Smith Colleges. https://arxiv.org
Okeke, F. I., Ezenwenyi, C. U. and Okafor, C. N. (2021). Floristic diversity of forest fragments in southeastern Nigeria: Implications for conservation planning. Nigerian Journal of Ecology, 20(1), 33–48.
Okeke, U. C., Eze, B. E., and Chukwuma, E. C. (2022). Assessment of open grown tree species diversity in Nnamdi Azikiwe University, Awka, Nigeria. Journal of Agriculture and Ecology Research International, 23(1), 1–12.
Okoronkwo, O., Ekwealor, K. U., Okereke, N. C. and Iroka, C. F. (2024). Evaluating species diversity and ecological health of Nnamdi Azikiwe University Forest, Awka, Nigeria. Asian Journal of Environment and Ecology, 23(9), 50–65.
Onyekwelu, J. C. and Olusola, J. A. (2021). Anthropogenic disturbance and tree species dominance in tropical forest reserves of southern Nigeria. Forest Ecology and Management, 489, 119075.
Onyekwelu, J. C., Mosandl, R., Stimm, B., and Lawal, A. (2026). Vegetation characteristics and biodiversity conservation potentials of three forest categories in Nigerian rainforest ecosystem. Tropical Ecology. 67, 214–226. https://doi.org/10.1007/s42965-026-00424-0
Perea, R., Schroeder, J. W. and Dirzo, R. (2022). The herbaceous understory plant community in the context of the overstory: An overlooked component of tropical diversity. Diversity, 14(10), 800. https://doi.org/10.3390/d14100800
Poorter, L., van der Sande, M. T., Amissah, L., Bongers, F., Hordijk, I., Kok, J., Laurance, S. G. W., Martínez-Ramos, M., Matsuo, T., Meave, J. A., Muñoz, R., Peña-Claros, M., van Breugel, M., Herault, B., Jakovac, C. C., Lebrija-Trejos, E., Norden, N., & Lohbeck, M. (2024). A comprehensive framework for vegetation succession. Ecosphere, 15(4), Article e4794. https://doi.org/10.1002/ecs2.4794