VIRGIN FORESTS AND FOREST RESERVES IN ... - Natura 2000

COST Action E4: Forest Reserves Research Network • • Proceedings of the Invited Lecturers' Reports ⁄ p. 95 - 110
STAND DYNAMICS OF THE VIRGIN FOREST RAJHENAVSKI
ROG (SLOVENIA) DURING THE PAST CENTURY
ABSTRACT
by Andrej BONČINA*
The paper concerns developmental features of the virgin forest Rajhenavski Rog forest
stands during the past hundred years. The study is based on the first data on forests from
1893, full callipering of forest stands in the period 1957-1995, stand inventories carried
out in selected permanent sample plots, and maps of horizontal structure of the virgin
forest made in 1985 and in 1995. The contention about the alternation of dominant tree
species, silver fir and European beech, was confirmed. The proportion of silver fir in the
growing stock was the lowest in 1893 (27%) and the highest in 1967 (61%). It fell to 57%
by 1995, and all indices suggest a further decrease in the future. During the period
analysed, d.b.h. structure of forest stands changed as well. This shows that the virgin
forest is not a static system, although the growing stock remained practically unaltered
during this period (800m 3 /ha). An analysis of changes in the horizontal structure of virgin
forest stands over a decade shows that the proportion of the optimal stage was decreasing
while the proportion of the terminal and juvenile stage was increasing. Developmental
dynamics of individual stands depends on tree species composition.
INTRODUCTION
Virgin forest relicts are of many-sided significance. They are perfect for studying the
natural structure of a forest and its processes. The main questions related to such a study
are: How does a virgin forest function? How it is preserved although it is subject to
changes? Which are the important organisational principles? Permanent sample plots and
stand inventories conducted over a longer period of time give us an insight into
developmental processes. Virgin forest relicts are systems which are relatively more
closed and less disturbed than managed forests. Nonetheless, they too are affected by
atmospheric pollution, populations of big herbivores, tourism and other factors. Areas
they occupy are definitely not large enough for a ‘pre-biocoenosis’ of animal and plant
species to be established, therefore they are better referred to as virgin forest relicts.
* Doc. Dr. A.B., Department of Forestry and Renewable Forest Resources, Biotechnical Faculty, University of
Ljubljana, PO Box 2995, 1001 Ljubljana, Slovenia