In the present paper we studied the genetic diversity and genetic structure of five Norway spruce (Picea abies (L.) Karsten) natural populations situated in Serbia, belonging to the southern lineage of the species at the southern margin of the species distribution range. Four populations occur as disjunct populations on the outskirts of the Dinaric Alps mountain chain, whereas one is located at the edge of Balkan Mountain range and, therefore, can be considered as ecologically marginal due to drier climatic conditions occurring in this region. Due to the negative effect of biotic and abiotic stress factors, the sustainability of these populations is endangered, making conservation of their genetic resources one of the key measures of Norway spruce persistence in Serbia under climatic changes. The insight on genetic diversity and genetic structure of the studied spruce populations can provide the information required for the initiation of programs aimed at the conservation and utilization of spruce genetic resources at the rear edge of species environmental limits. Norway spruce genetic variation and population genetic structure were estimated using eight EST-SSR markers. The results showed that mean expected heterozygosity was 0.616 and allelic richness 10.22. Genetic differentiation among populations was low (F_st = 0.007). No recent bottleneck effect or isolation by distance were detected. Bayesian clustering, obtained with STRUCTURE, grouped the populations into two genetic clusters, whereas UPGMA analysis distinguished three main groups approximately in line with the geographic area of occurrence. Based on the study results and the EUFORGEN Pan-European strategy for genetic conservation of forest trees, the establishment of additional dynamic gene conservation units must be considered in Serbia in order to protect the adaptive and neutral genetic diversity of the species.

U radu se prikazuju rezultati usporedbe strukturnih i proizvodnih karakteristika bukovih sastojina gospodarskog i prašumskog tipa u Srbiji. Istraživano je pet sastojina gospodarskog i tri sastojine prašumskog tipa. Cilj ovog istraži­va­nja bio je utvrditi utjecaj prethodnog gospodarenja šumama na strukturnu raznolikost i proizvodne osobine visokih bukovih šuma u Srbiji. Istraživane sastojine nalaze se u planinskom rasponu od 400 do 1200 metara nadmorske visine u područjima gdje se nalaze najproduktivnije bukove šume u Srbiji (slika 1 i tablica 1). Strukturne karakteristike uspore­đe­ne su pomoću sljedećih parametara: visinske krivulje, debljinska struktura, Gini indeks, koeficijent varijacije, koeficijent vitkosti i maksimalne dimenzije dubećih živih i mrtvih stabla. Sastojinsku gustoću i produktivne osobine proučavane su pomoću sljedećih procijenenih taksacijskih elemenata: broj stabala, temeljnica, volumen, biomasa, zaliha ugljika, srednji promjer po temeljnici, Lorajeva srednja visina i volumen mrtvog drveta. Najveće razlike pronađene su u dimenzijama najvećih stabala u bukovim sasatojinama gospodarskog i prašumskog tipa (tablica 4). Određene razlike pro­na­đene su u obliku visinskih krivulja i debljinskoj strukturi, i vrijednostima koeficijenta vitkosti (slike 2, 3, 4 i 5, i tablica 3). Međutim, Ginijev indeks i koeficijent varijacije pokazuju da su bukove sastojine gospodarskog tipa u Srbiji u velikoj mjeri sačuvale iskonsku strukturnu raznolikost (tablica 2 i slika 6). Razlike u prosječnim vrijednostima taksacijskih elemenata sastojina gospodarskog tipa visokih bukovih šumama u Srbiji u odnosu na sastojine prašumskog tipa su statistički značajne, što nam govori da je prethodno gospodarenje imalo značajan utjecaj na promjene u proizvodnim karakteristikama ovih šuma u Srbiji (tablica 5).

The Norway spruce is one of the most important tree species in Europe. This tree species has been put under considerable pressure due to the ongoing impacts of climate change. Meanwhile, frequent droughts and pest outbreaks are reported as the main reason for its dieback, resulting in severe forest cover loss. Such was the case with Norway spruce forests within the Kopaonik National Park (NP) in Serbia. This study aims to quantify, spatially and temporally, forest cover loss and to evaluate the sensitivity of various vegetation indices (VIs) in detecting drought-induced response and predicting the dieback of Norway spruce due to long-lasting drought effects in the Kopaonik NP. For this purpose, we downloaded and processed a large number of Landsat 7 (ETM+), Landsat 8 (OLI), and Sentinel 2 (MSI) satellite imagery acquired from 2009 to 2022. Our results revealed that forest cover loss was mainly driven by severe drought in 2011 and 2012, which was later significantly influenced by bark beetle outbreaks. Furthermore, various VIs proved to be very useful in monitoring and predicting forest health status. In summary, the drought-induced response detected using various VIs provides valuable insights into the dynamics of forest cover change, with implications for monitoring and conservation efforts of Norway spruce forests in the Kopaonik NP.

European beech (Fagus sylvatica L.) is the most important deciduous tree species in Europe. According to different climate scenarios, there is a relatively high probability of a massive decline in and loss of beech forests in southern Europe and in the southern part of central Europe. Thus, the authors of this study explored the dynamics of tree diameter increments and the influence of extremely dry years on the width of tree rings. This study used dendroecological methods to analyze the growth and diameter increments of European beech trees at locations in Serbia and the Republic of Srpska. The sampling was conducted along the vertical distribution of beech forests, at five sites at the lower limit of the distribution, at five optimal sites of the distribution, and at five sites at the upper limit of the distribution. Long-term analyses indicate that dry conditions during a growing season can reduce tree-ring width, but a reduction in tree growth can be expected as a result of more than one season of unfavorable conditions. Low temperatures in autumn and winter and prolonged winters can strongly affect upcoming vegetation and reduce tree development even under normal thermal conditions during a growing season.