Structural and functional organization in natural young stand of Scots pine (Pinus sylvestris L.) in the 9-aged cuttings of Pinetum vacciniosum located on the Middle Ural

Abstract

The study of structural and functional organization of young pine stands is one of the pressing problems of modern forestry. The spatial pattern of pine stands naturally recovering 9 years after clear-cutting in the lingonberry pine forest type at the Middle Urals was studied. The establishing a trial plot, selecting model trees, determination basic wood density, assessing trees ranking and analyzing the variability of biometric indicators were fulfilled using appropriate methods. For model trees, trunk height as well as diameter of trunk in bark and without bark were measured at 0.1, 0.2...0.9 of relative heights. Trunk volumes of model pine trees were calculated using the simple and complex Huber formula. It was established that 9 years after clear-cutting the structure of the pine young growth in the lingonberry pine forest was similar to the spatial pattern previously established for pine young growth in the berry pine forest and the mixed-grass pine forest. Natural regeneration of pine trees at the felled areas in lingonberry pine forests continued for several years. Pine trees at the felled areas were at the age of 3-8 years. A very high level of variability in biometric parameters and trunk volumes in the bark of young pine trees has been established. In general, the distribution of biometric indicators was significantly different from normal. Ranking trees according to height classes made it possible to significantly reduce the level of variability in the diameter, height, and volume of the trunk in the bark. Analysis of model trees revealed that the discrepancies between trunk volume values in the bark and without the bark, determined by the complex Huber formula and the Huber median section formula, did not exceed ± 5.0%. However, the percentage of discrepancy increases gradually with decreasing density of young growth. In young pine trees the bark content increases significantly with a decrease in density of young growth. In very dense young growth, the bark content is approximately 1/12 of the total trunk volume. In areas with practically no undergrowth, the volume of the bark reaches almost 1/3 of the total trunk volume. It has been established that most of the wood reserves, in tree trunks both with bark and without bark, are found in very dense young growth. Basic density of the wood gradually decreased from the base to the top of the tree trunk. The values of the basic density of the wood and the nature of its change according to the relative heights of the trunk were the practically same in all variants of young growth density.