Nature Management - Habitat Restoration

Due to human activity the extension of natural habitats is decreasing all over the world. Due to the human presence lasting for thousands of years this process is in Europe even graver. The decrease in natural habitats lead to the endangerment of several species. First aim of nature conservation with habitat restorations is to raise the extension of natural habitats,  create natural ecological networks, finally preserve biodiversity.
Apart from conservation aspects economical aspects increasingly play a role. Human impacts (e.g. river regulation, mining) often have side effects (e.g. decrease in ground water level, salinization, erosion) that were not counted with at the beginning of the project. Although restoration of the original ecological state is more expensive than the project itself, it is worth to restore. Cleaner environment, natural habitats may lead to significant incomes to local people through other sections (e.g. tourism, agriculture).
 

The concept of ecological restoration was defined by the management of the Society of Ecological Restoration (SER) in 1996. According to that ecological restoration is „an activity during which the properties of an area are changed consciously with the aim of creating an ecosystem similar to the original, indigenous one” (SER 1991). Restoration is meant not only in the sense of restoring biodiversity but also typical ecological processes and structures as well as sustainable traditional routine are included.

In international and Hungarian publications (Cairns 1986, Bradshaw 1987, Cairns and Heckman 1996, Göri et al. 1994, Aronson et al 1993) several classifications of habitat restoration types can be found. Although there are differences in denomination, finally 4 main categories of habitat restoration may be distinguished.
 
In the simplest case restoration of a given area doesn’t need any intervention because due to natural succession vegetation restores itself. This is typical for forest areas where grasslands established by former cultivation disappear completely within decades without mowing or grazing.
 
Often the original vegetation can still be found upon the area but in a degraded state. In this case significant advance may be achieved by forcing back the unfavorable effects. In the case of wetlands very often just restoring the original hydrological conditions proves to be enough. This type is referred to as habitat reconstruction or in some cases habitat enhancement.
 
Often not even traces of the original vegetation can be found on the area, so practically disappeared habitats have to be restored. In the case of abandoned strip mines this process starts with the deposition of a fertile layer of soil followed by the reintroduction of microbes and gradually vascular plants. This is usually referred to as rehabilitation.
 
Finally there are cases when the original habitat cannot be restored but the creation of another near-natural habitat is possible. There are also cases when so called “good” habitats evolve due to human interference. This type is called habitat creation.

Habitat restoration have to be preceded each time by thorough surveying and planning that includes getting acquainted with the history and givens of the habitat.
During implementation first physical conditions (soil layer, water, pH, etc.) required by the habitat have to be secured. Species only may be reintroduced (if necessary) into suitable habitats.
 

Costs of restoring natural habitats may be very high. An example for this is the restoration of the Kissimmee River in Florida. The river was regulated in the 1960-s (meanders were cut, dams built) as a result of what the 103 miles long meandering river became a 56 miles long canal. Due to regulation wintering bird population dropped to 10 %, the diversity of the fish fauna decreased, the eutrification of Lake Okeechobee, into whish the river flows – a result of agriculture – accelerated. Following the recognition of the harmful effects the restoration of the river started in 1997 as a result of public pressure. The duration of restoration is estimated to be12 years. While regulation in the 60-s cost only 20 million dollars, restoration costs are estimated as high as 435 million. Despite this the Congress of the USA approved the costs, because as a result of the project flood prevention costs will be decreased, and incomes from tourism increased.

The wetland restoration of Nyirkai-Hany was realized in the South-Hanság area of the FERTŐ-HANSÁG NATIONAL PARK. The project was enabled by the support of the Hungarian Ministry of Environment and Ministry of Traffic and Water as well as the Ministry of Agriculture, Nature Conservation and Fishery of the Netherlands. The implementation was done on the part of Hungary by the Fertő-Hanság National Park Directorate while on the part of the Netherlands by the Africa, Europe, Middle East office of Wetlands International. The wetland restoration on 420 ha can be considered a pilot project, for according to the long-term concept, experiences gathered here will form the base for the restoration of other areas in the Hanság as well.

