Effects of precommercial thinning on growth parameters in Pinus nigra Arn. subsp. pallasiana (Lamb.) Holmboe stand

Abstract

We investigated the effects of precommercial thinning (PCT) applied at different levels on the growth parameters of natural Anatolian black pine stand. The experimental site was located in the province of Isparta in southern Turkey. PCT was set up using a randomized complete block design with three replicates and three treatments (control, 2–2.5 m × 2–2.5 m and 3–3.5 m × 3–3.5 m spacing). The experimental plots were established in March 2014. At the end of the growing seasons for three years (2014–2016), growth parameters such as diameter, height and crown radius were measured. PCT was found to be significantly effective on diameter, height, individual tree basal area, and crown radius increment at the end of the third year (p < 0.05). While diameter, individual tree basal area and crown radius increment increased with increasing PCT intensity, height increment was higher in control than PCT. Although the PCT treatments applied with 3–3.5 m spacing affected individual tree development positively, we need long-term results on wood quality and yield. According to the short-term results, it is thought that it is better to lower the stand closeness gradually, so, it may be advisable to apply PCT by 2–2.5 m × 2–2.5 m spacing.