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

Abstract

Tree 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 of miombo 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 (m3ha-1) and basal areas (m2ha-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 of the 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 cm dbh) are involved.


Keywords: Miombo woodlands, Volume and biomass yields, Regeneration status and biodiversity


Southern African Forestry Journal No.200 2004: 59-70