RELATIONSHIP BETWEEN STEM BIOMASS AND VOLUME OF Pinus caribaea IN THE YAGIRALA FOREST RESERVE

Abstract

The biomass is an important measurement in commercial forestry maintained to producepulp, paper, chips, fuel wood products etc. The estimation of the biomass of the tree is notan easy task and few studies were carried out so far.

The present study was conducted in the 25 years old Pinus caribaea plantation in YagiralaForest Reserve, which is in the low country wet zone. According to the geographicaldifferences in the plantation, i.e., valley, slopes and ridge, stratified random sampling wascarried out and two 0.05 ha circular plots were established in each stratum. Altogether 6plots were used for the data collection.

The diameter at breast height (dbh), total height were measured for all the trees in theseplots and after dividing the tree stem into several sections, the length and end and middiameters of each section was measured using the Spiegel relaskop.

The volume of the stem was estimated by calculating section volumes. Smalian's andNewton's formula were used to estimate the section volumes except for the final section atthe top, which was assumed as a cone. In order to save time, one plot was measured forNewton's formula and the rest was measured for Smalian's formula. Then a relationshipwas build to estimate Newton's volume (Ne) using Smalian's volume (Sm) as theexplanatory variable (equation I). The R2value was 99.9%.

Ne = 0.976 * Sm (1)

Biomass of the tree was estimated by extracting core samples at the breast height and midheight of the tree. The density of the core samples were estimated using oven dry weightand the green volume of the core samples. When tested, there was no significant differenceof the density along the stem. Therefore stem biomass was estimated using the density atthe breast height, and the total stem volume. Also there was no significant densitydifferences between three sites.

The regression analysis was used with the pooled data to find out the relationship betweenthe stem biomass (W) and the volume (V). Using variable of stem volume and the biomassand its tranformations developed the several models. The best model was selected bychecking the R2 value, standard residual distribution, modelling efficiency and bias. Thebest rclationshin for the hiOI1l;]SS :l1lrl YOIIl"lr ,,·:1< lhr rnll:l1;nn ') whir]' h·w 02 .... 1.. " nr