Flora and fauna of the Fertő and the Hanság are quite different despite of being connected hydrologically. Lake Fertő is a saline lake with large reed masses, saline meadows along the shores, further away xerotherm forests. Hanság is an – already dried out – sweetwater turf marsh with patches of alder marsh woods. In the remaining marshes the natural vegetation and most of the species bound to it was preserved. Waterbirds nest today in or around the reed of smaller lakes. Colonies of the Great Egret (Egretta alba) and the Purple Heron (Ardea purpurea) can be found in the reed around the lakes while the Grey Heron (A. cinerea) nests in the Csíkos Alder Wood and the Night Heron (Nycticorax nycticorax) occasionally in the willows standing near the lakes. The White-tailed Eagle that disappeared 100 years ago (Haliaëtus albicilla) and the Saker Falcon (Falco cherrug) have returned.
A rare and precious nesting bird of the Hanság reed is the Ferruginous Duck (Aythya nyroca) endangered worldwide. Its nesting is one of the aims of he restoration. Wet meadows provide nesting and feeding place for several, bird species of EU-wide importance such as the endangered Corncrake (Crex crex), the Montagu's Harrier (Circus pygargus) and the Short-eared Owl (Asio flammeus). Because practically there wasn’t left any open surface of water in the Hanság, the area hasn’t had any importance in bird migration for decades. This changerd fundamentally after flooding the restoration area.

The two basins of the Hanság – South-Hanság and North-Hanság – occupied originally an area of more than 350 km2 in the Small Hungarian Plain. The extension of the marshland often changed dramatically. Its drainage began in the 18th century, but met its aims first in second half of the 19th century. The rivers that originally spread over a wide area were given a straight bed, a several hundred km long network of channels was created. With the fall of the water level the higher lying areas being already cultivated needed irrigation. Due to the drainage of the deeper lying parts elevations are characterized presently by draught in the summer. The cessation of the continuous water coverage, cultivation of the land, mining and spontaneous oxidation of turf and unnatural forestation mainly with poplar clones have changed the overall look of the Hanság. The foundation of the Hanság Landscape Protection Area in 1976 was the first step to preserve the remnants of the natural flora and fauna of the Hanság. The national park title and the new conservation laws issued in the 1990-s finally enabled to begin to reverse the unfavorable ecological changes taken place in the last centuries.
The Fertő-Hanság National Park Directorate has restored much of the saline habitats near the Lake Fertő in the last decades with significant results. These experiences we used also in the Hanság during planning, construction and operation.

Main goals of the Hanság wetland restoration:
Creating open water surfaces upon the suitable deeper lying protected sites,
Stopping further oxidation (decomposition) of the remaining turf population,
Restoration of the marsh vegetation and water plants,
Ensuring nesting sites and undisturbed feeding places for waterbirds.Nyirkai-Hany is situated in one of the deepest lying parts of the South-Hanság. Its drainage happened relatively late, its utilization was extensive because due to lying deep, most of the year it was covered by water. The area is crossed by three significant watercourses: the Hanság-channel, the Rábca river and the Kis-metszés channel. These provide water for the restoration. Before the flooding there was no significant botanical or zoological value left, therefore the quick rise in water level could not destroy populations of protected species. The water body borders on the 286,9 ha big Bikafej Forest Reserve.
Previous to flooding the biggest part (48%) of the restoration area was dominated by Carex acutiformis and Carex riparia, besides wet (Alopecurus pratensis) and dry (Festuca rupicola) meadows (39%). To a small extent there could be found reed (4%) habitats. On 3% there were patches of wood and other habitats (4%) like farmlands. Of the protected Cirsium brachicephalum we found several tens of thousands, upon the disturbed elevations weedy patches grown over with the invasive Giant Goldenrod (Solidago gigantea). The wild boars (Sus scrofa) inhabiting the surrounding forests contributed to the change of the grassland on these patches. Soil of the Nyirkai-Hany is decomposed turf. Below the turf layer there lies a watertight layer of clay. The conservation aims were set by the Fertő-Hanság National Park Directorate. The plans for realization were prepared by the company Control Bau Kft. Beside the ecological aims a main aspect was that the landowners of unprotected areas don’t experience negative effects of the restoration – mainly inland waters. Besides, the flooded areas of the restoration could play a future role in the protection against floods.
The works started in the beginning of 2000. Two parts were flooded on 15th March and 3rd April 2001. Earth works were continued in autumn that year, the third part was flooded on 20th October 2001, at this time the area was surrendered officially.
Sluices and dams were created during implementation, water plants deriving from Hanság habitats and indigenous fish species were introduced.

To test the effects and results of the habitat restoration a monitoring program was started in which the change in the chemical parameters of the water, the succession of the vegetation and the effects on the bird population are recorded. Main participants of the monitoring program are the Hungarian Academy of Sciences, the Szeged University of Science and the Fertő-Hanság National Park Directorate.

Changes in the vegetation
The vegetation evolved after the flooding may be categorized. Some groups occur as clean populations others are rather a transition between main vegetation classes.

