In the paper was investigated the variability of the morphological and anatomical traits of one-year-old seedlings of different species from the genus Quercus (Quercus robur L., Quercus petraea Matt. Liebl. and Quercus frainetto Ten.) cultivated in a plastic container Bosnaplast 18. The acorn was sown in November 2022, while the measurements of the studied elements were performed at the end of the growing season next year. In terms of morphological characteristics, the highest mean values of both researched parameters (root collar diameter and height) were recorded in Q. robur, followed by Q. frainetto, while the lowest mean values were found in Q. petraea. As for anatomical parameters, the following were analyzed: vessels width, the proportion of bark, pith and wood, as well as the participation of early- and latewood zones. Vessels width shows the least average values in Q. petraea, while no significant differences were recorded between Q. robur and Q. frainetto. The highest presence of wood, as well as the early zone within it, was found in Q. robur. The proportion of bark is a little bit higher in Q. frainetto compared to the other two species, while the pith proportion is significantly lower in Q. robur than in the other two species. Based on the obtained results, we can conclude that Q. robur seedlings show the best performance, before all from morphological point of view.

Lowland pedunculate oak forests in the alluvium of the river Sava are of a great economic and ecological importance. Their growth and development features, and their survival, as well, mostly depend on soil moisture and available water. The paper deals with the influence of groundwater level on pedunculate oak forests condition in flooded area of Donji Srem. During four-year long research, the average (reference) groundwater level was determined, and extremes, the wettest and the driest year, were determined based on climate factors such as temperature and rainfalls. Deviation of the average from the reference groundwater level in the vegetation period during some years indicates possibility of risk zones presence. These zones are defined according to geostatistical analysis – ArcGIS, Kriging model and they are very significant for forestry practice, because they can predict some drought events and warn forestry experts to react in time in order to prevent big damages. Bearing in mind that investigated area is flooded, and that groundwater level is close to the soil surface, these anaerobic site conditions are obviously more suitable for another hygrophilous species than for pedunculate oak.