Stand biomass and volume estimation for Miombo woodlands at Kitulangalo, Morogoro, Tanzania

Abstract

SYNOPSISTree volume and biomass equations developed for Kitulangalo area in Morogoro, Tanzania ignored small branches and small trees. Consequently, this study was carried out to develop new individual tree volume and biomass equations, and assess current regeneration status, biodiversity and yield ofmiombo woodlands of the area. Volume and biomass equations based on stump diameter for the estimation of volume and biomass of felled trees were also developed. A total of 30 trees were measured for stump diameter (StD), diameter at breast height (dbh) and total height and felled for the determination of volume and biomass. Different tree stem, branch and total volume and biomass models were then fitted.For the determination of current regeneration status, biodiversity and yield, data were collected from three strata: (a) Forest Reserve managed by the Central Government, (b) Forest Reserve under Sokoine University of Agriculture (SUA) and (c) General land (free access by the public). In each stratum, temporary concentric circular sample plots were laid out on transects at 150 m intervals for a 1% sampling intensity. Stand variables such as number of stems per ha, basal area, biomass, volume and plant diversity, were computed for each stratum. The study has revealed the presence of average volumes (m 3 ha· 1 ) and basal areas (m 2 ha· 1 ) of: 76.02 ± 9.14 and 9.13 ± 0.78 for the Government forest reserve, 76.03 ± 9.34 and 8.95 ± 0.73 for SUA forest reserve, and 43.9 ± 7.75 and 7.78 ± 1.1 for general land forest. The respective biomass values were 43.56 ± 7.06, 41.40 ± 4.90 and 29.31 ± 6.56 t ha· 1 • Tree species composition and regeneration status revealed that though disturbed, the public land species composition is not different from the other two strata. More studies should be done on the nursing ofthe abundant regeneration in the disturbed general land. The developed volume and biomass models are recommended to be used for the miombo woodlands at Kitulangalo area especially where small trees ( < 8 em dbh) are involved.

Allometric Models Based on Bayesian Frameworks Give Better Estimates of Aboveground Biomass in the Miombo Woodlands

“…Our findings that height and/or crown area does not substantially improve the predictive power of diameter models contradict recent findings in Peru, which show that crown radius greatly improves model performance, especially for the largest trees [35]. The majority of allometric models in the miombo ecoregion use DBH as the sole predictor variable, e.g., Chamshama et al [22], Ryan et al [21] Chidumayo et al [8] and Mugasha et al [23]. There are few models that include height as a second variable to DBH, e.g., Chamshama et al [22].…”

“…The accuracy of the models varied across the evaluated sites and trees of different diameter classes (Figure 3). In the absence of local or country-specific allometric models, mixed species models by Chamshama et al [22] and Ryan et al [21] appear as the most appropriate for estimating aboveground biomass in Kasungu and Neno, which were both dominated by small diameter trees. Breaking down the error into DBH size classes showed that all published models overestimated biomass with a greater bias in trees with a DBH greater than 30 cm.…”

“…The majority of allometric models in the miombo ecoregion use DBH as the sole predictor variable, e.g., Chamshama et al [22], Ryan et al [21] Chidumayo et al [8] and Mugasha et al [23]. There are few models that include height as a second variable to DBH, e.g., Chamshama et al [22]. The lack of models that include height and The power law model (Model 1) was better than the polynomial model with DBH and square of DBH.…”

“…The majority of allometric models in the miombo ecoregion use DBH as the sole predictor variable, e.g., Chamshama et al [22], Ryan et al [21] Chidumayo et al [8] and Mugasha et al [23]. There are few models that include height as a second variable to DBH, e.g., Chamshama et al [22]. The lack of models that include height and crown area may be attributed to difficulties associated with measuring these variables and an inability to measure them accurately-errors are pronounced for taller trees and trees with intersecting crowns [36]-and to the marginal value in improving the accuracy of allometric models when included as predictor variables along with DBH [33,37].…”

Review on Forest Carbon Stock and Suggestion for Carbon Release in Ethiopia

“…There are a figure of database and magazine that in attendance nonpayment weakening equations, stratified by rainfall government and section [16,19,20]. These failures to pay equations, based on a huge sample of vegetation, are frequently practical as the age group of confined allometric equations is over and over again not reasonable.…”