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Extreme weather conditions, namely droughts, heat waves, heavy rains, floods, and landslides are becoming more frequent globally and in Serbia as a result of climate change. Generally, various parts of human society are affected by changing climate conditions. Forest ecosystems are one of the most sensitive systems to weather and climate. In that sense, small changes may lead to large disturbances including forest decline, outbreaks of insect pests and diseases and eventually mortality. In Serbia, the average temperature in forest ecosystems of the most important and abundant forest tree species has risen for more than 1°C in the last thirty years (1990-2019) in comparison to the previous period (1961-1990). During the last thirty years, the northern and western parts of Serbia experienced an increase in precipitation as opposed to the southern and eastern parts of the country. If one takes a closer look at the climate within a particular forest stands, it would seem that the effect of precipitation decrease is stronger in less humid parts of a tree species range. In this paper, we discuss various aspects of climate change impacts on forests and forestry, including forest ecology, genetics, physiology, pests and diseases, ground vegetation, monitoring, reporting and verification system, climate change litigation and perspectives of forests in the 21st century in Serbia.

Quercus robur L. is one of the most valued tree species of deciduous temperate forests. However, in the last decade, serious oak declines and loss of adaptation plasticity have been reported throughout Europe as a consequence of drought. Therefore, the aim of the present study was to define the adaptation potential of five Q. robur half-sib lines from the UNESCO Biosphere Reserve Mura-Drava-Danube to drought, using physiological, anatomical and biometrical traits. Half-sib lines that exhibited drought tolerance had particular suites of trait expression regarding biometrical traits (seedling height, root length, root to shoot ratio of dry mass and specific leaf area), leaf stomatal traits (stomatal density per mm2, stomata guard cell length and width, stomatal aperture length and width) and leaf structural traits (adaxial epidermis thickness, palisade parenchyma thickness, spongy parenchyma thickness, lamina thickness). All of the observed parameters of chlorophyll a fluorescence were shown to be good indicators of short-term and severe drought. For the selection of drought-tolerant half-sib lines, all studied chlorophyll a fluorescence parameters associated with the heat dissipation of light energy (coefficient of non-photochemical quenching, quantum yield of regulated energy dissipation, Stern-Volmer type non-photochemical fluorescence quenching) and one parameter related to photochemical dissipation of light energy (effective quantum yield (efficiency) of PS II photochemistry) were proven to be suitable. On the other hand, the coefficient of photochemical quenching, coefficient of photochemical fluorescence quenching assuming interconnected photosystem II antennae and electron transport rate were not suitable for distinguishing the different responses of the studied half-sib lines under drought. The importance of results of the present study is in the selection of drought-tolerant Q. robur half-sib lines for future reforestation programs, particularly in protected areas with sensitive forest management and restricted activities for mitigation of the adverse effects of climate changes.

In the present study, variations of leaf stomatal traits for fourteen European beech provenances (Fagus sylvatica L.), originating from six countries (Bosnia and Herzegovina, Croatia, Germany, Hungary, Romania and Serbia), were evaluated at the inter-and intra-provenances levels. Ten stomatal traits (stomatal density (SD), guard cell length (LA) and width (WB), stomatal aperture length (La) and width (Wb), pore surface of guard cell (SPSLAWB), pore surface of a widely opened pore (SPSLaWb), coefficient (SSC), potential conductance index (PCI) and relative stomatal pore surface (RSPS)) were examined using methods of univariate (ANOVA and Tukey's HSD test) and multivariate statistical analyses (principal component analysis (PCA), discriminant analysis and cluster analysis). The results obtained provide significant insight into the genetic diversity and differentiation of European beech provenances and confirmed high genetic variability within and between examined European beech provenances, according to all examined parameters. Differences at the intra-provenance level had a bigger impact on most of the 938

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Understanding intraspecific genetic variation is one of the principal requirements for the evaluation of tree species capacity to cope with intensive climatic changes, as well as designing long-term conservation programs. Herein, we evaluated the genetic diversity and genetic structure of seven pedunculate oak (Quercus robur L.) populations, located at the southern margin of its distribution range on the Balkan Peninsula (Serbia). The objective of the study was to propose future in situ conservation measures aimed at protection of pedunculate oak adaptive and neutral genetic diversity at the species rear-edge. Genetic diversity and structure were estimated using twelve highly polymorphic simple sequence repeat (SSR) markers. The mean expected heterozygosity (He) was 0.769, allelic richness (AR) 9.63, and private allelic richness (pAR) 0.79, indicating high genetic diversity in the studied populations. Genetic differentiation among the populations was low (Fst = 0.032). Structure analysis, the unweighted pair group method with arithmetic mean (UPGMA) showed the existence of two gene pools unrelated to the populations’ area of occurrence. Taking into consideration the results of the current study and previous conservation activities on the pedunculate oak in Serbia, as well as the importance of rear-edge populations in the long-term conservation of the species genetic diversity, we suggested establishing three additional gene conservation units for securing long-term sustainability of the species.

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