Effect of growth conditions on wood properties of Scots pine (Pinus sylvestris L.)

The study material of Scots pine sample trees originated from five different forest site types (Cladonia, Calluna, Myrtillus, natural raised bog and drained raised bog) in Estonia. Altogether, 60 trees were sampled from 10 stands. From these, test disks and sample blocks (1.2 m in length) were cut at 1.3 m height, 1/2 of tree height and 3/4 of tree height. We analysed the effect of forest site type on the growth of tree ring width, proportion of late- and heartwood, oven-dry density, bending and compression strength and wood hardness. Wood properties in stands of the same age showed great variability. Significant differences were found in the wood properties between site types. Wood density and strength characteristics were higher in samples from heath site types than from the sites more optimal for pine (e.g., Myrtillus). The quality of the wood from peatland stands was lower than from trees grown on mineral soil. The decreasing trend in strength properties towards the top of trees was steeper in the wood formed under poor nutrient conditions. Latewood proportion increased with tree age. However, in the case of equal latewood percentages, heartwood density was higher than sapwood density.