Influence of Initial Stand Density, Age, and Growing Conditions on Anatomical Parameters and Wood Basic Density of Scots Pine (Pinus sylvestris L.)

Wood density is one of the most important parameters characterizing the technical quality of the material and prod- ucts and varies within a relatively large range. The objective of the study was to evaluate the effect of the initial stand density, age and growing conditions of Scots pine (Pinus sylvestris L.) trees on basic density, and anatomical parameters of wood. Core samples were taken from growing trees from eight experimental plots (Mari El Republic, Russian Federation) with different initial stand densities: 500, 1000, 3000, 5000, and 10,000 trees per ha and tree ages: 30, 45, and 120 years. The stereometric method was used to assess the wood basic density on cores (20–25 repetitions per plot) and wood microstructure parameters (10 repetitions per plot): the number of tracheid rows in the early and latewood, cell wall thickness, and lumen area were measured using microscope images of wood cross-section slices. The number of tracheid rows in the earlywood had the highest variation while the variation of tracheid rows in the latewood was twice less. The lumen area of cells also varied significantly, especially in latewood. The thickness of tracheid cells in trees varied the least, this value was almost the same in both wood layers. Wood basic density interacted with the number of tracheid rows in earlywood and latewood (R2 = .85). The variation of tracheid parameters that eventually determine wood density occurs in a tree in response to changing environmental conditions due to the self-regulation mechanism of tree vital processes aimed at increasing its vitality in the prevailing environmental conditions.