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Google map of the site

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Interventions at Merzse Marshland (blue enclaves are protected areas)

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Térkép_11 m Merzse védett és beavatkozás

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Position of the site within the country and Europe

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Water-covered (flooded, wetland) areas in Hungary before river regulation

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Location: In the vicinity of my home: Merzse Marshland Nature Reserve is a 27 ha conservation area in the outskirts of Budapest, capital city of Hungary, Central Europe.

Geography: where the Pest Plain shifts into a gently rolling landscape adjacent to Gödöllő Hills. (Runoff water supplying the marshes comes from the highest elevation: Rákoshegy hilltop 241 m). Merzse is the most extended and unperturbed wetland in the city.

There is an impermeable  clay layer (clay lens) underneath the bog to be protected to retain water

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It consist of 3 connected parts: two marshes: Great and Little Merzse and Gyolcsrét meadow spotted with groves and pastures. This wetland area is one of the few remains of one time extended lowland bogs that were characteristic throughout the plain areas of the country, including the lowland part of the capital  city. Due to river regulation (19th century) and later drainage (mid-20th c.) of marshes and bogs to acquire more land for agricultural production.

The larger bog has got floating islands and big reedbeds, while the smaller one is quite shrubby and more sheltered.

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Locally protected since 1974 - Although not a biological hotspot, but endemic fish species used to inhabit it even a few decades ago, when water was much more abundant.

Ownership: state owned area

Agriculture: enclosed by arable land (Many landowners around, mostly sharing small plots)

woodland plantations: oak (Quercus robur), silver poplar (Populus alba), white locust (Robinia pseudoacacia).

Sources of water supply: groundwater and precipitation. Thin watercourse from nearby (5 km) temporary spring which is threatened by construction works

The Merzse-marsh Nature Reserve is a popular bird-watching place

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(photo: Nathan Wilson, Mushroom Observer 396) Can be found in the autumn, while most of its relatives come out at spring. Found some in the oak woods near Great Merzse.

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There were extensive open waters 50-60 years ago, local could paddle in a  boat and catch lots of endemic fish loach (Misgurnus fossilis) as popular food. Although water was still abundant in the bogs and the wet meadows in the late 1990's, due to more frequent summer droughts it was decided to carefully dig the debris out from the lake's bottom, without harming the water  retaining clay layer.

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4 fern species,  131dicotyledons, 51 monocotyledons.
I found a strange looking fungus, white/elffin saddle (Helvella crispa).
Some protected species:
Orchid living in the oak wood:
Narrow-leaved helleborine
(Cephalanthera longifolia) see picture.  Broad-leaved helleborine (Epipactis helleborine) and Tallós nőszőfű

(Epipactis tallosii Molnár & Robatsch 1997), bitter willow (Salix eleagnos) with  distinctively narrow leaves

However, some other orchids and Colchicus autumnalis from the former wet meadows disappeared recently. Opening up meadows by grazing or taking the debris off may help them to recover.

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Mud-minnow (Umbra krameri) and European weather  fish (Misgurnus fossilis)  endemic fish species - locally extinct, but might be restored

Green lizzards (Lacerta viridis), Frogs: e. g. fire-bellied toad (Bombina bombina),
Danube crested newt (Triturus dobrogicus)
European pond turtle (Emys orbicularis)
176 bird species observed in the last 15 years - uniqueily species rich area in Budapest.
Birds: great black woodpecker (Dendrocopus major), fieldfare (Turdus pilaris) - flocks of hundreds in wintertime, mistle trush (Turdus viscivorus), waterbirds: mallard and migratory ducks, grey and red heron, great egret, Eurasian bittern (Botaurus stellaris), little grebe (Tachybaptus ruficollis), szárcsa, swan, raven, partridge
Raptors - marsh harrier, kestrel,
a tiny mammal: H azel dormouse –(Muscardinus avellanarius) - sleeps often in nest boxes

Games pecies: roe deer, hare, phaesant, occassionally wild boar

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Habitat loss of orchids,

Drop of water table, drying out, open water surface shrinked to a few hundred m² due to  former  meliorisation of arable land and gradual sanitation of urban environment.

Severe droughts

Invasive alian species: milkweed (Asclepius syriaca), goldenrod (Solidago canadensis), Koi fish (from aquarists),

New owner started clear cutting  poplar plantation (2019)

Urbanization: the marsh lays in the largest district of the city: Rákosmente (Nr. 17) (54.83 km2 , population 80 000+; the capital city has 2 million inhabitants.)

Residential home constructions, sanitation -  and motorway constructions nearby

Recreational pressure

Neighbouring international airport (conflicts with birds of preys hunting at airport fields)

Hunting (small game, roe deer)

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Arable lands surrounding the protectd area 

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Arable lands surrounding the protectd area 

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(Salix eleagnos) often forms bushes on banks/reefs. Has thinnest leaves among willows.

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an endemic and relict fish species in the Carpathian Basin, lives in bogs and swamps. Adapted to temporarily  oxygen  poor shallow waters of drying bogs. Threatened by habitat loss and invasive fish species.

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(Muscardinus avellanarius) nests in the oakwood

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Extended reedbeds and floating islands give shelter to shy, elusive  waterfowl and waders, as little grebe (Tachybaptus ruficollis) and great bittern (Botaurus stellaris)

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Birdwatching tower standing in the spring flood. (More photos: http://tortenetekkepekkel.blogspot.com/2015/03/merzse-mocsar.html)

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This dam helps retaining some of the run-off water coming from the built-in hills across the fields to the little marsh. The overflow finds its way towards the bigger marshy area.

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The expanding city is also  a threatening factor

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The expanding city is also  a threatening factor

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Bird watching hide penetrated through reedbed well into the water. In fear of  disturbing waterbirds it was demolished. A new birdwatching tower was set up instead a bit farther, near the pathway.

Artificial nestbox colony established in oak wood.  Checked regularly. Supplements the few nesting opportunities in forest plantations.

There is a signed nature trail with signboards

Occasional ornithological demonstrations held for the public  (birdwatching and ringing  events )

Photo: The old hide

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Story 3. Recent/planned habitat management actions: 

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Story 3. Recent/planned habitat management actions: 

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Conservationists have cut few times rush to open up a bigger water surface

Some dikes were redirected (still to be deepen and clear of deposited waste and earth) to secure water supply. To be continued.

Dam strengthened at Little Merzse marsh, pool is filled with water, ducks returned

Faunistic survey of fish species and aquatic plants is planned by conservationists

Marsh harrier hunting (photo BŁOTNIAK STAWOWY)

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Local efforts focused on possible means of wetland restoration > stable water supply, wet meadows >  habitat restoration for recently locally extinct species - good examples from an NGO: http://www.tavirozsa-egyesulet.hu/publikaciok/Termeszeti_kincseink_vedelme_tom.pdf

Large open water surface exists year-long again since 2014, following habitat management (bulrush cutting)

Improving conditions by water management to restore and stabilize adequate water level at Little Merzse (see actions)

Through a connecting canal overflowing water would supply Great Merzse

Photo: Danube crested newt (Triturus dobrogicus)