Earlywood, latewood and total ring width of a ring-porous species (Fraxinus nigra Marsh) in relation to climatic and hydrologic factors

Fourteen black ash (Fraxinus nigra Marsh.) trees were measured for earlywood, latewood and total ring width. Standard dendrochronological procedures were applied and three mean index chronologies were computed. Results show that the earlywood chronology is more monotonous, as revealed by its lower sensitivity and standard deviation. Latewood and total ring-width chronologies are similar in showing higher signal-to-noise ratios, a higher agreement with the population chronology and higher variance in the first eigenvector than in the earlywood chronology. Latewood chronology, however, is more sensitive and has a higher standard deviation compared to earlywood and total ring-width chronologies. One interesting result concerns the significant positive relationship between latewood and total ring width of the current year (t) and the earlywood width in the following year (t+1). within the current year of growth there is no relationship between earlywood and latewood width. Response function analysis revealed that both earlywood and latewood responded to different environmental parameters; latewood and total ring-width chronologies exhibit no major differences. This study emphasizes the common signal included in latewood and total ring width. It also demonstrates the need to further assess the relationship between the finer structure in earlywood (vessel diameter and density, etc.) and the environmental conditions during earlywood development.