The county has three main relief forms – the mountains (the Dilja, Papuk and Požega mountains), the lowlands (occupies most of the County) and the valleys (around the Sava River).Primary ecological systems are forests and wetlands, cultivated areas (grasslands, arable land, orchards and vineyards), artificial water systems (reservoirs, ponds) and forests. About 30% of the county is covered with forest – beech and hornbeam forests in mountainous parts, and oaks mixed with ash, elm and linden in the lowlands. Water and wetlands are important ecological systems in the County, high in terms of biodiversity and landscape diversity. There are several protected areas along the Sava River – Jelas Polje and Bara Dvorina and part of Lonjsko Polje in the east. It is not surprising, therefore, that fishing is an important economic activity, and artificial ponds have created their own distinctive ecosystems that replace wetlands, which, due to reclamation, have largely disappeared. Existing ponds and remaining wetlands are important habitats for wetland birds, wildlife, and two ornithological reserves have been established in the County.