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M. Cojzer, R. Brus: SPECIES COMPOSITION AND SUCCESSIONAL PATHWAYS ON ABANDONED ... Šumarski list br. 11–12, CXXXIV (2010), 581-591 hough its share decreased by almost a half. Sambucus nigra had a significant share among shrub species. Treatment F was in the pole stand phase. The tree species, whose share again increased a bit, still strongly prevailed over shrub species in this phase. The most abundant was Carpinus betulus. Among shrub species Corylus avellana had a significant share. The share of Fagus sylvatica, as the most numerous species in treatment D, strongly decreased with developmental phase aging, whereas the share of Carpinus betulus increased. On abandoned land as well as in forest the share of Carpinus betulus increased with developmental phase aging. 4 DISCUSSION – Rasprava The Haloze region has a similar trend of forest growth as Slovenia. Succession on abandoned agricultural land is influenced by numerous natural, socio-economic, infrastructural and accidental factors (Hočevar et al., 2004). The successinal process on farmland immediately starts after mowing or grazing is ceased, and in Haloze also after abandonment of vineyards and orchards. Vegetation on abandoned land develops through different stages (pioneer, middle and final stages), and proceeds in the direction of a late successional forest. Mature forest stage restoration is a long-term process that is connected with distinctive changes in species (Benabdellah et al., 2003). On the studied area Beech sites prevail, species composition changes through stages and is oriented toward beech associations ZGS, 2005a, 2005b). Only pioneer (early) stages were studied on abandoned land. 47 different species were recorded on abandoned land in the Haloze study area, of which 33 tree and 14 shrub species were found. A similar study was done in the Kočevje region (Mlinšek, 1968), where 38 species were recorded on fir-beech sites, of which 20 tree and 18 shrub species were found. If we compare the leading species, the most numerous shrub species on the Haloze hilly area is Cornus sanguinea, and among tree species Carpinus betulus prevails. In the Kočevje region the successive development inolves Corylus avellana, and among tree species Populus tremula prevails (Mlinšek, 1968). In Slovenia, as well as elsewhere in Europe and around the world, early stages on abandoned land involve different species. The succession of species immigration is different, depending mostly on the site and also on coincidence, and the immigration rate depends on the seed bank presence, soil state of preparation for germination and on the pioneer competition (Mlin šek, 1968). In the Pyrenees succession occurs with Pinus sylvestris (Pueyo and Begueria,2007), but on Slovenian karst it occurs with Pinus nigra (Eler, 2007). The results of other studies are hardly comparable with our findings, since most of the studies deal with successive changes of herbaceous species, which were not investigated in our case, and some other studies deal only with tree species without shrub species. In this study on abandoned land in Haloze, it was demonstrated that shrub species first appear, among which Cornus sanguinea is the most frequent. Shrub species represent an important ecological middle stage in forest development. In the next stage the share of shrub species decreases, and the share of tree species increases. At this developmental stage some economically significant tree species are already present. In the pole stand phase its structure and species composition are a bit more formed. At this stage tree species strongly prevail over shrub species, which have successfully completed their task and are slowly disappearing. On overgrowing land pioneer forest developed, by which site conditions are improved, since under its protection gradually other managed, shade tolerant and semi-shade tolerant species develop, and form managed forest. In later stages the share of economically significant species increases quickly (Mlinšek, 1968). It was found that in rejuvenated gaps of forest, Fagus sylvatica regenerates abundantly, which is otherwise a shade tolerant species. In very good conditions it germinates in abundance, but after a few years the number of individuals decreases quickly. This is accordance with the statement by Marinček (1987), who ascertained that elimination of individuals is particularly severe in the first few years and that the number of individuals slows down later. We discovered that its share almost halves in the thicket phase (Tab. 4), yet it still prevails over other tree species. In the pole stand phase the share of Fagus sylvatica diminishes again. In the race for territory Carpinus betulus won, and Quercus petraea is also competitive. The final vegetation stage is beech forest. It is thereby expected that the share of Fagus sylvatica will increase again in older developmental phases, and the share of Carpinus betulus will decrease. 5. CONCLUSION – Zaključak Abandoned land area in the Haloze region is increa-We also found that abandoned land is a bit more di- sing every year. It was found that forest area in the period verse than forest with regard to species composition. from 1985 to 2005 increased by 6.9 %, and it is expected Abandoned land differs from forest in the number of to increase by another 5.5 % in the next decade. shrub species, but it does not differ in the number of |