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ŠUMARSKI LIST 11-12/2021 str. 42     <-- 42 -->        PDF

Sessile oak (Quercus petraea (Matt.) Liebl.), together with pedunculate oak (Q. robur L.), is one of the most economically important deciduous forest tree species in Europe (Ducousso and Bordacs 2004, Eaton et al. 2016, Kesić et al., 2018). Their wood is of good quality and is valued for many purposes such as construction, as well as production of furniture and barrels. Also, oaks have an important ecological role because their acorns are a valuable food source for many animals. They are heliophilic, light-demanding trees which affect regeneration of many other tree species and enrich forest biodiversity. Although sessile oak prefers fertile and moist soils, it has a very large ecological niche and is quite tolerant of drought and poor soil (Ducousso and Bordacs 2004, Eaton et al. 2016). In the Republic of Serbia, the area under the forests of sessile oak occupies 173.200 ha and it makes up 7.9% of the total forest area (Banković et al. 2008). This species is widespread in Serbia and appears from Fruška gora and Vršačke planine in the north to Kozjak, Kozarnik and Metohija in the south, and from Mount Tara in the west to Stara Planina in the east. It occurs in lowlands (outside floodplains), in hilly and lower mountainous areas, and spreads from 200 m a. s. l., on the northern border of the area, to 1,200 m a. s. l., on the southern and eastern border of distribution in Serbia (Stojanović et al. 2007).
In most temperate and boreal forest ecosystems, the establishment, growth and survival of trees depend on association with ectomycorrhizal (ECM) fungi. ECM fungi successfully take water and nutrients from the soil and translocate them to plants from which they receive photosynthetically produced carbohydrates in return (Smith and Read, 2008). Mycorrhizas are one of the essential components of the forest ecosystem stability. Particularly, they have stabilizing effects on forest trees that are under environmental stress. Common mycelial networks have an especially important role in forest regeneration, succession, and resistance against different stress factors (Selosse et al. 2006). Such networks connect plants of the same or different species and can affect the physiological and ecological processes of plants (Selosse et al. 2006). Also, mycorrhizal mycelium connects forest trees and ground vegetation with decomposers in forest soil, which affects the sustainability, productivity, and vitality of the forest (Kraigher 1996). Moreover, mycorrhizal fungi can improve plant tolerance to abiotic stress factors such as heat, drought, or presence of heavy metals, as well as increase resistance to pathogens and boost plant immunity (Smith and Read 2008, Smith et al. 2010, French 2017). The functional compatibility of the symbionts in ectomycorrhiza is species-specific and depends on both partners while stress tolerance and adaptation of individual ectomycorrhizae on different environmental conditions depend on species of ECM fungus and its morphological, physiological and ecological characters (Kraigher 1996). Therefore, information on the ECM community structure can provide valuable information about the physiology of forest trees and the functioning of forest ecosystems (Kraigher et al. 2011).
Classification of ectomycorrhizae based on the exploration types (ETs) connects morphology of ECM fungi, especially the amount and differentiation of emanating elements, with their ecology (Agerer 2001). Contact ET is represented by ectomycorrhizae with a smooth mantle and without rhizomorphs. Short-distance ET is characterized by a voluminous cover of emanating hyphae but without rhizomorphs. Medium-distance ET can be divided into three subtypes. In fringe subtype the fungi often form fans of emanating hyphae and rhizomorphs, smooth subtype has rather smooth mantles with only a few emanating hyphae, while mat-forming fungi have only a limited range of exploration. Long-distance ET is characterized by smooth ectomycorrhizae with few but highly differentiated rhizomorphs (Agerer 2001).
Since data on the diversity of ECM fungi on oaks in the Republic of Serbia are scarce, especially those studied underground, the aim of this study was to make the first insight into the diversity of ECM fungi on sessile oak in Serbia by choosing two sessile oak stands situated in National Park Fruška gora.
Sampling site and procedures
Sampling was conducted in two sessile oak (Quercus petrea (Matt.) Liebl.) stands situated on the ridge of the mountain Fruška gora, at sites near Info center (N 45º 09’ 14.9”, E 19º 50’ 40.2 and 483 m a. s. l.) and near viewpoint Brankovac (N 45º 09’ 18.7”, E 19º 45’ 1.9 and 471 m a. s. l.). Other woody species present with a minor share were: Acer campestre L, Sambucus nigra L, Cornus sanguinea L, Fraxinus ornus L., Tilia argentea Desf. ex DC., and Rubus idaeus L at the site Info center; and Sambucus nigra L, Rubus idaeus L, Acer campestre L, and Tilia argentea Desf. ex DC at the site Brankovac.
Although Fruska gora spreads out in the zone with a moderate continental climate, the climate within the mountain area has subcontinental characteristics because of the change of the climatic characteristics along the height gradient and the forest cover. An exception is the climate of the mountain’s ridges, with cold winters and chilly summers. The lowest mean value of air temperature occurs in January and amounts - 0.6° C and the highest mean in July with 21.4° C, while the mean annual temperature is 11.2°C. According to the average monthly sum of precipitation in this area, the months with the most precipitations are May and June, while the driest are September and October. ( At the weather station Iriški venac for period 1965-1990 average