Specific conservation actions
C.1a Restoration of the Čiližský potok stream
Restoration of the Čiližský potok stream in its entire length of 33.5 km is one of the most significant project activities. In the past, there were numerous wetlands in the catchment area of the stream. Most of them were drained and transformed into arable land, while in others, the water level decreased because of water management and ameliorative interventions in the past centuries. The planned changes of water regime in the Čiližský potok stream will contribute to the improvement of hydrological conditions; the water level will be the same as in 1950–1970 when root vole used to be much more abundant in this area.
The Čiližský potok stream is one of the last water courses with natural character in the Slovak part of the Danube Lowland. Its meandering course flows through the central part of the area with the occurrence of root vole and it works as its natural habitat corridor. However, with regard to the series of water management and agricultural interventions carried out in the last century, a free water flow in the Čiližský potok stream can be seen only in its upper part today. Diversion of its water into intersecting drainage channels resulted in a loss of water in its original bed and, as a consequence, two thirds of the stream lack flowing water or are completely dry.
Based on a study by the Water Research Institute (Project activity A.3) and in cooperation with several project partners, key institutions and organisations, following measures have been proposed for the restoration of the Čiližský potok stream:
A culvert at the crossing of the Čiližský potok stream and Chotárny kanál canal is the largest and most demanding structure in the process of the stream revitalisation. Chotárny kanál canal has been an important canal since it was built at the turn of the 19th and 20th century. In the past, the crossing with the Čiližský potok stream occurred thanks to a culvert built in 1938 when Chotárny kanál canal was led under the stream. After some time, the outlets of the culvert became blocked by alluvial material from Chotárny kanál canal and it was impossible to remove it. In the 1980s, a by-pass was built around the no longer functional culvert considering the necessity of using the canal. In this locality, the flow of Čiližský potok stream was disrupted and approximately one kilometre from the crossing with the channel (locality Šarkan), water flows from the stream through an overflow directly into Chotárny kanál canal. The present proposal for restoration of free water flow includes removal of the old culvert and its replacement with a new one which, however, will lead the Čiližský potok stream under the canal and then the stream will connect to its original bed. A non-functional culvert was demolished in April 2014, works on construction of a new culvert started in the end of July 2016 and we suppose it to be finished in October 2016.
The Čiližský potok stream is disrupted for the second time by Vrbina-Holiare canal into which the flow from the middle part of the stream is discharged through a culvert. Nowadays, it contains only rainwater, as the culvert with Chotárny kanál canal is no longer functional. Further from the crossing, there is no flow at all in the stream. In the place of crossing with the Vrbina-Holiare canal a new culvert was built in July 2016 to support the lower section of the stream with water in the length of approx. 5 km.
Until the end of the 18th century, the Čiližský potok stream flew directly into the Danube and since 1798 into Číčovské rameno oxbow lake where a sluice was built in 1860. The completion of the network of drainage channels after 1960 has completely cut off the lower section of the stream, so there was no water left in it. Measurements during the preparation of the restoration of the Čiližský potok stream have shown that it is not possible to connect the stream to Lyonský kanál canal near Číčov because of a difference in height between the canal bed and the stream bed and the stream would flow back towards the culvert on Vrbina-Holiare canal. For this reason, it was proposed that a new meandering bed in the length of 1.8 km should be built in Číčov and the Čiližský potok stream should be then connected to Číčov-Holiare canal.
To restore free water flow in the Čiližský potok stream, it is necessary to clean some overgrown and blocking sections (e.g. near Gabčíkovo, Pataš and Čiližská Radvaň). The most intensive works were carried out in 2012 when BROZ in cooperation with the town Veľký Meder removed an illegal landfill from the bed of the Čiližský potok stream containing mainly industrial and domestic waste. The landfill was near Ižopská samota in the county of Veľký Meder and it had blocked about 650 m of the bed. Approximately 300 tons of waste was removed from the locality. The works continued in spring 2014 - we removed silt deposits from 250 m long section of the brook in Pataš village.
Restoration of wetlands near the Čiližský potok stream with the occurrence of root vole focuses on two localities: a locality Bahno near Pataš village and a locality Čiližská mokraď wetland near Čiližská Radvaň village. In Bahno, there will be a change in water regime due to building of the culvert on Chotárny kanál canal which will enable the water to flow not only in the stream, but thanks to sluice regulation, it will be also possible to inundate the wetland. Restoration of water regime in the wetland near Čiližská Radvaň will be achieved through reconstruction of existing non-functional sluice gates on Hánsky kanál canal and through building a new sluice gate on Červený kanál canal. Thanks to them, it will be possible to retain water accumulated in the wetland during periods of rain and to regulate the duration and periodicity of periods with various water levels. Works on wetland restoration began in spring 2014 starting with construction of a sluice gate on Červený channel. Since the sluice gate construction in 2014 the water level in wetland is closely observed by project partner VUVH (Action E.2). The area of wetlands restored by the constructed sluice gate is 82.5 ha large.
