CO2 fixation by Pinus sylvestris L. and Quercus pyrenaicaWilld. in «Pinar de Valsaín» and «Matas de Valsaín» stands

Abstract

Biomass and carbon dioxide accumulated amounts have been estimated in two Pinus sylvestris and Quercus pyrenaica forests («Matas de Valsaín» and «Pinar de Valsaín», Segovia). Data obtained in samplings made by CIFOR-INIA for both species have been utilized in this study. For each species, three trees per diameter class were selected, being then felled and separated into their biomass fractions (stems, branches with diameter over 7 cm, branches with diameter between 2 and 7 cm and branches thinner than 2 cm). Every tree fraction was weighed at field. The stump of one tree per diameter class was also extracted and weighed. Dry weights were determined at the laboratory through a sample of each fraction, and linear regression models to relate dry biomass with diameter for each biomass fraction were fitted. Using these models, a biomass table was constructed to be applied to inventory data (number of trees per diameter class) for determining total biomass within the stands. The CO2 fixed per biomass unit was calculated through the ratio biomass/carbon. Balances of net CO2 fixation have been determined knowing the annual increment and annual extractions.