Biomass Conversion and Expansion Factors for Young Norway Spruce (Picea abies (L.) Karst.) Trees Planted on Non-Forest Lands in Eastern Carpathians

Abstract

In this study biomass conversion and expansion factors (BCEFs) were developed for young Norway spruce trees planted on non-forest lands, in order to support quantification of carbon stock changes in biomass pools of afforestation works. Regression models for stem volume and stem wood density were also developed. The data set included 250 trees collected from 25 plantations between 1 and 12 years old, located in the Eastern Carpathians of Romania. The study shows that BCEFs decreased with increasing tree dimensions, following an exponential trend. In all proposed models the highest prediction was reached when both variables considered (i.e. root-collar diameter and height) were used together. However, used separately, height produced a slightly higher prediction compared to root-collar diameter. Stem volume was well predicted by both root-collar diameter and height. Anyway, a significant improvement in prediction resulted when both variables were used together. Stem wood density decreased sharply with the increase of the two tree dimensions used as variables.