Species specific allometric equations, biomass expansion factor and wood density of native tree species in dry afromontane forest of Ethiopia

Abstract Forest is the second largest store house of carbon released from different sources. However, limited allometric equations are available to determine its contribution for carbon cycle. The objective of study was to develop species specific allometric equations, establish database for Biomass Expansion Factor (BEF) and Wood Density (WD) to five tree species, namely Apodytes dimidiata, Cassiopourea malosana, Celtis africana, Ilex mitis and Myrica salicifolia grown in dry afromontane forest of Ethiopia. The sampled tree diameter at breast height (dbh) and their total height (ht) ranged from 7 to 48 cm and 6.7 to 23.4 m respectively. A total of 62 sample trees harvested from different diameter classes of each species and divided in to different biomass compartments (stem, big branches > 7cm), small branches (2-7cm) and twigs and foliage (< 2cm). To determined WD, total of 186(stem position) and108 sample disks (big branches till 7cm dbh were sampled. Oven dried at temperature of 105oc and 70oc for 72 and 24hrs for wood and foliage respectively. A set of log transformed models relating total above ground biomass to dbh, ht, WD and average crown diameter as independent variables were fitted following R-software version 4.0.1. The best biomass models were found to be having lower AIC, residual standard error and higher adj.coefficient of determination. The BEF and WD of aforementioned tree species were ranged from1.19 to 1.40 and 0.53 to 0.74 gcm− 3 respectively. Species specific allometric equations were better than generalized allometric equation for estimation of above ground biomass of Chilimo dry afromontane forest.