Marsh on the edge of the capital: nature trail at Merzse marsh

Itinerary: 

The nature trail marked with separate signs presents one of the most important and at the same time most unique nature conservation areas in Budapest through 15 information boards. The trail can be followed with the help of the map placed on the boards. 

• At the Merzse parking lot, we find the second board (the first is at the railway station), and if we stand facing it, about 50 meters to the right is the third board. However, instead of this, start to the left from the starting board at the clearly visible trail marking.
• The trail first circles the Large Merzse and touches boards 4-9, as well as the birdwatching hut. At the ninth board, turning right we can circle back to the parking lot completely around the Large Merzse (short loop), turning left at board 9 gives us the option of the large loop.
• On the large loop, we first reach the second protected area, the Gyolcs meadow (board 10), then leaving it, the trail turns right onto a large meadow road. With the 11th board and the enclosed Small Merzse, we come out onto an acacia tree lined lane, where we find board 13. (Turning left from board 13, after a few hundred meter detour, we reach board 12.)
• Here turning right and going straight along the tree lined lane (passing boards 14 and 15), we return to the continuation of Lapos-dűlő, where turning right we walk back to the Merzse parking lot. 

Detailed description of the hike

The nature conservation values of the Merzse marsh

It is almost unbelievable that despite the strong expansion of the capital, several parts of the once large Rákos marshland have survived to this day. These areas, embedded in the fabric of the city, are strongly degraded yet worthy of protection flat areas (e.g., Felsőrákosi meadows, Naplás lake, Soroksár marsh) which count as significant wet habitats, especially in a booming metropolis. The marshy area typical of the Pest side of the Danube was very diverse and extensive, even starting from the Grand Boulevard 150 years ago. In Budapest, which shows one of the fastest urban development rates in the world, it is a wonder that these few habitats have remained intact among inhabited and agricultural lands. Similar to the above mentioned areas, even in its degraded state, the Merzse marsh surprisingly hosts rich flora and birdlife, definitely worth discovering!

As we read on the second board at the parking lot (General introduction to the Merzse marsh Nature Conservation Area), the Merzse marsh Nature Conservation Area, protected since 1977, consists of three parts, two of which are wetlands (Large and Small Merzse), and the third is a wooded grove, specifically a remnant of a softwood grove forest. The Large Merzse boasts the largest contiguous reed bed in the capital, over which the brown marsh harrier's flight is a nearly usual sight. The Small Merzse is an untouched marsh; the biggest sensations of Gyolcs meadow are the poplar old-timers. The area is surrounded by a protective zone (farmlands and forests), and the more distant parts of the trail allow a glimpse into their wildlife. At the start, we also learn that the trail design took children into account, as besides the usual information boards, each also features a drawing explanation and a smaller board with test questions within the nature conservation area.

The magical secret of the antlion butterflies

Before setting out, it is worth reading the meadows and hayfields world presenting third board, where we learn that the prominently significant, Red Book (endangered) bloodroot-antlion butterfly also lives around the marsh. Antlion butterflies are symbols of nature conservation, as their life is incredibly closely intertwined with a plant and another animal species. The butterflies lay their eggs in the autumn bloodroot's inflorescences, where the small caterpillars feed on the seed buds for some time but do not exhibit excessive growth. After the third molt, they drop to the ground, where workers of certain ant species carry them into the ant nest after appropriate ritual contact. There, their further development takes place as nest parasites. This means they either eat the ant larvae or are fed by the workers as cuckoo chicks to complete their development. Their protection and feeding are ensured by the ant colony. The substances found on the larval surface during their time in the nest make the ants not consider them enemies (chemical mimicry). However, these substances are absent on the adult butterfly, meaning the butterfly must swiftly escape the ant nest after emergence, or the 'stepmothers' will kill it. Because of the high degree of symbiosis, antlion butterfly species are much more sensitive to changes than average, so their populations have drastically decreased in developed agricultural Western European countries. Yet, at the border of the capital, such wonders can still be found!

Birdwatching hut at Large Merzse

Starting on the trail, on the right soon appears the reed bed, on the left a beautiful oak forest – a great demonstration of the mosaic habitat complex typical of the area, alongside agricultural fields, their "guardian" rows of trees, and further away gardens. The diversity can be felt: on the left, a forest finch is singing, the cuckoo provides the base note, and on the right, the reed warbler’s unmistakable song fills the reed, especially if not overwhelmed by the neighboring garden nightingale’s battle. The oak forest visible here was actually planted in the 1970s, during the great forest planting in Pest, as reported also by the board 4 (Planted pedunculate oak forests in Merzse).

