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Preparatory actions

A1. A study on the present occurrence of root vole in the project area

The research of Faculty of Natural Sciences of the Comenius University in cooperation with the colleagues from Austria, Hungary, Slovakia and Netherlands focuses on present knowledge about spatial distribution of root vole in Slovakia, Hungary and Austria. It includes field research (trapping into restraining traps) and its analysis as well as processing of already published information. The research is aimed at examination of localities with the occurrence of this species, estimation of the population size and the size of the areas in which root vole populations are found. Moreover, distances between individual localities where the species occurs, but also localities that it might expand to after the completion of the project, are being examined.

The research and monitoring localities were selected based on existing knowledge about spatial distribution of the species and from the maps of landscape elements which could indicate the occurrence of root vole. The collection of samples in the field includes trapping into wooden restraining traps and marking by ear tags. To assess the presence of root vole in owl’s food, researchers carry out an analysis of owl pellets.

Collected data is compared with the database of the occurrence of target species in Slovakia. Current list of localities with the confirmed occurrence of root vole and a current map of its distribution has been created. The research aimed at discovering the presence of small ground mammals was conducted in 2010–2012 in 73 localities; the presence of root vole has been confirmed in 29 localities with more than 300 individuals trapped. These localities are concentrated in three relatively isolated areas – one around Čiližský potok stream (in particular near Pataš and Čiližská Radvaň), one around the Danube (in particular in the wetlands near Veľké Kosihy and Číčov) and one near the original river branch of the Nitra (near Martovce). The most significant locality of the occurrence of root vole in Slovakia is the wetland near Čiližská Radvaň. In 2013, the occurence of root vole was detected in the locality west from Gabčíkovo in the inundation of Danube. It had not been expected to detect this species here due to the impact of Gabčíkovo Dam and resulting changes in water regime.

A.2 A background research study on population ecology, genetic variability and habitat requirements of root vole

The Faculty of Natural Sciences of the Comenius University is also elaborating a genetic and ecological study of root vole serving to estimate relative genetic variability and degree of isolation of individual populations of the species as well as a study of optimal habitat characteristics for this species.

In localities where the occurrence of root vole has been confirmed, a long-term population study has been conducted by means of repeated trapping into wooden restraining traps. Two such localities were chosen – in Čiližská Radvaň and in Veľké Kosihy. Information about age structure and reproduction status is being assessed and tissue samples of the individuals are being collected for molecular analysis. The analysis will enable to assess the degree of genetic fragmentation of populations in the area. The first results show the existence of four genetically different and isolated root vole populations in Netherlands, Austria and Slovakia. The fourth group comprises population occuring in Slovakia, however this group is separated from others by Danube and Gabčíkovo Dam. A research continues with the aim to search for relations with Hungarian population.

 In 2014 the research on Moe population continued. Recurrent catchments of Microtus oeconomus mehelyi individuals were carried out using quadrate method. The DNA analysis was carried out with interesting preliminary results. Consequently using Mantel test the relationship between genetics and geographical distance was also studied.

A.3 Elaboration of an expert study on restoration of water regime in the Čilizsky potok stream and its catchment area in the area of Gabčíkovo – Číčov

In 2010 and 2011, Water Research Institute worked on an expert study which included hydrodynamic, topographic, numerical, simulation and physical model, graphs and maps which serve as background documents for planning, project documentation and realisation of restoring and revitalising measures for the change of water regime and restoration of the Čiližský potok stream.

The collection and analysis of hydrological data included measurements of groundwater levels, surface water levels, discharges in various rainfall conditions and surveying of 63 bed profiles of the Čiližský potok stream as well as other profiles on existing drainage channels, dams and sluice gates.

For restoration of free water flow in the upper and middle section of the Čiližský potok stream, two culverts were projected at the crossing of the stream with canals as well as building a new meandering bed to connect the stream to existing canal network. To assess optimal parameters and functionality of the proposed culverts, a physical model was created in scale 1:10, on which trial measurements of different flows at the crossing with canals were performed. In a study, two problematic sections were identified as to restoration of free water flow – one in the village Pataš where the watercourse is blocked by a mass of alluvial algae trapped in reed (rkm 22.1 km) and the other one near Ižopská samota in the county of Veľký Meder where the bed was filled with a landfill consisting of industrial and domestic waste (rkm 13.1).

