Planinsko polje is part of the karst basin of the Ljubljanica river, and displays typical karst features such as caves (more than 100 in the vicinity) and sink-holes. Higher hills surround the IBA, from where water collects and sinks underground. Floods periodically cover about 16 km2 of the area. Besides the numerous small streams, the Unica river with its beautiful meanders is the main water-body at the site. Arable land and human settlements occur at the outermost, higher edges of the site. Land-use is mainly mowing of grass and hay; some farmers use fertilizer to increase grass production. This has been a classic area for karst research since the 17th century.
An important site for breeding Crex crex. Other wet meadow and grassland bird species breed at the site in nationally important numbers, including many SPECs. Significant proportion (³1%) of national population breeding at site: Alcedo atthis (2-5 pairs). The site is known to support notable numbers of birds on migration as well.
BirdLife International (2020) Important Bird Areas factsheet: Planina polje. Downloaded from http://www.birdlife.org on 02/06/2020.