Amalva wetland is dominated by mire that used to cover 3.414 ha and was formed of raised bog (47%), transition mire (9%) and fen (44%). During the XXth century more than half of the area (2.159 ha) was drained for forestry and agriculture. Three hydrologically different parts could be distinguished in the area:
1) Botanical reserve (1.479 ha) - directly not drained area, but identified as degrading due to surrounding drainage systems: polderized north-eastern part, drained southern part and arterial drainage ditch dug along the western edge thus channelizing water from the former lag zone;
2) Polderized North-eastern part (638 ha). Hydrological regime in the polder was partly renaturalized during previous WETLIFE project to ensure the best possible compromise between nature conservation and extensive land use (grassland management);
3) Southern drained part of Amalva mire (1521 ha). Drainage ditches were blocked in 260 ha during previous WETLIFE project.
The medium thickness of the peat in the not drained part of the raised bog is 2,19 m and reaches up to 5,6 meters in deepest places. There is a deep sapropel layer (up to 5,6 m) below the peat layer (Lithuanian peatland cadastre, 1995). Below the sapropel layer there is till with lenses of sand.
In the North-eastern part of the mire there is 193 ha hypertrophic Amalvas Lake - a remnant of former postglacial lake. The average depth of the lake – 1 m, the maximum depth – 2,9 m, average mud layer – 2 m. The Šlavanta stream falls into the lake and the Amalvė stream outflows from it. The whole wetland belongs to the Dovinė river catchment area (589 km2). Ringovėlė and Bebriūtė rivulets that used to bring water to the western and northern parts of the lag zone of Amalva bog currently discharge into surrounding drainage ditches. Only 18 % (9,9 km) of streams are natural in the area. The rest 46,1 km are melioration ditches or straitened streams.
Degraded raised bog occupies the biggest area of Amalvas wetland complex (1.159 ha). Central and eastern parts of remaining not drained raised bog are characterized by having more favourable status. Less trees and scrubs are found there. Coverage of scrubs and grasses can reach up to 40 %, while mosses form almost continuous cover (95%). Sphagnetum magellanici communities are common. Calluna vulgaris dominates among scrubs. Oxycoccus palustris is less abundant while other species (i.e. Chamaedaphne calyculata, Ledum palustre, Empetrum nigrum, Andromeda polifolia) are infrequent. Eriophorum vaginatum and even more hydrophilic plants, such as Drosera rotundifolia can be found there. Sphagnum mosses are typical to Oxycocco–Sphagnetea plant communities: predominate Sphagnum fuscum and S. magellanicum, S. rubellum, not so abundantly found –Polytrichum strictum. The periphery of degraded bog is the most influenced by drainage, especially the southern part. The plant cover there is formed by the broad range of bog plant species, however the total composition of species and quantitative ratio of plants are not typical for raised bog habitats. Coverage of shrubs is very dense (up till 90 %). Calluna vulgaris and Ledum palustre dominate, while Andromeda polifolia and Vaccinium uliginosum are quite common. Moss coverage is not continuous (~80 %) and green mosses are quite abundant. Sphagnum capillifolium and S. angustifolium are the most abundant species among peat-mosses, while typical to raised bogs S. magellanicum is rare. Abundance of Cladonia lichens, forest scrub species Vaccinium vitis-idaea and Pleurozium schreberi mosses in drained areas are all signs of dryness.
Ledo–Pinetum sylvestris communities occur in bog woodland located east of Amalva river. The composition of grass, scrub and moss species is close to natural communities. Ledum palustre, Oxycoccus palustris and Eriophorum vaginatum predominate there along with not so abundant Chamaedaphne calyculata, Vaccinium uliginosum, Andromeda polifolia, Drosera rotundifolia. Sphagnum magellanicum and S. fallax predominate among mosses. The presence of hydrophilic species such as Drosera rotundifolia and Sphagnum fallax shows relatively good status of communities. However, abundance of Ledum palustre, relatively high density (projection cover up till 70 %) of intensively growing pine and especially birch Betula pubescens trees, exhibit influence of drainage. The anthropogenic influence notably occurs closer to ditches, where extensive cover of trees, degraded moss cover, flourishing scrubs (Ledum palsutre, Vaccinium uliginosum, Vaccinium myrtillus) exhibit altered hydrological conditions.
