REDUCTION OF WOOD BASIC DENSITY IN DECAYED GREY ALDER STEMS

Abstract

This pilot study aims to estimate the impact of the internal stem decay on wood basic density in grey alder stems. Accurate estimates of stem biomass are crucial in reducing the uncertainty in the estimation of forest stand biomass. The density data were obtained from 21 decayed trees and from 15 healthy trees as reference sampled in five forest stands in Latvia. In total, the densities of 401 intact wood, 212 discoloured wood and 117 spongy rot specimens were measured obtained from the cross-cut discs of sampled trees. The Kruskal Wallis test was used to determine the statistically significant differences between mean values of intact wood, discoloured wood and spongy rot basic density. Our analysis revealed that mean basic density of intact wood differed significantly (p < 0.01) from the mean values of discoloured wood – 361.3 kg m^-3 and spongy rot – 240.9 kg m^-3 suggesting that decrease in wood density due to the internal decay must be taken into account for the stem biomass calculations. Our findings indicate that spongy rot incidence varied strongly between individual forest stands, from 2.4% – 80.9%. Other studies have confirmed that not only the density but also the carbon content of wood varies by its decomposition process.