Ócsa Protected Landscape Area

The Ócsa Protected Landscape Area is a Hungarian protected landscape area under the administration of the Danube–Ipoly National Park, whose total area is 3,606 hectares, of which 1,466 hectares are intensively protected.

Location

It lies about 30 kilometres south of Budapest, in the area bounded by the settlements of Ócsa, Dabas and Inárcs.

Characteristics

The protected landscape area was established on 9 September 1975 by decision No. 3/1975.OTVH of the President of the National Nature Conservation Office, to preserve the plant and animal rarities of deep-lying marshes and swamp meadows nestled between the Danube valley and the lowland sand areas.

The central part of the Ócsa Protected Landscape Area is one of the last remaining remnants of the marshland that once extended between the Danube and the Tisza. Its botanical and zoological rarities and values are thanks to a permanent water flow that has persisted because earlier attempts to drain the area were ineffective. The whole area is characterized by a mosaic of open waters, reed beds, meadows, forests, steppe habitats, and the corresponding traces of alternating human activities.

Formation

The marsh basins around Ócsa were created by the Ancient Danube many thousands of years ago. The former Danube floodplain’s gravel cover forms the substrate on which water from the remains of aquatic organisms and organisms created a barely permeable mud, sealing the depressions. The groundwater of the Gödöllő Hills and the Danube–Tisza interfluvial backland flows slowly south‑westward at a depth of 10–15 metres underground toward the Danube floodplain, and where the backland hills end and meet the Danube’s flat floodplain, in the Ócsa region this groundwater reaches near the surface, sometimes directly to the surface. Thus, the water coverage in the sealed depressions is almost always permanent. In such places marshes formed, or when the wetting affected the entire region, marshlands. On the marshes, organic matter from dead plants remains underwater all year, isolated from oxygen, so it does not decompose but slowly turns into a dark, water‑absorbing, fibrous material, a peat.

On the peatland, plants with special requirements, wetland rarities have settled. On the wetland's slowly warming, watery, cold soil these survived the warming following the most recent ice age, that is, some of the wetland plant species in our country are ice‑age relic plants. The interglacial picture after the ice age, the fauna linked to the varied vegetation and microclimate also remained, which is very rich both in species and in number of individuals.

Flora and fauna

Open water surfaces within the protected area can be found in the deeper lying parts, in the remnants of former moraines, river valleys, and in the much newer canals. Their banks are bordered in a wide strip by reed‑filled, rush‑laden shallows, in which the now rare wetland nettle (Urtica kioviensis) can still be found. Further away are higher, turjan‑covered areas, followed by the characteristic wetland associations, the so‑called csátés wetlands. The local inhabitants extracted the valuable fuel of the peat, the peat itself, for centuries, yet the peat areas only sharply diminished as a result of the 20th‑century spread of surrounding agricultural lands and modern water‑management efforts, therefore most of them are now strictly protected (for example the Bika‑ré t turjan). The ancient water‑course‑adjacent, less closed forest reeds have characteristic ice‑age relic plants, the wetland nettle and the wetland frog‑bit (Sparganium natans). In the drier places the blue‑eyed wetland appears, whose preservation is ensured precisely by the continuous intervention and land use of people living in harmony with the landscape, because its areas would quickly be taken over by ash‑willow (Salix cinerea) if traditional farming and regular mowing did not prevent it. On these fresh meadows still several orchid species live, and here awaits a brighter future for the valuable ice‑age relic of the area, the fragrant bellflower (Adenophora liliifolia).

The rare and valuable Hungarian narrow-leaved ash (Fraxinus angustifolia subsp. pannonica) in alder‑wetland associations, due to periodic flooding, have developed a supporting root system in the alders (stilted alder). At a higher level appears the final element of the ecological succession, the oak‑elm‑ash light forest, whose ground layer characteristically also hosts mountain species (two‑leaf shadeflower (Maianthemum bifolium), round‑leaf bellflower (Asarum europaeum), yellow arch‑bell (Lamium galeobdolon)). In the more open watery parts Menyanthes trifoliata (bogbean) grows.

The animal life of the area is also very rich. In the soils of the alder‑wetland forests specialists have found an extremely rich invertebrate fauna. The relative undisturbed nature of the area primarily benefits the bird life, but for example the number of invertebrates per square metre in the soil is also the highest in the country here. On the Ócsa Old Marsh still occur rare butterfly species such as the large reed‑brown (Nonagria typhae), as well as the “forgotten” post‑glacial silver‑banded heath (Coenonympha oedippus), which lives only here in Hungary. The common sight in the area is the marsh turtle (Emys orbicularis), but the very rare marsh fish species, the marsh perch (Umbra krameri), and the also relic viviparous lizard (Zootoca vivipara) also live here. The most precious members of its valuable bird fauna are the lesser spotted eagle (Circus pygargus), the great curlew (Numenius arquata), the corncrake (Crex crex), the European roller (Coracias garrulus), the meadow grasshopper warbler (Locustella naevia), the blue‑winged kite (Falco vespertinus), the lesser kestrel (Falco subbuteo) and the bittern (Botaurus stellaris).

Silk Meadow Educational Trail

The 1200‑metre long educational trail presenting the wetland fauna runs across the Ócsa Great Forest. The freely accessible facility can be walked in about an hour at a comfortable strolling pace. At the end of the trail, at Silk Meadow, benches and a playground await those who would like to linger a bit longer in nature. A map, the booklet leading to the trail, and a hiking guide can be obtained at the Ócsa Landscape House.