Effect of retained trees on the development of young Scots pine stands in Southern Finland

Abstract

The purpose of the study was to examine the effect of retained Scots pine ( Pinus sylvestris L.) trees in the context of even-aged management systems on height, diameter growth, and branching of individual Scots pine seedlings and seedling stands in Southern Finland. A modeling and simulation approach was applied. Empirical models were constructed using data sets acquired from temporary sample plots in nine stands. The models were used to simulate tree height, diameter, and branch diameter growth. Results indicate that Scots pine trees retained in Scots pine seedling stands had not brought about unstocked or very poorly stocked patches around their bases in the study stands. Each retained tree of 25–40 cm in diameter reduced the height growth potential of Scots pine seedlings about 9–17% within a circle of 10 m radius. Retained tree competition did not result in reduced tree diameter for a given height. Retained tree influence on the diameter of the thickest branch of a seedling was rather small for practical applications, but the sum branch cross-sectional area was reduced, especially on fertile sites. In stand level simulations, the retention of 48 ha −1 trees of 25 cm average diameter and 21 m height on a rather poor site resulted in 15 years in about 5–7% decrease in seedling height, 6–8% decrease in diameter, and 2–5% decrease in maximum branch diameter compared to no retention, varying with the seedling stand density. The effect of the spatial pattern of retention in random, regular, or clustered structures on seedling growth was marginal.