In light of climate change, pedunculate oak (Q. robur L.) was marked as the most threatened European tree species. Pedunculate oak is particularly jeopardized by powdery mildew disease caused by Erysiphe alphitoides. We hypothesized that priming of this tree species with ectomycorrhizal fungi could mitigate biotic stress and produce bioprotective properties against the disease. In this study, we have compared oaks’ foliar physiological and biochemical responses upon infection with E. alphitoides in the presence and absence of ectomycorrhizal fungi (ECM). The main aim of this study was to inspect how ECM modulate an oak’s biochemical response to infection with E. alphitoides, particularly at the level of the accumulation of the main polyamines (putrescine, spermidine, and spermine), soluble osmolytes (proline and glycine betaine), and phenolics (total phenolic content, flavonoids, and condensed tannins). A polyamine quantification was performed after derivatization by using high-performance liquid chromatography (HLPC) coupled with fluorescent detection. Oak seedlings inoculated with ECM fungi exhibited significantly higher levels of putrescine, spermine, and proline compared to non-inoculated seedlings, indicating the priming properties of the ECM. E. alphitoides caused an increase in individual and total polyamine content and lipid peroxidation in oak leaves regardless of the effect of ECM, while causing a decrease in physiological and antioxidative parameters and water use efficiency (WUE). Common biochemical parameters may contribute to understanding the underpinning plant defense mechanisms in three-way interactions among plants and pathogenic and ectomycorrhizal fungi and can be used as reliable adaptability descriptors in the context of climate change.

The general aim of this work was to compare the leaf-level responses of different protective components to water deficit and high temperatures in Quercus cerris L. and Quercus robur L. Several biochemical components of the osmotic adjustment and antioxidant system were investigated together with changes in hormones. Q. cerris and Q. robur seedlings responded to water deficit and high temperatures by: (1) activating a different pattern of osmoregulation and antioxidant mechanisms depending on the species and on the nature of the stress; (2) upregulating the synthesis of a newly-explored osmoprotectant, dimethylsulphoniopropionate (DMSP); (3) trading-off between metabolites; and (4) modulating hormone levels. Under water deficit, Q. cerris had a higher antioxidant capacity compared to Q. robur, which showed a lower investment in the antioxidant system. In both species, exposure to high temperatures induced a strong osmoregulation capacity that appeared largely conferred by DMSP in Q. cerris and by glycine betaine in Q. robur. Collectively, the more stress-responsive compounds in each species were those present at a significant basal level in non-stress conditions. Our results were discussed in terms of pre-adaptation and stress-induced metabolic patterns as related to species-specific stress tolerance features.

The prioritization of alien species according to the magnitude of their environmental impacts has become increasingly important for the management of invasive alien species. In this study, we applied the Environmental Impact Classification of Alien Taxa (EICAT) to classify alien taxa from three different taxonomic groups to facilitate the prioritisation of management actions for the threatened riparian forests of the Mura-Drava-Danube Biosphere Reserve, South East Europe. With local experts we collated a list of 198 alien species (115 plants, 45 insects, and 38 fungi) with populations reported in southeast European forest ecosystems and included them in the EICAT. We found impact reports for 114 species. Eleven of these species caused local extinctions of a native species, 35 led to a population decrease, 51 to a reduction in performance in at least one native species and for 17 alien species no effects on individual fitness of native species were detected. Fungi had significantly highest impact and were more likely to have information on their impacts reported. Competition and parasitism were the most important impact mechanisms of alien species. This study is, to our knowledge, the first application of EICAT to all known alien species of several taxonomic groups in a protected area. The impact rankings enabled to identify taxa that generally cause high impacts and to prioritize species for the management in protected areas according to their impact magnitudes. By following a standardized impact protocol, we identified several alien species causing high impacts that do not appear on any expert-based risk list, which are relevant for policymakers. Thus, we recommend that alien species be systematically screened to identify knowledge gaps and prioritize their management with respect to spatio-temporal trends in impact magnitudes.

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.

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In the paper, the structural, production and development characteristics of a potentially overripe and devitalized sessile oak stand on Fruška Gora were investigated. Structural and production characteristics were investigated on the ICP Forests plot Level 2, where data from two surveys in 2015 and 2020 were used. Developmental characteristics were investigated using center cores of 22 dominant sessile oak trees sampled in 2014 and using electronic and manual dendrometers on six trees from 2015 Topola/Poplar 2022, 210, 29-40 www.ilfe.org 30 to 2022. The diameter distribution shows that the researched stand is two-storeyed and mixed, and based on the diameter distribution of the first floor, it was a pure even-aged stand of sessile oak in the past. Productivity in the period from 2015 to 2020 shows stagnation, but with a clear decrease in the share of sessile oak, especially in the total basal area and volume. By analyzing the age and development characteristics, individual trees show clear signs of devitalization during most of their life, and for the whole stand we can conclude that it is significantly too old and in clear devitalization, especially after 2019. The diameter growth in the growing season is characterized by small values and predominantly occurs in May and June. The general conclusion is that the researched stand is overaged, devitalized (the main species of the stand is the sessile oak), with the regression of the sessile oak in relation to other competing species and very slow growth dynamics even on an annual basis, which from the perspective of future management puts the forestry profession in a very unenviable role and requires an adaptive approach to managing such stands.

It is considered that different plant organic compounds, known as phytoncides are creditable for positive effects of Forest therapy on human health. Ongoing pandemic has also put these compounds in research focus considering potential use for novel corona virus treatment. This research was conducted in order to examine the potential of Tilia cordata Mill. considering volatile organic compounds (VOCs) content for the use in Forest therapy. In order to determine qualitative and quantitative content of phytoncides, as well the variability among genotypes growing in the same environmental conditions, leaf samples from genotypes of T. cordata were collected from the Fruška gora (Serbia) during 2019. VOCs determined in fresh herbal material were analyzed by HeadspaceGC/MS and VOCs determined in essential oil were obtained by GC/MS. The results showed the presence of 17 different phytoncides (monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes, aliphatic compounds and diterpenes) in all tested genotypes. According to the mean values of the obtained results, the most abundant classes of phytoncides among the examined genotypes were monoterpene hydrocarbons (87.05), followed by aliphatic compounds (36.59) and oxygenated sesquiterpenes (34.60). The highest coefficient of variation (CV) among phytoncide content in tested T. cordata genotypes has been observed within oxygenated monoterpenes (43.12%), sesquiterpene hydrocarbons (28.18%), and diterpenes (27.04%). Some individual monoterpene hydrocarbons, such as o-cymene (19.92%) and a-pinene (17.40%) had the highest CV in terms of its presence in analyzed genotypes. In addition, the principal component analysis (PCA) showed more notable clustering within the VOCs determined in essential oil in comparison to VOCs determined in fresh herbal material. Considering the phytoncide content detected in T. cordata leaves, this species has high potential for the use in human health improvement within Forest therapy.