C.1b Inclusion of restored areas in the vicinity of the Čiližský potok stream in the NATURA 2000 network
The Čiližský potok stream and adjacent wetlands are only partially included in the NATURA 2000 network. Some areas affected by the project are not included in the NATURA 2000 network, but after successful conservation measures, they will be designated and will become a part of this network.
Ministry of Environment of the Slovak Republic has sent European Commission an Amendment to the National List of Special Areas of Conservation. SAC Čiližské močiare (SKUEV1227) has been included within 97 new or enlarged Special Areas of Conservation in Slovakia. Proposed SACs will represent an enlargement of existing SAC Čiližské močiare (SKUEV0227) and will include central part of the Čiližský potok stream as well as the wetland in Čiližská Radvaň. Thus, the area will be enlarged by 329.58 ha (present land area is 61.48 ha) and will extend to six cadastral areas (villages Číčov, Čiližská Radvaň, Ižop, Kľúčovec, Pataš, Gabčíkovo and town Veľký Meder).
C.2 Restoration of wetlands in the area of Číčov - Gabčíkovo
After the series of water management measures, remediation schemes and changes in landscape use in the last 50 years; conditions that were once favourable for root vole have changed dramatically. The most serious consequences were caused by cutting off of the last section of the Čiližský potok stream originally flowing into the area of Čiližské mokrade wetlands through building a dike, digging drainage canals through Hámske tŕstie wetland and by transformation of wetlands into fish ponds and arable land.
In 2013, restoration of Číčovské wetlands in locality Hámske tŕstie has began in the area of 46,5 hectares. A sluice gate on existing drainage channel has been reconstructed to keep necessary water level in the wetland. Further restoration activities are planned to be carried out in 2014. Nowadays, measurings of water levels for bringing water in the wetlands near Gabčíkovo are being assessed.
Restoration of the wetland Hámske tŕstie in SCI Číčovské wetlands continued in 2015 by revitalising another 31,1 hectares. Area as large as 24,8 hectares in SCI Číčovské luhy consisting of marshes, shallow ponds, reed beds and sedge vegetation was restored after it was used as transport and storage area for harvested wood. Restoration of other wetlands in Číčov – Gabčíkovo area started in August 2014 and consequently these wetlands were created by the end of 2015 – localities Vojka (24,3 hectares), Baka 1 (14,2 hectares), Baka 2 (3,7 hectares), Baka 3 (1,7 hectares), Číčov 2 (6,22 hectares), Baka 4 (3,1 hectares) Baka 5 (1,7 hectares), Baka 6 (2,71 hectares) and Baka 7 (6,2 hectares). In total 166,23 hectares were restored, which is 16 hectares more than it was planned in the project.
C.3 Restoration of selected wetlands important for root vole
On the basis of a mapping of the actual occurrence and the state of the population (Activity A.1), other localities were selected for the improvement of life conditions of root vole. Water management research (activity A.4) examined possibilities to improve water regime in these localities. Measures for restoration of at least 250 hectares of wetlands will include mainly building of minor objects (dams and sluice gates) on minor canals and drainage ditches used at present for the drainage of wetlands. Thanks to new objects, it will be possible to maintain the water accumulated during periods of rain in the wetlands. Sluice gates will enable regulation of water level and the length of the periods with various water levels. Throughout the activity A 4 proposals of the models for the restoration of following wetlands have been assessed: models for restoration of Listové jazero wetlands (Nesvady and Vrbová nad Váhom counties), Martovská mokraď, Alúvium Starej Nitry (Martovce county), Pohrebište (in Marcelová municipality) and Dunajské trstiny (in Veľké Kosihy municipality).
In 2015 one of the wetlands was restored in SCI Alúvium Starej Nitry in cooperation with local agricultural company and major owner of the land. 9,8 hectares of marshy meadows and reed beds was created this way. Restoration of other 48,6 hectares was done by installation of sluice gate on the outlet of drainage channel from the wetland. A sluice gate on Tavarský channel was built in the autumn/winter 2015 restoring 108.9 hectares of the wetland in lower part of the SCI Dunajské trstiny near Veľké Kosihy village; the upper part will be restored on the area of 18.7 hectares. Water regime in SCI Pohrebište will be restored on 47.5 hectares and in Martovská mokraď on 33.6 hectares.
C.4 Restoration of grassland habitats
In the past, lowland meadows and pastures used to be very common in the Danube Lowland. They were found in areas unsuitable for arable land with high groundwater level and they represented important habitats for root vole. Because of drainage systems and soil remediation, most of the areas were ploughed up and transformed into an intensively used arable land with agricultural crops.