Sedge (Carex): Carex acutiformis and Carex riparia dominated habitat of closed vegetation, with occasional other species (Iris pseudachorus, Sparganium erectum, Lythrum salicaria) At some places it creates mosaic populations with bulrush and open water. Sedges covered great areas on all three parts but during the 8 years since flooding their population has gradually decreased. The decrease is most conspicuous in the “Liliomos” (Lily) area where the sedges practically totally have disappeared.
Bulrush (Typha): Closed and lightly dispersed populations dominated by Typha angustifolia and Typha latifolia. Among them there grow typically single stands of Alisma plantago-aquatica, Carex acutiformis, Lycopus europaeus. On some places it creates mosaic populations with sedges and tang vegetation. Previous to flooding bulrush populations were not considerable in the area, since then they are continually spreading. Great, closed bulrush patches evolved in the so-called “Bikafej” (Bullhead) area while in the “Lilomos” area rather dispersed bulrush is typical.
Sweet-grass (Glyceria): Glyceria maxima dominated populations with occasional Carex riparia, Typha angustifolia, Typha latifolia stands. Beneath them tang made up of Lemna minor and Spirodela polyrhiza is typical. Their populations gradually decrease in the area. At the end of 2005 populations remained only in the area „Nyugati-Mór rétek” (Western Moor Meadows) and beside the dams.
Reed (Phragmites): Phragmites australis dominated closed and dispersed reedy populations. On some places two levels are present, the lower made up of Carex acutiformis and Carex riparia. Besides, some stands of Typha angustifolia, Typha latifolia, Sparganium erectum and Solanum dulcamara occur. Reed populations are expanding in the area.
Phalaris: Habitats made up of Phalaris arundinacea with little diversity. In areas temporarily covered by water they mingle with sedge and bulrush populations.
Open water: Areas without or with few (1-2%) vegetation. Their extent is growing continually on the area.
Tang vegetation: One- or two-level habitats dominated by tang species. Characteristic, common species are Ceratophyllum demersum, Myriophyllum spicatum, Najas marina, Persicaria amphibia, Lemna minor and Utricularia vulgaris. Their populations are expanding in the whole area continually.
Other vegetation: This category includes non-marsh habitats. These are for example habitats of dry places (islands, dams). Natural grasslands are dominated by Alopecurus pratensis, Festuca arundinacea and Festuca rupicola, but weedy habitats dominated by Calamagrostis epigeios, Solidago gigantea and Echinochloa oryzoides also occur.In the first year after flooding (in 2001 on the areas „Liliomos” and „Bikafej”, in 2002 on „Nyugati-Mór-rétek”) species intolerant to continuous or temporary water coverage quickly disappeared. Vegetation classified as “other” remained practically only on dry places. An exception was only the Wood Small-reed (Calamagrostis epigeios) that remained on places with temporary, shallow water coverage.
Sedge communities (Carex) tolerated in the first two years high water coverage, but completely disappeared in the third year from deepwater places. In shallow water they are continually expanding and on several dry places they grow as well. On former plough-lands they compete with bulrush, slowly displacing it.
Bulrush populations (Typha) were expanding after flooding, especially in shallow water, and created in the second year already dense, closed populations. Expansion may be witnessed also in mid and deep water, here dispersed occurrence is characteristic rather.
Sweet-grass populations (Glyceria) were present prior flooding in the deepest parts. Their presence declined sharply in the second year.
Populations of reed (Phragmites) are dying off where they occurred prior to flooding but spread in shallow and middle water.
Phalaris tolerated in the first year water coverage but from the second year on were decreasing and in the fifth year disappeared from the area.
Open water patches are expanding continually, mainly on the former habitats of sedge and sweet-grass populations.
The newly appearing tang populations are expanding as well in all water depths. In the first two years mainly Myriophyllum spicatum, Ceratophyllum demersum and Persicaria amhipbia dominated, but in the third year Utricularia vulgaris also appeared. Latter species forms at some places great populations several hectares wide. Najas marina is spreading as well. In the beginning it appears as a second level, mainly beneath Myriophyllum spicatum és and Ceratophyllum demersum, but later often displaces them.

