Diversity of Pedunculate Oak Forests in Posavina

Hrast lužnjak (Quercus robur L.) najrasprostranjenije je stablo nizinskog pojasa kontinentalne Hrvatske. Kao takvo gradi dvije šumske zajednice, a u još nekoliko njih zastupljen je u flornom sastavu. Najveće šumske komplekse tvori u Posavini. Ovaj rad daje kratak pregled šumskih zajednica u porječju rijeke Save u kojima je hrast lužnjak edifikator. Ključan čimbenik koji uvjetuje rast i razvoj lužnjakovih šuma je voda, koja se u nizinskom ekosistemu može pojaviti kao poplavna, podzemna i oborinska. U ovisnosti o spomenutoj vodi, ali i mikroreljefu, razvijaju se dvije tipične asocijacije, a to su šuma hrasta lužnjaka s velikom žutilovkom (Genisto elatae-Quercetum roboris), koja se razvija na nižim i vlažnijim staništima, i šuma hrasta lužnjaka i običnog graba (Carpino betuli-Quercetum roboris), koja se razvija na uzvisinama van dohvata redovitih poplavnih voda.Pedunculate oak (Quercus robur L.) is most widely distributed three in lowland belt of continental Croatia. It forms two forest communities and in several more it is represented in the flora composition. It forms the largest forest complexes in Posavina. This paper provides a brief overview of forest communities in the Sava river basin in which the pedunculate oak is the edifier. The key factor that conditions the growth and development of pedunculate oak forests is water. Water appears in the lowland ecosystem as flood water, underground water and precipitation water. Depending on the water, but also on the microrelief, there are two associations of pedunculated oak forests. The first one, which develops in micro-hollows is the forest of pedunculate oak with great greenweed (Genisto elatae-Quercetum roboris). The second one, which develops at microelevations is the forest of pedunculate oak and common hornbeam (Carpino betuli-Quercetum roboris)