Influence of the stand position on the slope and climate on latewood characteristics of Scots pine on dunes of South-West Estonia

Radial growth, latewood width and relationships between climatic variables and latewood width of Scots pines from stands of different age growing at different positions on the slopes of dunes (foot and top) were investigated in two study sites (Hdm-1 and Hdm-2) in the region of dunes in South-West Estonia. Analysis revealed no obvious regularity between tree-ring widths of pines on the top and at the foot of the dunes. Young pines showed a better radial growth at the foot. Old pines had a slightly larger average tree ring width on the top of the dunes. The average latewood width of young pines was significantly larger at the foot of the dunes. The position on the slope had no significant effect on the average latewood percentage in tree-rings. The average latewood width of the old pines was rather equal at both positions on the slope. The average latewood percentage in tree-rings was larger at the foot of the dunes. The slightly lesser latewood percentage observed in the case of the young stand was obviously related to the young age of this stand. The latewood width of young pines was not sensitive to the temperature conditions. The latewood width was positively correlated with mean monthly temperatures of December of the previous year and of June of the current season only at the foot of the slope. The high temperatures of the winter and spring months (January-June) had a positive and the warm August of the previous year a negative effect on the latewood formation in old pines in both positions. The latewood of old pines on the top of the dunes was more sensitive to the mean temperatures of the spring months and at the foot of the dunes, to the winter temperatures. Significant correlations between latewood width and precipitation were mostly observed in the case of the old pine stand. Precipitation in all months of the previous summer and autumn and in the winter months of the current year favoured latewood formation in both positions. The latewood width in the young stand was positively correlated with the precipitation in July of the current growth season but significantly only on the top of the dune.