Структурні зміни букового (Fagus sylvatica L.) пралісу в контексті кліматично орієнтованого лісівництва

Abstract

Climate Smart Forestry is a modern forestry concept that aims to reduce the negative impacts of climate changes on forests and to develop a long-term forest management strategy that considers climate changes and natural disasters effects on forests. Structural changes in virgin forests are a natural response on climate changes and this justifies the importance of their study in the context of Climate Smart Forestry. The dynamics of the Common beech virgin forest in the Ukrainian Carpathians has been studied from 2000 to 2015 on a 10-hectares permanent plot in accordance with the IUFRO methodological guidelines as a joint effort with the Swiss Federal Institute of Forest, Snow and Landscape (WSL). Climate changes (increase in the sum of active temperatures – by 22 % and decrease in precipitation – by 46 %) recorded on the meteorological station of the Carpathian Biosphere Reserve, which is located 3 km away from the research plot, and the impact of windthrow – according to the data of 4 inventories. An analysis of the 15 years dynamics of virgin forest revealed significant changes in some forest stand parameters against the background of the overall stability of its structure. Investigation results confirmed that beech virgin forest of the Ukrainian Carpathians is a very complex forest stand (four layers, nine species, and fluctuation of the trees’ diameter – from 6 to 132 cm and the trees’ age – from 1 to 400 years), but very stable (variability of 6 out of 8 key parameters does not exceed 10 percent) too. The increase in the number of trees in the beech virgin forest from 2010 to 2015 was 60 % (from 278 to 445 trees per ha) and the main reason for this was the windfall in 2007. The increase in the diameter increment was also significant from 2005 to 2015 (by 35 % – from 0.26 to 0.36 cm/year), even in spite of the increase in the number of trees and the decrease in average diameter. The uprise of four new species (Rocky oak, Cherry, Mountain ash, Goat willow) in the species composition of the virgin forest resulted from the vitality deterioration of the Common beech and other tree species that formed the virgin forest earlier. These changes in the virgin forest cannot be explained by its internal dynamics, and the structural stability of the virgin forest indicates that these factors were due to external factors, first of all – changes of the site conditions (global warming). Therefore, our research gives grounds to consider some proposals for Climate-Smart Forestry in the beech forests of the Eastern Carpathians: for prevention of the wood volume losses due to natural disasters, it is necessary to pay more attention to damages to trees and crowns within cuts (stem hollows, stem cancer, big crowns); for the formation of a native forest stands through the natural regeneration it is expedient to reduce the size of gaps within cutting to 1 – 2 trees of the main layer; in order to save in forests those species, which tend to deteriorate vitality, it is necessary to prevent their damage within cutting; it is expedient to increase the intensity of cuttings by 15 % or reduce the intervals between them in order to regulate the wood volume because of the increase of increment. Keywords: site conditions change, uneven-aged forest stand, tree number, diameter increment, undergrowth, new species.