Biomass and Bioenergy 21 (2001) 401–405 Biomass equations and estimation for Gmelina arborea and Nauclea diderrichii stands in Akure forest reserve J.A. Fuwape ∗ , J.C. Onyekwelu, V.A.J. Adekunle Department of Forestry and Wood Technology, Federal University of Technology, P.M.B. 704, Akure, Nigeria Received 13 October 1999; received in revised form 8 May 2001; accepted 12 June 2001 Abstract Biomass estimation was carried out for even-aged stands of Gmelina arborea and Nauclea diderrichii in Akure forest reserve. Linear and allometric regression equations for biomass prediction were developed for trees of both species. The yield of each species and total above-ground biomass (TAGB) were estimated and compared. The various equations developed were assessed based on high coecient of determination (R 2 ), signicant F -ratio, and small Furnival index (FI) to select appropriate equation for prediction. The t -test shows a signicant dierence when the total volume and total dry weight of both species were compared, Gmelina arborea having a greater value than Nauclea diderrichii in both cases. The total volume of Gmelina arborea per hectare was 721:40m 3 and 265:18m 3 for Nauclea diderrichii. The TAGB for Gmelina arborea was 264;762 kg= ha and 88; 293 kg= ha for Nauclea diderrichii.c 2001 Elsevier Science Ltd. All rights reserved. Keywords: Biomass equation; Gmelina arborea; Nauclea diderrichi; Dry matter yield 1. Introduction The increasing desire for total tree utilization and the need to express yield in terms of weight rather than volume has stimulated studies of biomass production. Weight is more directly relevant for estimating trans- portation and other handling cost. Biomass data are also being used in predicting primary productivity, nu- trient distribution and nutrient loss due to biomass re- moval in timber logging and other non-timber forest product exploitation [1]. There is an acute scarcity of forest biomass for tim- ber, rewood and other wood products in semi-arid and arid parts of Africa due to slow growth of most ∗ Corresponding author. indigenous tree species [2]. In order to improve the availability of wood and subsequently reduce defor- estation due to over-exploitation of forest, the estab- lishment of high-yield hardwood plantations under intensive culture has been introduced [3]. Gmelina arborea is one of the fast growing exotic species widely grown in Nigeria for pulp while Naucleadider- richii is one of the few indigenous species that can thrive under plantation management. In this study, regression equations were developed for biomass of tree components expressed as a func- tion of easily measured parameters such as diame- ter at breast height, basal area, height or number of trees per hectare. These equations can be used to pre- dict biomass component [4]. This study also compared the volume and total above ground biomass (TAGB) 0961-9534/01/$-see front matter c 2001 Elsevier Science Ltd. All rights reserved. PII:S0961-9534(01)00036-8