After a huge willow tree leaning over the road, our path turns right, and at board 5 (Water birds, reptiles, amphibians) we get acquainted with the birdlife of Merzse, which perhaps represents the greatest nature conservation value of the protected area. To date, more than 175 bird species (!) have been observed in Merzse, almost half of the species documented in the country! Moreover, during spring and autumn migration, rare species such as the marsh harrier, little egret, or black stork are observed here. From the birdwatching tower inaugurated in 2015, even enthusiastic amateur birdwatchers in spring can catch sight of the regularly nesting brown marsh harrier, and the Large Merzse's reeds and the open water body in the middle are filled with the songs of ducks, coots, water rails, and reed warbler species.

Additionally, in the spring sunshine, many beautiful green lizards can be seen, and from the birdwatching hut, we can understand how anthropogenic impacts causing the drying of Merzse lead to the reed becoming overgrown with trees, as the board 6 in front of the tower poignantly explains (Succession and area maintenance). Under the tower are resting benches and board 7, which presents invasive species threatening the area. Moving further along the path, even a layperson can notice the presence of invasive species, as the path leads for a good stretch in a species-poor acacia plantation (though white acacia was also deliberately planted here for forestry purposes, as we read on board 8 (Acacia-white poplar plantations). Another characteristic tree species in this part of Merzse is the white poplar, which very likely was originally also present here.

At board 9 (Factors endangering Merzse) we must decide if we return via the shorter loop to the parking lot or explore Merzse fully on the large loop. With children, the shorter route is recommended, as the second section of the trail offers fewer sights and involves longer walks. Heading right to the parking lot, first on a meadow road, then back to the nature conservation area, we can walk back through the forest.

From Gyolcs meadow to Small Merzse

Turning left, we move along a long straight road, and after a few hundred meters, to the right we find Gyolcs meadow and its wildlife presented by board 10 (Gyolcs meadow: natural forests and practical nature conservation at Merzse). Around Merzse there was far less forest in the past than today; Gyolcs meadow is a groved-shrubby, just reforested, secondarily formed habitat. After Gyolcs meadow, a longer walk awaits, then we turn right onto a wide meadow road. We cross the meadow, then reach board 11 at the edge of the Small Merzse (The Small Merzse). The 10-hectare protected marsh’s fauna is the same as the Large Merzse’s but more undisturbed, so we cannot enter the marsh. Since the Small Merzse retains water more reliably, species relying on the Large Merzse, which dries out cyclically, can survive dry periods here.

Field protective forest belts

Continuing straight from Small Merzse, we soon reach the far side of the meadow and the protective forest belt there. This is what board 13 at the crossroads talks about (Field protective forest belts). Huge agricultural fields stripped of their natural vegetation are not only physically damaged by wind (windbreak damage, snow drifts), but the drying is also significantly contributed to by this. Properly positioned forest belts greatly prevent all this and serve as ecological corridors providing shelter for many animals, especially if wider and with shrub layers.

With a few hundred meters detour to the left, we can also approach board 12 (Merzse's water catchment area and watering paths). This board, crucial for understanding Merzse as a habitat, nicely describes how the former so-called micro-relief landscape, with marsh meadows in depressions and sandy grasslands about 2 meters higher, changed with the appearance of agriculture. To protect arable lands, drainage networks were constructed, so less and less water reached above the clay lens below the marsh, thus Merzse dries out.

Returning along the straight-lined tree alley onto the dirt road continuing Lapos-dűlő, turning right takes a few minutes to Merzse parking. Along the way, we pass board 14 (Artificial water replenishment at Merzse) and board 15 (Agriculture and the fauna of agricultural areas). To prevent Merzse from drying out, the City Municipality tried in the 1990s to improve the water supply of the Large Merzse with water from boreholes (as mentioned, the Small Merzse’s water supply is much better, so no water was led there). However, the system was shut down because partly too much water evaporated and partly because some boreholes were so deep that they basically extracted water from the clay lens under the marsh, at least partially. The marsh often dries out, but periodic drying is a natural process in the life of a marsh. The problem here is that due to the significantly altered water catchment area by humans, drying occurs more often than naturally at Merzse. Signs of agriculture established on the wet meadows surrounding the marsh are still visible today: along the road, several abandoned wells are seen where grazing ceased.

If the sign of a fulfilling family hike is learning to (re)discover our immediate surroundings, then the Merzse marsh Nature Conservation Area is a perfect place for a little exploration and wonder!