Estimation of above ground biomass of a Pinus caribaea Morelet stand in lower Hantana

Above ground biomass production was estimated in a 25 year-old Pinus caribaea stand in the land belonging to the University of Peradeniya, in lower Hantana in the Central Province. Twenty four pine trees felled were used to collect data for developing allometric biomass equations and to estimate the above ground biomass. Empirical formulae were derived to estimate the above ground biomass separately for the cylindrical lower part and the conical upper part of the pine trees. Using these site-specific formulae derived from empirical data, the above ground biomass of the 25 year-old P. caribaea stand was found to be 194 t/ha. A second estimation of 136 t/ha for the above ground biomass was obtained using standard formulae. Of the live standing crop, the stem represented 60%, the branches 17%, leaves 13%, cones 3% and dead branches 7%. This pine stand had 695 pine trees/ha, a mean diameter at breast height (dbh) of 20.1 cm, a mean height of 20.7 m and mean basal area of 23.6 m(2)/ha. The estimated above ground biomass showed that the P caribaea plantation studied is a good sink for sequestered carbon. Since the study was based on actual measurements through destructive sampling, yielding more accurate estimates than from standard derivations, the derived empirical formulae in this study are recommended for estimation of the above ground biomass of comparable pine tree stands in the Hantana plantation and also other plantations in similar steeply undulating topography. Based on a meta-analysis of literature data on P. caribaea in the tropics, it was found that a P caribaea plantation up to an age of 25 years attains maximum above ground biomass when it reached ca. 22 years.