Prašnik is located near the village of Novi Varoš, 8 km southeast of Okučani.
It is considered to be the only original remnant of the famous Slavonian pedunculate oak forests that stretched in the valleys between rivers Sava and Drava. At the initiative of the forestry profession in 1929, this rainforest with an area of about 50 ha was exempted from management for the purpose of education and research. It was declared a special reserve in 1965. The public institution Natura Slavonica has been managing this area since 2004. After the Homeland War the area of Prašnik was under landmines and has finally been demined 2015. After that, the University of Zagreb, Faculty of Forestry, began intensive research in the area. Bat species were also studied through the Sava Bats project implemented by Public Institution Natura Slavonica and funded by EuroNatur, Aage V. Jensen Charity Foundation and Michael Otto Stiftung.
Today, Prašnik is visited mainly by announced groups of experts in the field of forestry and biology. The plan is to build a visitor centre equipped with multimedia facilities in the immediate vicinity of the rainforest.
Prašnik is a forest of pedunculate oak and hornbeam (Subas. Carpino betuli-Quercetum roboris "typicum" Rauš 1973) and Natura habitat 9160 of Sub-Atlantic and medio-European oak or oak-hornbeam forests of the Carpinion betuli. There are 3 age groups of oaks in Prašnik: 60-70 years old, 150 years old and 210-290 years old trees. This oldest age group includes more than 1000 oaks on an area of 50 ha. Tree (dead or alive) removal and any forest management are prohibited in the reserve. An initial survey of bats was conducted in 2016, as part of the Sava Bats project, when as many as 8 species of bats were recorded in two field trips. Out of these species, two are Natura species listed in the Croatian Red Book of Mammals (Antolović et al. 2006): the western barbastelle (Barbastella barbastellus) and the Bechstein's bat (Myotis bechsteinii). The project and research were implemented by the Public Institution Natura Slavonica and funded by the EuroNatur Foundation, the Aage V. Jensen Charity Foundation and the Michael Otto Stiftung.
The largest oak in Prašnik sprouted around 1675. It is taller than 40 meters, has two and a half meters in diameter, and it was nominated for the Croatian Tree of the Year in 2019.
Known about the unknown
Prašnik is the only original remnant of Slavonian oak forests that Josip Kozarac, who worked as a forester in the vicinity of Okučani, wrote about in his short story "Slavonska šuma" ("Slavonian Forest"). Here is a quote from the aforementioned story: “Whoever was once in that ancient forest of ours and saw that neat, clean and tall tree, beautiful as if molten, can never forget it. In there, majestic oaks rise, with their greyish bark, straight furrows running along the entire 20-meter-high trunk, a strong broad canopy crowning them, as thick hair crowns a hero's head. They proudly line up next to each other, like soldiers at the Military Frontier, telling their story of giants, defying storms and lightning, the strongest and noblest in their kingdom and tribe."