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Since the beginning of the twentieth century the atmospheric concentration of carbon dioxide has
increased due to combustion of fossil fuel and deforestation. Green plants absorb CO2 from the
atmospherethrough photosynthesis. Investigating the effects of increasing atmospheric carbon dioxide on
tree species are important as trees playa major role in maintaining the ecological balance. Carbon'
sequestrationcapacity of trees which influence carbon absorption rate include, temperature, precipitation,
soil,slope,elevating site conditions, growth rates age and forest type.
Twentysix years old even aged Pinus caribaea (Morelet) plantation in Yagirala Forest Reserve was
selectedto this project. Pinus caribaea is a fast growing an exotic species. The main objectives of this
project(i) to quantify the amount of carbon in pine plantation of Yagirala Forest Reserve and other pine
plantationsof Sri Lanka, (ii) to build up a relationship of stem carbon with the stem biomass and volume
and (iii) to build up a relationship between above ground carbon and above ground biomass for the
selectedpine plantation in Yagirala Forest Reserve.
Threeplots were randomly selected representing all three sites, i.e., valley, slope and ridge top. 0.05 ha
circularplots were used for collecting data. Stem biomass, volume, height and dbh data for individual
trees in sample plots were obtained from a previous study carried out by Haripriya, (2003). Canopy
biomassof trees was calculated assuming the pine canopy is a cone. Carbon composition is different in
variousparts of the tree. Therefore carbon was determined for all parts of each tree separately by using
walkeryand Black method.
Carboncontent was more than half of the biomass in the Pinus caribaea in Yagirala forest pine plantation
andleaveshave the highest carbon content per unit mass. According to the results, the carbon content of
Pinus caribaea in Yagirala forest is 103.63 metric tons and carbon content of pine plantations of Sri Lanka
is 1,719,182 metric tons. Further regression analysis was carried to build the empirical models to predict
the stemcarbon and above ground carbon from stem biomass, stem volume, total height and diameter at
breast height. In order to select the best model, R2 and residual distribution were tested. Finally the
followingmodels were selected to predict stem carbon of Pinus caribaea in Yagirala pine plantation. rc
1
= 0.755rm; JC = 17.8JV ;rc = 4.30 Jh - 188 -. The following models were selected to use to
d
predictthe above ground carbon content of Pinus caribaea in the Yagirala Forest Reserve. rc =
0.777.r,;, ; c = 364V and log C = 1.60 log d. Where, C = amount of carbon (kg), m = biomass (kg),
V=stem volume, h=total height, d=diameter at breast height.
