Наукові праці Лісівничої академії наук України (Jun 2020)
Larix kaempferi Carr. as a promising woody species for plantation forest growing in forest stands of the Western Forest-Steppe of Ukraine
Abstract
Based on the research results, material was obtained that reflects the main aspects of the growth and accumulation of Larix kaempferi wood in stands of var-ious types of forest growth conditions, of different composition and age. In the Western Forest-Steppe of Ukraine, L. kaempferi is characterized by a very high growth rate and competitiveness at a young age, displacing other tree species from the stands with different row spacing - 2.5 ... 4.0 m. It is not advis-able to introduce individual rows, individual seedlings, or links of seedlings of other tree species into larch cultures, since they are almost completely displaced from the composition by the age of 20 years, as a result of which larch receives additional space for the intensive development of the crowns. L. kaempferi has a tendency to form a powerful crown, which significantly reduces the quality of the trunk and its volume. At the same time, a fairly dense crown enables it to form steady-state, single-species artificial phytocoenoses of high productivity. Therefore, the negative property of the species to form a pow-erful crown can be eliminated by creating pure, dense stands. However, exceed-ingly dense plantations can be seriously damaged by various abiotic factors. Therefore, the initial placement of planting spots should be 2.0 × 1.3-1.5...3.0 × 1.0-1.5 m, taking into account the type of forest growth conditions, which corre-sponds to a density of 3.3...5. 0 pcs. ∙ ha-1. Timber volume depends on the number of larch trees in the plantation and varies significantly. Even in plantations with a predominance of larch (8-10 units), the stock of stem wood is relatively low and is also characterized by sig-nificant variability (272-406 m3 ∙ ha-1), which indicates a high intensity of inter-mediate use in larch forests of 35-40 years old age and lack of a specific ap-proach in relation to the use of these volumes. The larch accumulates the highest timber volume in the stands, where its participation in the composition is maxim-ized. In young and middle-aged stands of fresh fairly rich types of forest site con-ditions, L. kaempferi grows less intensively (Ia-Id site class), while in fresh and moist rich site conditions, the larch stand site class is significantly higher (Ib-Ie). Under the investigated forest growth conditions, after 50 years of age, larch sig-nificantly reduces growth in height, while the growth in diameter continues to in-crease. In pure stands, L. kaempferi accumulates high volumes of stem wood, alt-hough its average height and diameter are noticeably smaller than in mixed stands. At the same time, if the density of pure larch plantations is close to the optimum, the average mensurational indexes of conifers approach those in mixed plantations. The survival of the larch even in the initially pure plantations varies consid-erably. This is due to the different approaches to the intensity of tending felling. The absence of a specific program for growing larch plantations to establish a density that is close to optimal for different age periods is the cause of underutili-zation of the edaphic potential of various forest growth conditions and, as a re-sult, there is a shortage in supply of significant volumes of wood. As a promising object for plantation silviculture, L. kaempferi meets a num-ber of important requirements: intensive growth and rapid accumulation of stem wood; simple cultivation technology; relatively wide ecological amplitude, the possibility of cultivation in pure stands, valuable wood; resistance against pests and diseases; wide range of wood applications; the possibility of conducting in-tensive intermediate forest management.
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