Models for estimating tree volume, above-and belowground biomass for acacia-commiphora woodlands in Same district, Tanzania
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Date
2015
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Publisher
Sokoine University of Agriculture
Abstract
Reduced Emissions from Deforestation and Degradation (REDD) framework demands
measuring of carbon stock changes. In most cases, estimates of carbon stocks rely on
volume and biomass estimation allometric models. Although species-specific and some
generic models for biomass and volume estimation have been developed for some
vegetation types such as Miombo woodlands, their use in Acacia-Commiphora woodlands
in dry areas is questionable as they comprise short-height trees with small to medium tree
diameters scattered from each other. This necessitates the need to develop robust generic
allometric models that accounts for the heterogeneity of tree diversity in the Acacia-
Commiphora woodlands in dry areas. Allometric models for volume and biomass
estimation were developed by means of destructive sampling of 60 trees with DBH
distribution ranging from 2.50 to 30.30 cm. Four different model forms were tested and
the best model for estimating tree’s section biomass and volume were selected based on
the lowest values of Residual Standard Error (RSE) and Akaike Information Criterion
(AIC). All selected models had their parameter estimates significantly different from zero
(P<0.01). The best biomass and volume models were used to estimate total tree biomass
(above- and belowground) and tree volume at plot level. The estimated total tree biomass
and volume was 34.69 ± 2.42 t C/ha and 23.11 ± 1.64 m 3 ha -1 respectively which is
equivalent to carbon stock of 17.00 t C/ha. These estimates may be used to set a baseline
for computation of carbon stock changes which are useful not only for sustainable
management of the woodland but also for the implementation of REDD+ policy.
Description
Keywords
Acacia-Commiphora woodlands, Miombo woodlands, Reduced Emission, Deforestation, Carbon stocks, Tree volume, Biomas