Joint International Conference on Long-term Experiments ...

TREE GROWTH EQUATIONS IN DIFFERENT SITES FOR MIXED STANDS
OF SESSILE OAK WITH BEECH FROM THE MIDDLE BASIN OF THE
CRISUL REPEDE RIVER
Sorin Dorog
Faculty of Environmental Protection, University of Oradea
ABSTRACT
The determining of some growth equations, which comprise simultaneously increase
factors and diameters in relative values, is of interest because these can be used
afterwards for stands which are similar in structure and vegetate in the same
environmental conditions.
The paper presents three equations for three types of sites mostly encountered in
mixed stands of sessile oak with beech from the middle basin of the Crisul Repede
river. These equations are representative for the types of sites presented, their applying
in other areas of the country and eventually, in other types of sites, presents verrifyings
and ulterior adjustments of the mathematical pattern. The paper also presents the
intervals of the diameter categories for which these equations are viable..
Key words: equations, tree growth, mixed stands, beech, sessile oak.
1. INTRODUCTION
The dendrometrical characteristics of the even-aged stands present a larger or smaller
variability in relation with the species and the environmental conditions. The diameters
have according to the experts in this field variotion factors comprised between 20 – 30
%, this variability being caused by radial increases (Giurgiu V., 1967).
The stands formed by light demanding species are characterised by high
correlation coefficients compared to shade and half – shade demanding species (Leahu
I., 1994). Relatively even – aged stands have a decrease of the radial growth rythm for
the superior diametre categories (Giurgiu V., 1979). In such circumstances there is a
difference between radial growth average on each stand and the radial growth of the
medium diameter category.
The liniarity after which the variation of the radial growth can be ajusted in relation
with the diameters at even – aged stands, was demonstrated an emphasized by the F test.
The determining of some growth equations, which can comprise at the same time
growth factors and diameters in relative values, shows interest because of the easy way
with which these can be used afterwards at stands, which are not only structurally
similar, but also having similar environmental conditions (Cook E., 1985).
Once these equations have been established, they provide the users accurate results
concerning the growth and samples are taken with the boring bit from the medium
category of diameters (Cook E., 1990).
This paper was based upon the analysis of mixed even – aged and relatively even –
aged stands of sessile oak and beech, in three types of sites, representative with regards
to the offered conditions and percentage surface. In the studied stands trial squares of
2500 m 2 were placed and in these places all the trees were inventoried, starting with the
8 cm diameter. For the medium diameter tree category, samples were taken with the
Pressler’ s borer (Dorog S., 2006).
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