Scots Pine and Norway Spruce Wood Properties at Sites with Different Stand Densities

Abstract

Background and Objectives: The aim of this study was to determine the effects of different stand densities on wood density (WD), global modulus of elasticity (MOE), and bending strength (MOR) in 35-year-old Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst) stands, representing the hemiboreal forest zone. Materials and Methods: Scots pine and Norway spruce sites, representing different stand densities of 3000–3100; 2000–2100 and 1000–1100 trees per hectare, were chosen. Visually healthy model pine and spruce trees were selected, and diameter at breast height (DBH) was measured for model trees; the competition index was calculated; the MOE and MOR were evaluated by the Standards EN 408:2006 and EN 384:2016, at 12% moisture content; WD and the knot diameter were measured; and the strength class of wood was determined by the Standard EN 338:2009. To predict wood quality characteristics based on stand and tree characteristics, linear regression models were developed. Results and Conclusions: Higher stand density led to a significant change in the main wood properties of both conifer species. The highest mean WD, MOE, and MOR were obtained at the sites with the highest stand density. The MOE and MOR were highly correlated, but relatively weak correlations were found between MOE and MOR with tree DBH and WD. Despite the lower quality of Scots pine wood, the Norway spruce wood from more dense sites corresponded to the strength class of C16, according the strength grading of softwoods. The linear regression models did not perform well in describing the relationship of wood properties with stand and tree characteristics. The models for MOR accounted for the highest variation of 62–65% for both Scots pine and Norway spruce. These relationships can be expected to change with increased stand age or with the inclusion of specific crown parameters.

Management of Maritime Pine: Energetic Potential with Alternative Silvicultural Guidelines

“…concluded that higher stand density associated with high thinning intensity led to a significant change of the main wood properties for conifer species. The highest mean basic density, modulus of elasticity (MOE), and modulus of rupture (MOR) were obtained in the sites with the highest stand density followed by heavy thinning [28][29][30][31][32].…”

The Technical Quality of Wood of Scots Pine (<em>Pinus sylvestris </em>L.) of Diverse Genetic Origin

“…The mean value of this index is 9015 MPa [29], 10080 MPa [30]. The highest stand density MOE mean is increasing [31].…”

Analysis of Mechanical Behavior through Digital Image Correlation and Reliability of Pinus halepensis Mill.

“…To address this issue, the standard UNE 56535: 1977 [10] (updated in 2017) establishes the bases for the necessary testing to determine MOR c from a simple compression test. In addition, the standard UNE-EN 408: 2011 + A1: 2012 [11] establishes the bases for the determination of the modulus of of 23 elasticity in static bending (MOE f ) using conventional techniques for the measurement of deformations (i.e., strain gauges or electrical resistance strain sensors) during a static bending test [12][13][14][15]. However, these are invasive and destructive methods because, for test data collection, the sensors must penetrate into the material and be fixed by an adhesive element.…”