For restoration of water regime in a nearby wetland in Čiližská Radvaň, a reconstruction of a sluice gate on Hánsky kanál canal and building a sluice gate on Červený kanál canal was projected. By damming up the sluice gates, it will be possible to flood the whole wetland periodically once in several years.

Water level in the second wetland important for root vole next to Čiližský potok stream in cadastre of village Pataš (locality Bahno) will be regulated by an adequate water dam on the culvert at the crossing of Čiližský potok stream and Chotárny kanál canal by stop logs regulation which will enable to perform occasional floods.

A.4 Elaboration of an expert study on restoration of water regime in other selected wetlands important for root vole

Based on a mapping of the present occurrence and state of population, other localities for improvement of living conditions of root vole were selected in following Special Areas of Conservation: Dunajské trstiny, Číčovské luhy, Pohrebište, Alúvium Starej Nitry and Listové jazero.

For a planned restoration of wetlands with the occurrence of root vole, Water Research Institute conducts a study for improvement of groundwater and surface water regime in aforementioned wetlands. Using the tools of numerical modelling, various possibilities for raising groundwater and surface water level are being examined. It should be raised in a way that the building of dams and sluice gates on minor canals that are currently used for draining the wetlands will create ideal conditions for the restoration of marshes.

Restoration of the SAC Listové jazero in the cadastre of Nesvady and Vrbová nad Váhom is planned through raising the water level using water dam on Martovský kanál canal which will ensure necessary water level in Divý kanál canal to support SAC Listové jazero with water

To improve water regime in Martovská mokraď wetland it is proposed to raise water level in canal Tátoš by construction of a sluice gate.

Several options have been proposed to restore wetlands in Alúvium Starej Nitry – to open closed (filled with soil) parts of Tátoš canal and build sluice gate, to build siphon from the water stream Old Nitra and distribute water into wetlands, to fill with soil and completely close draining channels or to excavate small depressions in the places with higher underground water level and drill the impermeable layer of clay to fill wetlands.

For the improvement of water regime in Dunajské trstiny it is necessary to build regulating sluice gate on Tavarský channel draining the wetland. Similarly,  restoration of a wetland Pohrebište has been proposed – sufficient measurement will be to regulate the draining by construction of  a sluice gate.

A.5 Developing the technical documentation for restoration actions and construction of technical objects

A company dealing with projection of water management buildings has elaborated a project documentation for a planning permission and construction permit – projects of two culverts (first at the crossing of the Čiližský potok stream and Chotárny kanál canal and the second one at the crossing of the Čiližský potok stream and Vrbina-Holiare canal), a sluice gate at the beginning of Červený kanál canal. The technical documentation has been elaborated in cooperation with Water Research Institute and Slovak Water Management Enterprise, state owner enterprise, branches Šamorín and Bratislava. After obtaining construction permits, permit to work in wetland and elaborating flood plan, we finally started with revitalisation of Čiliž potok brook in the spring 2014. Nowadays, projects on other selected wetlands are being prepared. In 2015 technical documentation for restoration of wetland in SCI Dunajské trstiny was prepared.

A.6 An expert study on restoration of lowland meadows and management of bank vegetation 

The study was elaborated to map all potential localities for restoration of lowland meadows and restoration management of reed beds. It contains an assessment of the present state of the localities proposed for management, the results of phytosociological research, proposal for optimal meadow management, the most appropriate methods and models of cutting as well as the way of cutting to reintroduce reed bed management. The study concentrated on Special Areas of Conservation Čiližské močiare, Dunajské trstiny, Alúvium Starej Nitry and Číčovské luhy.

A.7 An expert study on creating habitat corridors between localities with the occurrence of root vole 

The aim of the study was to map suitable places for creating habitat corridors between areas with present and also potential occurrence of root vole populations. The purpose of planting habitat corridors is to create suitable migration routes for local populations. This will ensure connection between populations, a possibility to exchange genetic information and will enable root vole to spread to new localities. The study contains a proposal for planting habitat corridors in SAC Dunajské trstiny, Čiližské močiare (several localities on the Čiližský potok stream and localities Pataš – Bahno and Čiližská Radvaň) and in the area of the Stará Nitra (Alúvium Starej Nitry and Martovská mokraď wetland). Sites suitable for planting native trees and bushes are incorporated together with ecological demands of the species for habitat corridors as well as the optimal composition of vegetation in these corridors.