Tree species diversity, biomass production and carbon stock of three forest management types in Benue State, Nigeria
Date
2025
Authors
Journal Title
Journal ISSN
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Publisher
Federal University of Technology, Owerri
Abstract
Carbon stocks can be conserved or increased by the sustainable management of existing forest types. However, anthropogenic activities and poor forest management can adversely affect biomass production and carbon storage. Published information on biomass and carbon storage potentials of different forest management types is scanty, especially in the study area. To this end, this study assessed the tree species diversity, soil properties, volume estimation, biomass and carbon storage of three forest management types (Community Forest Area (CFA), Forest Reserve (FR), and Sacred Grove (SG)) in Benue State, Nigeria. A nested plot design was adopted for data collection. Each nested plot comprises 35 m x 35 m, 25 m x 25 m, 7 m x 7 m, and 1 m x 1 m square plots. The 35 m x 35 m area was the main plot within which all trees with a Dbh of 40 cm and above were measured. The 25 m x 25 m subplot was laid within the main plot, and all trees with Dbh between 20 cm and 40 cm were measured. Within each subplot, a sub-subplot of 7 m x 7 m was laid for the enumeration of trees with a Dbh range of 5 m to 20 cm. A quadrat of 2 m x 2m was laid within the 7 x 7 m plots to assess low vegetation with a diameter <5 cm. A square frame of 1 m x 1m was laid to assess all litter. An experienced forest-type management taxonomist identified all live tree species. Tree growth variables (diameters at the base, breast height, middle, and top of the tree and tree total heights) were measured on all live trees, standing dead and lying dead trees in all plots. An indirect method of biomass estimation was used in this study. Tree core samples were collected at tree breast height (1.3m) using an increment borer. Data were analyzed using descriptive (mean, frequencies, and standard deviations) and inferential (analysis of variance, T-test and Pearson correlation) statistics. A cumulative total of 1,881 individual trees were enumerated in the study area, with 749, 621, and 511 individual trees found under FR, SG, and CFA, respectively. A total of 73 tree species in 35 families were assessed in the study area, out of which CFA had 38 species from 25 families, FR had 28 species from 16 families, and SG had 35 species from 24 families. Most of the tree species were indigenous, with few exotic species (Gmelina arborea and Tectona grandis). Khaya senegalensis and Gmelina arborea were present across the three forest management types, with varied frequency of occurrence. The Family Importance Value Index (FIV) in CFA and SG indicated higher family density in these forest management types than in FR. A few families (Caesalpinioideae, Euphorbiaceae, Moraceae, and Fabaceae) were important across the forest management types. Malvaceae, Verbenaceae and Fabaceae were the most important families in CFA, FR and SG, respectively. Ty. The Shannon-Wiener index of 3.00, 2.11 and 2.97 were recorded under CFA, SG and FR, respectively and differed significantly. The Margalef richness index was highest (6.01) under CFA and lowest (4.11) under the FR. The highest evenness value of 0.55 was recorded under SG, and the lowest value (0.29) was under FR, indicating a high disparity in tree species richness. Gmelina arborea, Sterculia
Description
This thesis is for the award of Doctor of Philosophy (PhD.) in Forest Inventory and Biometrics
Keywords
Biomass production, carbon stock, tree species, forest management, forest resrves, carbon pools, Department of Forestry and Wood Technology
Citation
Dau, H. J. (2025). Tree species diversity, biomass production and carbon stock of three forest management types in Benue State, Nigeria [Unpublished Doctoral Thesis]. Federal University of Technology, Owerri, Nigeria