VIRGIN FORESTS AND FOREST RESERVES IN ... - Natura 2000
VIRGIN FORESTS AND FOREST RESERVES IN ... - Natura 2000
VIRGIN FORESTS AND FOREST RESERVES IN ... - Natura 2000
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78 Forest Reserves and their Research in Romania<br />
Mixed beech-coniferous natural forests<br />
The research recorded by PAPESCU-ZELET<strong>IN</strong> and PETRESEU in 1956, and DISSESCU in<br />
1964 (after VLAD, CHIRITA, DONITA and PETRESCU 1997) in spruce-beech-fir mixed<br />
forests shows no correlation between minimum - maximum age and diameter. Only the<br />
average age is positively correlated with diameter in range 30 - 65 cm. A beech can<br />
activate its growth even at the age of 130 - 140 years, and a fir at 100-150 years (e.g. a fir<br />
tree 465 years old had 6 cm diameter at the age of 90). The age of shrub-layer level varied<br />
between 20 - 120 years. The authors mentioned that due to ‘continuous feed-back<br />
processes’ this forest type maintained the initial structure. The regeneration in this type of<br />
mixture is possible only in open areas after old trees die. The ‘alternation of species’ in<br />
beech-fir mixtures in Semenic Mountains was described by BORLEA (1989). B<strong>AND</strong>IU<br />
(1977) explains this phenomenon as a result of differences in species radiation demands<br />
concerning light quality. The wood volume is high (600 - 1100 m 3 ), maximum tree-height<br />
is 50 - 60 m for fir and spruce, and 35 - 36 m for beech, and an average tree-height is<br />
40 m for fir, and 32 - 36 m for beech. The stability is very high.<br />
Beech natural forest<br />
In the Semenic mountains (6,000 ha) natural beech forests still exist. Some authors<br />
(RADULESCU 1937, TARZIU 1970, PAPAVA 1977) studied natural beech in Romania, and<br />
the main conclusions are: the diameter curve is similar to the theoretical curve for<br />
selective cuttings, there is no age-diameter correlation, and only average age-diameter<br />
correlation is significant and positive. There is a positive correlation between tree-height<br />
(interval 22 - 36 m) and diameter categories (from 39 - 62 cm). The fructification<br />
variability is very large, and fructification periodicity is from 3 - 4 years to 6 - 8 years,<br />
and strongly correlated with the altitude. The growth at the age of 200 years is similar to<br />
that of 80 - 100 years (PAPAVA 1977). The volume varies in range of 322 - 1195 m 3 , and<br />
the number of trees/ha is between 160 - 588. Stability is extremely high<br />
Oak natural forests and oak-mixed natural forests<br />
Oak natural forests were very much disturbed by anthropic activities. The oak-mixed<br />
natural forests have similar structure to that of the Bialoweza forests, with the exception<br />
of spruce (DONITA and PURCELEAN 1975, VLAD, CHIRITA, DONITA and PETRESCU 1997).<br />
The spatial structure consists of three levels: lower layer with hornbeam, intermediate<br />
layer with lime, cherry-tree, elm, sycamore maple, and superior layer with species of oak,<br />
ash, and sometimes elm or ash. The regeneration of oak is possible in these conditions<br />
(according to PASCOVSCHI 1967) due to their longevity (2 - 3 times higher than other<br />
species from this type of mixed forests).<br />
The comparison of natural forest and managed forest<br />
There were no systematic studies of comparing natural forests with the managed ones in<br />
Romania. Sporadically, different authors mentioned comparison of different qualitative or<br />
quantitative aspects, underlining the superiority of natural forest. There is only one<br />
exception: PAPAVA (1979) mentioned that the quality of wood is better in even-aged<br />
stands than in natural forests, and the absence of parasites is more obvious. This must be