Restoration of grassland habitats includes cutting neglected vegetation on the edge of fields and wetlands overgrown with invasive and expansive species as well as the transformation of arable land into grassland by sowing grass and herb seeds typical for this region and by introducing regular management through cutting in the total area of at least 100 ha. Restoration of grassland habitats is concentrated in localities with the occurrence of root vole with the aim to create suitable habitats and thus extend localities of its occurrence. In 2011 and 2012, 11.3 ha of meadows were cut on minor spots in the sites of community importance (6.3 ha in SCI Dunajské trstiny and 5 ha in SCI Šúr) within the project. In 2012, we started establishing grasslands in the area of 16.2 ha in Site of Community Importance SKUE1227 Čiližské močiare (cadastral area of Čiližská Radvaň), in 2013 we continued on additional 6,2 hectares. The created grasslands replace arable land intensively used for agricultural production. After building the sluice gate on Červený kanál canal (Activity 1a), they will be periodically inundated. At last, the created grasslands will extend the habitat of root vole in the locality with one of the most significant populations of this species in the world. Grasslands were mowed several times in wide stripes to let grown vegetation for root voles living in this area as the refuge against predators (until the vegetation in mowed stripes is not grown-up yet). By mulching and mowing we also restored an overgrown wetland in Dunajské luhy in the area of 4,9 hectares and a wetland in Čiližská Radvaň in the area of 12,6 hectares.
Later in 2014/2015 another hectares of grasslands were restored - 26,2 hectares in SCI Číčovské luhy, 8 hectares in SCI Dunajské luhy, 6,5 hectares in SCI Alúvium Starej Nitry and 11,6 hectares in UEV Martovská mokraď. The restoration included mowing, mulching or seeding regional seed mixtures.
C.5 Reintroduction of reed beds management
Most localities with the occurrence of root vole lie outside the active floodplain and growing reed contributes to increasing sedimentation and clogging of wetlands, which leads to transformation of ecosystems into dry habitats with time. Reed cutting is a good example of how to manage and preserve wetlands.
In the winter season 2011/2012, we started the first reed cutting in the Site of Commnity Importance Dunajské trstiny in the area of 13,5 hectares. Reed cutting is performed in winter months, outside the nesting period of birds using reed. When cutting, we leave stripes of uncut reed in the area serving as a temporary refuge for animals until the time the cut reed grows again. In winter 2012/2013, we continued with reed cutting adding 38,1 hectares, in 2013/2014 adding another 86,11 hectares in Sites of Community Importance Dunajské trstiny and Číčovské luhy. The overall objective of the project is to cut 150 hectares of reed.
The localities already cut in the past within the project in SCI Dunajské trstiny and SCI Číčovské luhy were mowed repeatedly in the winter season 2014/2015. Two localities were added in SCI Čiližské močiare (5.4 hectares and 6.3 hectares) and previously uncut locality in SCI Dunajské trstiny (6 hectares) was added as well in the season 2014/2015. In the winter season 2015/2016 we continued in reed mowing in SCI Dunajské trstiny and SCI Číčovské luhy. The overall area of managed reed beds covers 155.48 hectares.
C.6 Creation of habitat corridors between the localities with the occurrence of root vole
Arable land represents a migration barrier for root vole. As a result, its population became strongly fragmented in an intensively used land after it had been drained and ploughed up. Isolation of these populations may cause complete extinction of root vole as a result of a genetic deformation.
By planting native trees and bushes and creating grass stripes or higher herbal vegetation, we will create at least 10 500 m of habitat corridors along water courses, old river branches and wet depressions in the country. The purpose of these corridors is to connect root vole populations not only to secure the exchange of genetic information between populations, but also to distribute this species into new localities and restored habitats.
Planting of biocorridors began in autumn 2013 in an important locality with the root vole occurence near Čiližská Radvaň in the lenght of one kilometer. In the line vegetation we planted 13 species of native trees and shrubs suitable for wet conditions (willows, poplars, common dogwood, bird cherries, mountain-ashes, common hawthorn) in the overall number of 500 trees and shrubs.
In 2014/2015 the action continued in other SCIs where biocirridors were proposed by the study. Biocorridors were planted in following SCIs: Čiližské močiare (in locality Bahno 350 trees were planted in length 1.4 km and in locality Pataš along Čiližský potok brook in length 250 meters), in SCI Dunajské trstiny created biocorridors connected localities of root vole in length 1.5 km by planting 370 trees, in SCI Dunajské luhy 4 km of biocorridors were planted with 2000 trees and in SCI Číčovské luhy 2,5 km of biocorridors were created.
