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L. Kutnar, A. Kobler: PREDICTION OF FORESTVEGETATION SHIFT DUE TO DIFFERENT ... Šumarski list br. 3–4, CXXXV (2011), 113-126 DISCUSSION – Rasprava Simulations of the future climate with general circu lation models (GCMs) indicate an even more intensive climate change than that detected in the last decades of th the 20 century (Bergant2007). Most of the current climate projections for central Europe predict increased temperatures that are expected to cause an increase in the frequency and duration of intense summer droughts (e.g. IPCC 2001, 2007). Based on the three different climate scenarios, the simulations showed that the spatial pattern of forest vegetation types in Slovenia will be altered, and the vegetation type of major part of forest sites might be changed in the following decades under the impacts of climate change. Under warmer and wetter conditions, the vegetation shift might not be as drastic as under warmer and drier conditions. Nowadays, the most abundant and dominant tree species of the potential natural vegetation of central Europe is European beech (Fagussylvatica) (Ellenberg 1996); it is one of the ecologically and economically most important forest tree species presently supported by forest management in this area (Geßleretal. 2006). Beech forests of different types are prevailing in Slovenia too, occurring on calcareous as well as on silicate and mixed bedrock, on very different soil types, from hills (150 metres a.s.l.) to the subalpine belt (1650 metres a.s.l.) (Lesnik andMatijašić 2006,Dakskobler 2008). In Slovenia, approximately 63% of all forests currently grow on the beech, fir-beech and beech-oak potential sites; a reduction of beech sites is predicted to range between 7% (pessimistic scenario) and 42% (optimistic scenario) by the year 2070 (Kutnaret al. 2009).The beech forests are likely to be threatened, owing to beech sensitivity towards low water availability (Ellenberg 1996) and longer drought periods (Fotelli et al. 2002); the physiological performance, growth and competitive ability of European beech may be adversely affected by such changing climate conditions (Peuke et al. 2002, Geßler et al. 2006). In Slovenia, the situation may be aggravated by the fact that the area of distribution of beech forests includes many sites with shallow limestone- and dolomite- derived soils of low water storage capacity. By the end of century, the distribution range of fir is likely to change (Anićet al. 2009), and a decrease of the area of Dinaric fir-beech forests (Omphalodo-Fagetum) has been forecast in preliminary studies(Kutnar and Kobler 2007,Kutnar etal. 2009).According to the most pessimistic hot-and-dry scenario and assuming that the actual ecological niche of this vegetation type would not be changed in the future, this forest type might disappear completely from territory of Slovenia by the end of the 21stcentury. It seems that Dinaric fir- beech forests might be the most threatened forest com munity in Slovenia. Dinaric fir-beech forest is one of the most extensive forest communities in Slovenia (Dakskobler 2008), covering the Dinaric Mountain area, extended along theAdriatic coast over the Balkan Peninsula. In Slovenia, the Dinaric mountain chain reaches the south-easternAlps; in term of diversity, the vegetation on the border zones of different ecological influences is especially interesting. Beside their significant forest-management role, the Dinaric fir-beech forests are among the most important timber productive forests; their ecological and nature-conservation aspects are also significant. In area of these forests, the central part of habitat of three large European beasts of prey, the brown bear (Ursus arctosL.), lynx (Lynx lynxL.), and wolf (Canis lupus L.), and of many other species (Kutnar et al. 2002,Ódorand VanDoort2002) that are of special interest (e.g. Habitat Directive 1992), and the major part of these forests has been designated as part of the Natura 2000 network (Skoberne 2004). Thus, the loss of habitat of Dinaric fir-beech forests is likely to mean the potential extinction of many key species. Climate change has already caused numerous shifts in species abundance and distribution within the last 50 years (Parmesan and Yohe 2003) and it is presumed to be a major cause of species extinction in near future (Thomas etal. 2004). The share of different thermophile forests, which are less economically interesting and more fire-prone, will increase significantly, replacing the currently predominant mesic forests.The extension of thermophile forests all over the country would have very dramatic consequences and would affect forest-management, forest policy, and forest protection activities. The shift from dominant semi-natural mesic forests, mainly belonging to order ofFagetalia sylvaticae, to low density forests or woodlands, potentially belonging to orders of Quercetalia pubescentis,Erico-Pinetalia or even to Mediterranean evergreen forests and maquis shrublands of orderQuercetalia ilicis, is likely to happen by the end of the 21stcentury.The production of high-quality wood is one of the main objectives of forest management at present, but forests provide a wide range of other benefits. The future forest roles might be critically affected by redistribution and changed proportions among the forest types. Different types of thermophile forests of the sub- Mediterranean region of Slovenia have recently been damaged by forest fires (Mavsar etal. 2005,Jakša 2006). Driven by the warmer conditions and drought, similar as in the Mediterranean (Santos etal. 2002, Pausas 2004,Pereira etal. 2005,Moriondo et al. 2006), forest fire frequency and severity are very likely to increase in the future. |