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Estimation of individual tree volume and biomass is important for assessing removal of green house gases potential of the cashew trees and therefore provide a useful tool for the emerging carbon credit market mechanisms. The aim of this study was to estimate volume and biomass stocks of Anacardiumoccidentale L. grown in Coast Regions, Tanzania. Woodlots inventory data were collected from Liwale and Kisarawe districsts in Lindi and Coast regions respectively. A total of 45 cashew trees of varying dimensions were sampled for the study, covering a Dbh range between 2 and 89 cm. Non-linear models were used to regress observed biomass of stems, branches, twigs, total aboveground and below ground against Dbh or a combination of Dbh and total tree height, similar approach was applied to estimate cashew tree volume. Farm area was measured with the aid of GPS, and in the established plot of 0.008ha, tallest tree, medium and shortest tree heights were measured, for other trees only Dbh was measured. Four model forms (MFs) were fitted using data from 45 trees. MF 1 and 2 with one parameter variable (Dbh and Dbh2) were recommended. Biomass stocks for aboveground was estimated using equation AGB = Exp(-0.1684+0.8873lnDbh2) where R2, RMSE, RSE was 82.68%, 359.2 and 0.4738 respectively. Below ground, BBG=Exp(-2.3765 + 0.9394lnDbh2) where R2, RMSE and RSE was 85.53%, 54.7319, 0.4675 respectively; and total tree volume was estimated using equation V= Exp(-9.4111 + 2.6044lnDbh) where R2, RMSE and RSE was 84.35%, 3.593, and 0.6477 respectively. Biomass stocks from these tree components were converted to C stocks assuming 47% of biomass is C. Carbon stock was 34.41 4.96tC/ha, and the stand volume was found to be 48.88 11.67m3/ha. Developed models are recommended for use in similar site, conditions and species. |
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