DIAMETER AT BREAST HEIGHT: AN INDEX OF TREE VOLUME ESTIMATION IN BLOCK A FOREST OF INTERNATIONAL INSTITUTE OF TROPICAL AGRICULTURE (IITA), IBADAN, OYO STATE, NIGERIA

Nigeria Nigerian Journal of Forestry, 49 (2) 110 - 119

Ariyo, O. C., Usman, M. B., Emeghara, U. U. and Ariyo, M. O. (2019)

Abstract
Tree volume is one of many parameters that are measured to document the size of individual trees. Tree volume measurements serve a variety of purposes, some economic, some scientific, and some for sporting competitions. This study was based on the relationship between tree volumes (V) and diameter at breast height (dbh). The volume equation of tree developed by FORMECU was adopted for this study. The study was conducted in the Block A forest of International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria to estimate the volume of trees in the forest using dbh. Data were collected by identifying; enumerating and measuring all the trees with dbh ≥ 10 cm in 30 plots laid along 3 transect D, E (00N) and F (1800W). The data were analysed using descriptive statistics, basal area analysis and volume equation. The result revealed 389 trees and shrubs per 0.3 hectare, belonging to 68 species and 27 families were recorded in the forest. The most abundant family are Fabaceae sub families of Caesalpinoideae, Mimosoideae and Papilinoideae represented by 12 species (17.64%). Newbouldia laevis (33), Lecaniodiscus cupanioides (28), Antiaris toxicaria var. africana (26) and Sterculia tragacantha (22), Albizia zygia (19), Cola millenii (18), and Trichlla monadelpha (16) were the most abundant trees in the forest. Daniellia orgea had the highest basal area and volume of 14.03 m2 ha−1 and 1.87 m3/ ha, followed by Lannea welwitchii, Cleistopholis patens and Ficus mucoso with 10.61 m2 ha−1, 8.59 m2 ha−1 and 6.07 m2 ha−1 basal area and 1.81 m3/ ha, 1.76 m3/ ha, 1.68 m3/ ha volume respectively. The study concludes that tree volumes could be computed from diameter at breast height without actual felling of the trees and without causing indelible damage to the tree or nearby understory.

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