Grmoščica Forest Park

About

Grmoščica or Grmošćica is a hill on Medvednica mountain in central Croatia, just north of Zagreb. Its highest peak is 239 m.

The form Grmoščica is Kajkavian, whereas the form Grmošćica is a correction according to the Croatian standard. It consists of a root inherited from Proto-Slavic grъmъ + -oš + -čica. A dialectal form Grmovčica is also encountered. Both spellings continue to be used. Certain historical forms attest to grmļski + -ica.

In other dialects, the word grmoščica is used to refer to the mushroom Desarmillaria tabescens or Armillaria tabescens.

Trees include Castanea sativa, Fagus sylvatica, Quercus petraea, Salix alba, S. purpurea, and others.

There is currently a Robinia pseudoacacia infestation, and foresters are trying to force the growth of native Q. petraea and F. sylvatica to combat it. The local C. sativa population is still badly affected by Cryphonectria parasitica.

The lichen species found on oak bark on the hill are Flavoparmelia caperata and Hypogymnia physodes.

Basidiomycetes include Amanita caesarea, Hygrophorus eburneus, Laeticutis cristata, Lycoperdon perlatum, Russula cyanoxantha.

Insects include Subcoccinella vigintiquatuorpunctata and the invasive species Dryocosmus kuriphilus, the latter a risk for the spread of Cryphonectria parasitica.

Trees include Castanea sativa, Fagus sylvatica, Quercus petraea, Salix alba, S. purpurea, and others.

There is currently a Robinia pseudoacacia infestation, and foresters are trying to force the growth of native Q. petraea and F. sylvatica to combat it. The local C. sativa population is still badly affected by Cryphonectria parasitica.

The lichen species found on oak bark on the hill are Flavoparmelia caperata and Hypogymnia physodes.

Basidiomycetes include Amanita caesarea, Hygrophorus eburneus, Laeticutis cristata, Lycoperdon perlatum, Russula cyanoxantha.

Insects include Subcoccinella vigintiquatuorpunctata and the invasive species Dryocosmus kuriphilus, the latter a risk for the spread of Cryphonectria parasitica.

An approximately 20 metres (66 ft) thick open profile of terrestrial non-carbonate loess can be observed in the former clay pit of Grmiščica. These Quaternary deposits were sampled in 2017 and determined to belong to the Bistra unit. They are not separated from the underlying Upper Pliocene strata, which are exposed on the northern flanks of Grmoščica. Fossils of fish and mammals have been found on the southeast flanks of the hill.

Tectonically, Grmoščica is transected northweast-to-southwest by a relatively lowered block.

Grmoščica is home to some of the most active landslides in Zagreb. A large area of the forest on Grmoščica is under private ownership, which has resulted in forest loss, which has led to landslide formation. The main landslide, the Grmoščica Landslide, spans an area of 2 hectares (4.9 acres), with a depth of 5–9 metres (16–30 ft). The first, partial stage of landslide remediation was completed at the end of 2007, in response to some recent wet mass movement. Some have had to leave their homes because of the landslide even after remediation. The landslide is still active as of 2025.

See also: List of caves on Zagrebačka gora

Kustošijanka is a cave with two entrances and 44 m of passageway on the north slope of a valley on the east side of Grmoščica. It is located on the fault line dividing Grmoščica in half from northeast to southwest. Its entrance is at an elevation of 155 m. The caver Darko Višek learned of its existence in conversation with local resident Vlado Krapljan, who was among the visitors who left many names and dates inscribed on the walls of the cave in their childhood. It formed in Upper Pontian layers of marlstone, duststone, and sandstone : " Rhomboidea layers", deposited in brackish conditions. Thanks to being on a landslide-prone part of the hill, the entrance became covered at some point after 1993 and could only be passed following digging in 2010.

An approximately 20 metres (66 ft) thick open profile of terrestrial non-carbonate loess can be observed in the former clay pit of Grmiščica. These Quaternary deposits were sampled in 2017 and determined to belong to the Bistra unit. They are not separated from the underlying Upper Pliocene strata, which are exposed on the northern flanks of Grmoščica. Fossils of fish and mammals have been found on the southeast flanks of the hill.

Tectonically, Grmoščica is transected northweast-to-southwest by a relatively lowered block.