Forest vegetation
Forest vegetation contains various hydrophilic forests of European ash, poplar, willow and black alder. On alluvial parts there are communities of oak and hornbeam (Genisto elatae-Quercetum Horv. 1938 subass. Carpinetosum betuli Vuk. 1958) as well as lime tree, English oak and cerris (Rusco aculeate-Tilio-Querce-tum Erd.1955.-Erdeshi,ae.al 2001). The total area under the forest in the Reserve is 16,74%.Growing of willow and Euro-american poplar on the area of 110ha owned by the Forestry of Sremska Mitrovica started on the farmland of Vrbovac in 1962. The remains of logs in mud indicate that oaks existed along the Zasavica. During walking through the forest we can pass by English oak (Quercus robur L), cerris (Quercus cerris L), European ash (Fraxinus angustifolia L), elm (Ulmus effuse L) and wild pear (Pirus pirastri L). In the area near the river banks there is black alder (Alnus glutinosa L) which has small knots on its root containing bacteria capable of binding free nitrogen. From bushy species in the oak and European ash forests we can find hazel tree (Corylus avellana L), spindle tree (Evonimus europeus L) and Rhamus cathartica L. In the early spring there are Amemona ranunculiodes L, Corydalis cava Vent, Covallaria majalis L and Scilia bifolia L with its azure blue flower but they are soon replaced by Physalis alkekengii L., Clematis integrifolia L.,and Arum maculatum L.
In the remaining fragments of oak forests there had been found a single orchid as well as one related species. Belonging to the Family Orchidaceae – original orchid on count is the species: Cephalanthera alba (Cr.) Smk 1886 – This is a perenial plant, grows up to 60 cm in height, with slanted protruding chainlike leaves. The flower consists of 20 small white flowers that appear from the month of May to August. It belongs to the Middle European species. According to the list of flora in Serbia (1986) up to now, this species has been found in habitats on Fruska Gora and according to the flora of the District of Srem (1991) it populates luznjak oak forests and linden tree forests. The areal of this species is Eurasia with its eastern borders reaching the Ural Mountains, the Caucasus and as far as Siberia. This orchid has a broken down areal, for it is a rare plant at Fruska Gora and it has a differentiated character belonging to the flora of its western region where it is found in a phase of dying out spontaneously.
It is morphologically similar to genuine orchids and the species that has been recorded at Zasavica is Orobanche luteum L. – purple water orchid. This genus incorporates a larger number of non-chlorophyll parasitic species, which develop and grow on the roots of many plants. The plant grows to a height of 60 cm, the stem does not branch out and is purple or violet in color and is flour-like and hairy. The ear is cylindrical in shape and has a number of small flowers. It is in bloom from June to July. Its habitat covers an area from the bordering regions of the flat part of Srem and represents the sub-pontic-sub-mediteranean species. It grows from the lowlands to the mountainous terrains in forests or in places once inhabited by forests, in so-called stub clearings or grubbed up areas, individually or in smaller groups. It represents an indicator species for meadow communities that had been created through anthropogenic causes, i.e., through the active and intensive activity of man.
