Wood Porosity: A Universal Parameter for Dendroclimatic Analysis.

Abstract

Annual rings of conifers conventionally serve as a reliable indicator of climatic changes, whereas methods of such analyses are poorly developed for diffuse-porous species, such as the common aspen Populus tremula L. PiC densitometry was proposed as a new approach based on algorithmic analysis of the wood porosity distribution across the annual ring. Scotch pine Pinus sylvestris L. and aspen samples were used in the study. The method included measurement of the annual ring widths, anatomical analysis of the wood microstructure, and image processing to construct porosity profiles. Basic differences in porosity dynamics were observed between the species. In pine, porosity decreased by 70% from earlywood to latewood, reflecting a seasonal reduction in water supply. In aspen, the respective change did not exceed 20%, indicating a stable water demand throughout the season. Dendroclimatic analysis showed that pine radial growth was most sensitive to May-June precipitation, while temperatures during the same period were the key factor in aspen. PiC densitometry expands the possibilities of dendrochronological studies, allowing the use of diffuse-porous species for climate reconstruction and assessment of the climate effect on the wood structure.