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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

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