Breeding of waterbird species was in the beginning limited due to scarce vegetation, but with the spreading of bulrush and reed in the second year of flooding the conditions became better. Species breeding in colonies upon trees or on islands are present from the beginning on. On the breeding island created for this purpose nest more than thousand pairs of Black-headed Gulls (Larus ridibundus) as well as some pairs of Mediterranean Gulls (Larus melanocephalus) and Common Terns (Sterna hirundo). On the great poplars left colonies of cormorants (Phalacrocorax carbo), on the bush willows Night Herons (Nycticorax nycticorax) nest. In 2006 we found nesting Little Egrets (Egretta garzetta) for the first time. Their close relatives, Great Egrets (Egretta alba) nest in reedy patches, Purple Herons (Ardea purpurea) in the reed and bulrush, forming loose colonies. From 2005 on the strictly protected Spoonbill (Platalea leucorodia) nests here as well. Conditions only slowly arose for the birds nesting in water vegetation. Against all expectations no colonies of the Black-necked Grebe (Podiceps nigricollis) or terns (Chlidonias sp.) evolved. In the beginning, when places without vegetation were abundant (dams, nesting islands, etc.) species preferring such habitats settled, such as the Avocet (Recurvirostra avosetta), the Black-winged Stilt (Himantopus himantopus) and the Little ringed Plover (Charadrius dubius). With the expansion of vegetation these vanished quickly.
Te population changes of frequent birds are more difficult to investigate. On an area 33,5 ha big we found 175 coot (Fulica atra) nests in 2002, that projected a coot density of 5,22 pairs/ha.
According to a detailed survey done 2002 nine of the species present in the area may be told persistent, being present at the time of ice-coverage as well. Further nine species occur occasionally (less than 10 observations). Dominant species according to numbers of individuals are the Mallard (Anas platyrhynchos), the Coot (Fulica atra) and the Greylag Goose (Anser anser), latter was formerly observed only occasionally in the Hanság.
Of the species building their nests in the vegetation characteristic species are the Little Grebe (Podiceps ruficollis), the Great Crested Grebe (Podiceps cristatus), the Ferruginous Duck (Aythya nyroca) and the Common Pochard (Aythya ferina). The Bitterns (Botaurus stellaris) and the March Harrier (Circus aeruginosus) are present with a few nesting pairs. The quick settling of the Red-crested Pochard (Netta rufina) is noteworthy, being an extremely rare breeding bird in the country except on the Lake Fertő.
The number of species was higher during spring migration from the end of April to the end of June. In this period 30-40 species were present with a peak (40) in the first week of May. In autumn the number of species was only half of this.
The maximum number of individuals observed at a time was also highest in spring, from the end of March to the middle of April it regularly exceeded 3000. Total numbers of individuals counted in the summer and autumn didn’t even get near that. It has to be mentioned that in 2002 there was no significant migration of wild geese in the area, in the following years the total number of wild geese counted in October and November was several thousands.
A joint Hungarian-Austrian project monitors the regional migration of wild goose species that was expanded to the Nyirkai-Hany area. It showed that the number of geese – Greylag Goose (Anser anser), Greater White-fronted Goose (Anser albifrons) and Bean Goose (Anser fabalis) – grew over the years, meaning that a new resting place evolved in the Kisalföld region. The Barnacle Goose (Branta leucopsis), the Red-breasted Goose (Branta ruficollis) and the endangered Lesser White-fronted Goose (Anser erythropus) were observed several times as well.
The number of shorebird species and individuals was low, explained by the relatively deep water. In the time of spring migration the Lapwing (Vanellus vanellus) and the Ruff (Philomachus pugnax) dominate, other Limicoles appear occasionally. In 2001, the first year of flooding the Greenshank (Tringa nebularia) appeared in unusually high numbers (max. 54 individuals), later this was not noted. A greater flocking of shorebirds may only be expected at a low water level in the future.

Among the rare species (from a Hungarian point of view) the Pygmy Cormorant (Phalacrocorax pygmeus) has to be emphasised. For the first time it was observed in winter 2001-2002, and appears in small numbers regularly in this time of year. The Red-breasted Merganser (Mergus serrator), the Great Snipe (Gallinago media) and the Little Tern (Sterna albifrons) were sighted as well.

On the long term we expect on the restoration site changes according to the goals set. Presently we are witnessing a quick succession process resulting in a rapid change of the vegetation. The area of greater reed patches mixed with bulrush and sedge is growing, on the remaining open water surfaces floating and rooted tang is evolving. The changes in vegetation structure reflect in the quick change of bird populations. In the past eight years the Nyirkai-Hany became one of the main migration sites of Western Transdanubium for waterbirds.
Within the wetland reconstruction program of the Hanság the directory of the Fertő-Hanság National Park plans further floodings with the same goals as in the case of Nyirkai-Hany. The next step is the re-flooding of Osli-Hany, an area of 1322 ha.

The whole area of the wetland restoration may be visited to a limited extent. To know more about the possibilities of visiting and how to get there please write to fhnpiinfo@fhnp.kvvm-hu .