Although sessile oak is one of the most important deciduous forest tree species in Europe, data on the diversity of ectomycorrhizal (ECM) fungi on sessile oaks in the Republic of Serbia are scarce. The aim of this study was to provide the first insight into the diversity of ECM fungi on sessile oak in Serbia. Two sites Info center and Brankovac, located in National Park Fruška gora were chosen. ECM fungi were identified combining morphological and anatomical characterization with molecular analysis of nuclear rDNA internal transcribed spacer (ITS) region. All vital ECM root tips were counted, diversity indices were calculated, and ECM fungi were classified into the exploration types. The granulometric and chemical composition of soil were analyzed as well. At both sites, 26 different ECM fungal taxa were recorded in total, 17 taxa were observed at the site Info center and 12 taxa at Brankovac. ECM communities consisted of a few abundant taxa and a larger number of rare taxa. Lactarius quietus, Cenococcum geophilum, and Tomentella sublilacina were recorded at both sites. High abundance of contact and short-distance exploration types recorded in studied stands suggests that soils are sufficiently rich in total nitrogen and organic matter. Values of diversity indices recorded in studied sessile oak stands from Fruška gora were lower in comparison to those obtained in stands of different oak species across Europe which is likely induced by drought. To get a more thorough insight into the diversity of ECM fungi on sessile oak, research should be continued at more sites and seasonal dynamics should be included.

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.

The physiological and biochemical responses of pedunculate oaks (Quercus robur L.) to heat stress (HS) and mycorrhization (individually as well in combination) were estimated. One-year-old Q. robur seedlings were grown under controlled conditions in a pot experiment, inoculated with a commercial inoculum of ectomycorrhizal (ECM) fungi, and subjected to 72 h of heat stress (40 °C/30 °C day/night temperature, relative humidity 80%, photoperiod 16/8 h) in a climate chamber, and they were compared with seedlings that were grown at room temperature (RT). An in-depth analysis of certain well-known stress-related metrics such as proline, total phenolics, FRAP, ABTS, non-protein thiols, and lipid peroxidation revealed that mycorrhized oak seedlings were more resistant to heat stress (HS) than non-mycorrhized oaks. Additionally, levels of specific polyamines, total phenolics, flavonoids, and condensed tannins as well as osmotica (proline and glycine betaine) content were measured and compared between four treatments: plants inoculated with ectomycorrhizal fungi exposed to heat stress (ECM-HS) and those grown only at RT (ECM-RT) versus non-mycorrhized controls exposed to heat stress (NM-HS) and those grown only at room temperature (NM-RT). In ectomycorrhiza inoculated oak seedlings, heat stress led to not only a rise in proline, total phenols, FRAP, ABTS, non-protein thiols, and lipid peroxidation but a notable decrease in glycine betaine and flavonoids. Amounts of three main polyamines (putrescine, spermine, and spermidine) were quantified by using high-performance liquid chromatography coupled with fluorescent detection (HPLC/FLD) after derivatization with dansyl-chloride. Heat stress significantly increased putrescine levels in non-mycorrhized oak seedlings but had no effect on spermidine or spermine levels, whereas heat stress significantly increased all inspected polyamine levels in oak seedlings inoculated with ectomycorrhizal inoculum. Spermidine (SPD) and spermine (SPM) contents were significantly higher in ECM-inoculated plants during heat stress (approximately 940 and 630 nmol g−1 DW, respectively), whereas these compounds were present in smaller amounts in non-mycorrhized oak seedlings (between 510 and 550 nmol g−1 DW for Spd and between 350 and 450 nmol g−1 DW for Spm). These findings supported the priming and biofertilizer roles of ectomycorrhizal fungi in the mitigation of heat stress in pedunculate oaks by modification of polyamines, phenolics, and osmotica content.

The ongoing climate change have multi-faceted effects not only on metabolism of plants, but also on the soil properties and mycorrhizal fungal community. Under climate change the stability of the entire forest ecosystems and the carbon balance depend to a large degree on the interactions between trees and mycorrhizal fungi. The main drivers of climate change are CO₂ enrichment, temperature rise, altered precipitation patterns, increased N deposition, soil acidification and pollutants, ecosystem fragmentation and habitat loss, and biotic invasion. These drivers can impact mycorrhizal community directly and indirectly. We discussed the influence of each driver on mycorrhizal community and outlined how mycorrhizas play an important role in the resilience and recovery of forest ecosystems under climate change, by mitigating detrimental effects of CO₂ enrichment, temperature rise, drought, lack of nutrients, soil acidification, pollutants, pests, and diseases. Conservation of the overall biodiversity in forest ecosystems as well as providing the most favourable conditions for the development of mycorrhizae can contribute to increasing the resilience of forest ecosystems to climate change.

This study presents investigation of sessile oak cynipid gall wasps fauna of Mt Fruška Gora. Gall wasps are insects, from the family Cynipidae, that induces galls mainly on oaks. Complex of sessile oak cynipid gall wasps were investigated during 4-year period (2016 - 2019). The survey was carried out on five sites: Kraljeve stolice, Spomenik, Brankovac, Ležimir and Rohalj baze. At total, number of seventeen cynipid gall wasps species were identified: Andricus aries (Girauld, 1859), Andricus caliciformis (Giraud, 1859), Andricus coriarius (Hartig, 1843), Andricus curvator (Hartig, 1840), Andricus dentimitratus (Rejto, 1887), Andricus glutinosus (Giraud, 1859), Andricus kollari (Hartig, 1843), Andricus lignicolus (Hartig,1840), Andricus lucidus (Hartig, 1843), Andricus solitarius (Fonscolombe, 1832), Cynips quercusfolii (Linnaeus, 1758), Cynips quercus (Fourcroy, 1785), Biorhiza pallida (Oliver, 1791), Neuroterus albipes (Schenck, 1863), Neuroterus anthracinus (Curtis, 1838), Neuroterus numismalis (Fourcroy, 1785) and Neuroterus quercusbaccarum (Linnaeus, 1758). Gall wasp A. dentimitratus is first record for Serbia. The most frequent species were A. lignicolus and A. glutinosus, which were found on all five observed sites.