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ŠUMARSKI LIST 3-4/2013 str. 10     <-- 10 -->        PDF

Natural forests are extremely rare in Europe, especially if the European part of Russia is not taken into account (Par­viainen et al. 2000). However, they are particularly important for the development of basic and applied natural sciences (Peterken 1996). The idea of the total forest reserves was initiated by foresters to ensure old-growth forests for the future and thus references for managed forests on different sites (Leibundgut 1957). At present, forest reserves are considered to be even more important due to the rising importance of ecosystem services, environmental monitoring, and nature protection (Parviainen et al. 2000). In the 1970s a network of forest reserves was established in Slovenia (Mlinšek et al. 1980). This network has been successfully maintained, although it was altered slightly due to the re-privatization of forests in the 1990s. Today there are 172 forest reserves in Slovenia covering 9,792 ha, which is less than 1 % of the total forest area in Slovenia (Diaci et al. 2006). A damaged, or artificially made forests for example plantations; areas damaged by fire and wind; and spontaneously developed forests on former agricultural land. One important goal for research in such reserves is to gain an understanding of secondary succession and recovery processes which have not experienced human intervention.
Succession refers to the sequence of changes in vegetation that occurs after a site is disturbed – a sequence of events that normally leads to the re-establishment of the vegetation that was initially removed. If the disturbance is minor, and the soil and propagules remain, as in the case of pasture land surrounded by woods, the recovery of the vegetation towards the forest is usually rapid; this is termed secondary succession (Keddy, 2007).
Forest sites on which silver fir dominates (Abies Alba Mill.; thereafter fir) are underrepresented in the Slovenian forest reserve network (Marinšek and Diaci 2011) since most of these ecosystems are very productive and yield high income. However, due to the overall importance of fir in Southeast Europe and the many insufficiently explained processes related to fir such as fir decline, overbrowsing, reciprocal replacement, coexistence with other species, and climate change (Šafar 1951, Matić et al. 2001, Tikvić 2008, Anić et al. 2009, Diaci et al. 2010, 2011), knowledge on developmental dynamics from reserves is a prerequisite for the improvement of fir conservation management.
The "Lipje" forest reserve is considered special for several reasons. Here, an almost pure fir stand grows in an unusual combination of site factors, i.e., very low altitude (370–380 m), carbonate parent material, and a geographic location in the southern part of Slovenia. Moreover, there is some indication that the stand originated from the spontaneous expansion of forest on former pastures, where fir may have played the role of the initial species in secondary succession. However, systematic research in the reserve has not yet been undertaken.
Fir is regarded as a late climax species that is very efficient in its overall resource use and thus extremely shade tolerant (Ellenberg 1988). In Slovenia most fir-dominated stands grow on deep, heavy, fresh neutrophilic or acidophilic soils of the submontane and montane vegetation belt (Galio rotundifolii-Abietetum M. Wraber 1959, Bazzanio-Abietetum M. Wraber 1958; Dakskobler and Marinšek 2009). However, there are also localized fir ecosystems that overgrow very rocky calcareous or silicate parent material (e.g. Calamagrostio-Abietetum Horvat (1950) 1962, Paraleucobryo-Abietetum Belec et al. ex Belec 2009, Neckero-Abietetum Tregubov 1962). In Croatia a forest association is reported (Vukelić et al. 2006) where fir grows on limestone at an elevation between 700–800 m a.s.l. in extremely thermophilic habitat (Ostryo-Abietetum (Fukarek 1963) Trinajstić 1983).
Fir is reported to be susceptible to human disturbances such as forest fires, heavy logging, and forest grazing (Kozakova