Effect of Plantation Density on Some Physical and Technological Parameters of Scots Pine (Pinus sylvestris L.)

Abstract

The issue of optimising the initial stand density (ISD) of tree plantations has high practical importance. The objective of this study was to non-destructively evaluate the influence of the initial stand density of Scots pine (Pinus sylvestris L.) plantations located in the European part of the Russian Federation on wood basic density (BD), moisture content (MC), ultrasound velocity (UV), latewood content, and drilling resistance (DR). The trees at the age of 45 years with initial plantation densities of 500, 1000, 3000, 5000, and 10,000 trees/ha were tested by a 5 cm-long core sample for gravimetric MCGM and BD by PULSAR-2.2 for UV along the height (UVH) and through the tree trunk diameter (UVD) by the IML-RESI PD-400 tool for DR, as well as by GANN HT 85T for MC based on the electrical-resistance method (MCERM). A significant influence of ISD was found on DBH, UVD, MCGM, and MCERM. ISD had no significant impact on BD, UVH, and DR. The wood BD ranged from 356 to 578 kg·m−3 with a mean value of 434 ± 3.3 kg·m−3 and was restricted by the soil and environmental factors. DBH and 70% MCERM were good indicators of tree vitality. Linear correlations between DBH and MCERM (R2 = 0.67), DBH and MCGM (R2 = 0.74), DR and BD (R2 = 0.71), and the two-factor model MCGM = f(DBH, BD) with R2 = 0.76 were found.