engleski

Effects of stand structure on regeneration dynamics of mixed uneven-aged forest

Uneven-aged fir and beech forests today are usually characterized by disturbed and frequently unstable uneven-aged structure. Some of the problems in managing such stands, as well as causes of disturbances, are: absence of natural fir regeneration, large shifts from optimal stand volume, volume increment decrease, physiological weakening and die-back of dominant trees, negative impacts of climate change (warming, drought and acid rain). To gain an insight into the dynamics of such stands, a permanent experimental plot of 1 ha in size was established in 1998. All trees with diameter at breast height (DBH) over 8 cm were stem-mapped and numbered. DBH, total tree heights and crown base heights of all trees were measured and detailed map of crown projection areas was made. Structure and abundance of regeneration was measured on sub sample of 360 m2 in size and plants were classified into height-age classes. The plot was remeasured in 2003 and 2007. Crown projection maps were digitized and processed in ESRI Arc Map software package, and three-dimensional stand visualization model was made. According to the results of this research, there is a considerable decrease in the number of young fir plants. None of the remaining fir plants measured over 30 cm in height. Young beech plants are greater in numbers, but of very low quality. Fir is non-existent in lower classes of diameter distribution, which implicates very poor fir recruitment during the last few decades. Instead of fir, young beech plants are filling in the lower diameter classes. The specific vertical profile of mixed fir and beech uneven-aged forest stand is also disturbed. The results of this research indicate the questionability of satisfying natural regeneration as a basic condition for the structural stability of these stands.

uneven-aged forest; beech; fir; natural regeneration; stand structure

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