According to the Habitats Directive of the European Union, a favourable conservation status for the brown bear (Ursus arctos) should be targeted at the population level in large contiguous habitats such as the Alps, the largest mountain range in Europe. However, in most of the Alps brown bears are extinct and habitat suitability in these areas is often questionable. In our study, radio-racking data from four projects with 42 individual bears was compiled to assess habitat suitability. Discrete-choice models with random bear effects were fitted and compared to results obtained from compositional analysis and logistic regression. Sound definition of the available area in the discrete-choice model turned out to be essential. Brown bears showed a preference for forested and steep habitats and an avoidance of roads. Results from the three approaches were used to predict habitat suitability across the entire range of the Eastern Alps. Minimum potential population size was projected based on observed densities in Trentino and Central Austria, and ranged from 1228 to 1625 individuals, with 518 to 686 mature bears. This would satisfy a favourable conservation status. The developed methodology also has wide applicability to quantification of habitat suitability and potential population size in other cases where species are at risk.
COBISS.SI-ID: 3150502
For the first time a morphological variation of Juniperus oxycedrus L. subsp. oxycedrus in the whole Balkan Peninsula has been studied. Widely extended research included species populations from it's whole distribution range in this region; for a comparison also samples from disjunct range parts such as Serbia and Bosnia and Herzegovina were included. We revealed high phenotypic variation of the species within- as well as between populations. As expected, within population variation was higher. For the species J. oxycedrus a gender dimorphism of vegetative organs, mostly needles, has been proved for the first time. Studied populations showed no clear patterns of geographical differentiation. This may be a consequence of repeatedly occurring colonisation-retreat scenarios and suggests the existence of several small refugial populations. Results will be an important base for conservation management of a rare and marginal species, especially in Slovenia. Research is continued with a study of genetic variation of Juniperus oxycedrus populations as well as with a study of Arceuthobium oxycedri, semi-parasite woody species whose most important host is Juniperus oxycedrus.
COBISS.SI-ID: 3086502
Based on the spatial information system Silva-SI, we analysed for changes in the distribution of silver fir (Abies alba Mill.) in the period 1970-2008 using artificial neural networks (ANN), with respect to site, stand, and forest management variables. Most selected indicators confirmed the hypothesis of fir decline in the period 1970-2008, as evidenced by: i) reduced area of forests with a share of fir in the total growing stock ) 25% (from 18.9% to 9.5% of total area), ii) reduced share of fir in the growing stock of forest stands (from 17.5% to 7.5%), iii) ageing of the fir population, and iv) disproportionate share of fir saplings in total saplings relative to fir’s share in the growing stock of forest stands. A 1.5 % increase in fir distribution area in the observed period contradicts the decline hypothesis. ANN showed that spatiotemporal dynamics of fir was most affected by four variables: forest type, share of fir in potential natural vegetation, mean annual precipitation and mean annual temperature. The latter two, together with growing stock at the start of study period, connectedness of fir stands and bedrock, were significant predictors of decline of fir abundance in forest stands. Forest types represent a complex of site conditions and past forest management. The observed shift in fir distribution and changes in its abundance in the period 1970-2008 indicate impact of climate change.
COBISS.SI-ID: 3101606