Transition mires surround Amalvas Lake from the western and southern sides and are formed in the Valley of Amalvė River. Caricion lasiocarpae communities prevail there. The structure of plant communities as well as their status differs around the lake and along the river valley. Single trees (Alnus glutinosa) with scrubs grow around the lake (projection cover reaches 30%). The grass layer is quite sparse (projection cover up till 60%). Carex lasiocarpa species prevails. Fen species - C. lepidocarpa also occurs because of quite high pH value (7.4). The projection coverage of mosses reaches 30 %, and is characterized by inconsiderable number of species. Calliergonella cuspidata with Campylium polygamum predominates there. The flora composition of plant communities surrounding the lake is similar to undisturbed communities. The transition mire of Amalvė valley is characterized by the abundance of birch and alder (projection coverage 20%) and shrubs (projection coverage 20%). Grass layer is very dense (projection coverage 80 %) and rich in species with especially dense higher hygrophytes and helophytes. Thelypteris palustris, Carex lasiocarpa, Lysimachia vulgaris and Phragmites australis prevail in grass layer, Carex appropinquata, C. disticha, Peucedanum palustre, Valeriana officinalis grow abundantly as well. Species are typical of transition mires, alkaline fens and flooded meadows. The cover of mosses is not dense (projection cover 30%), consisting of spare species of mosses. The prevailing species is Calliergonella cuspidata, with a few of Fissidens adianthoides, Plagiomnium ellipticum occurring there. The abundance of intensively growing trees, shrubs and reeds indicate the intensive vegetation succession and low stability of plant communities.
Fennoscandian deciduous swamp woods are concentrated in the south-eastern part of Amalvas botanical–zoological reserve. They surround bog woodland by narrow zone, and interfere with the transition mire, borders with Amalvė River in the southern part of the reserve. Habitats’ vegetation evolved from the transition mires communities, thus most of the herbaceous plants, scrubs and mosses species occurring are more common for the transition mires.
One Red Data book plant species (Dactylorhiza incarnata) is registered in the area.
Alien invasive Sosnowsky's Hogweed (Heracleum sosnowskyi) is rapidly spreading in the Amalva wetland along several ditches.
Fish fauna is not diverse. 11 species are found in the lake and Amalvė river. All species are insensitive to environmental conditions predetermined by high trophic state of water bodies.
Bird fauna is represented by species typical of bog woodland and transition mires (in the botanical reserve), as well as meadow and fen. Typical open bog breeding species, such as dunlin (Calidris alpina) and curlew (Numenius arquata) have disappeared due to increased cover of trees. However, the area remains important breeding site for black grouse (Tetrao tetrix). Bushy transition mire areas serve as important breeding sites for bluethroat (Luscinia svecica), while certain fen areas - for spotted crake (Porzana porzana). Since the WETLIFE project Amalvas polder become an important resting site for migratory birds during spring migrations. Polder is increasingly important for corncrake (Crex crex), lapwing (Vanellus vanellus) and has a potential to become a breeding site for such rare birds as dunlin (Calidris alpina), ruff (Philomachus pugnax) and even great snipe (Galinago media) if proper management of the area is carried out.
Amalva area is also used by wolves, moose. Otters live in Amalvė river. High number of foxes, as well as alien racoon dogs and Canadian minks is an important threat to avian fauna in the area.
Close neighbourhood (less than 2 km) of Žuvintas wetland makes it the biggest wetland complex in the country (more than 10.000 ha), enables easy migration of species and increases resilience to climatic and other challenges.
Current most important biodiversity values in the Amalva area are as follows (see maps: "Natura 2000 habitats and bird species in the Amalva project site"):
Habitats of Community importance:
7120 degraded raised bog habitat constitutes 1.158 ha, being the biggest degraded bog area still capable to regenerate in the country;
91D0* Bog woodland (104 ha)
7140 Transition mires and quaking bogs (106 ha);
9080* Fennoscandian deciduous swamp woods (91 ha).
Otter (Lutra lutra) - the only species found in the area protected under habitat directive (2-3 animals).
Birds of Community importance:
Black grouse (Tetrao tetrix) (up to 20 singing males) (0,6%-1% of Lithuanian population);
Bluethroat (Luscinia svecica) (up to 7 pairs) (3.5%-7 % of Lithuanian population);
Spotted crake (Porzana porzana) (up to 10 pairs) (0,7-1 % of Lithuanian population);
Corncrake (Crex crex) (up to 65 singing mails) (0,21-0,26 % of Lithuanian population, biggest concentration in the whole Žuvintas biosphere reserve);
Polderised northern part of Amalva wetland (638 ha) has become an important site for migratory birds during spring migrations, since WETLIFE project (finalised in 2012) carried out restoration of hydrological conditions in the area. In total 35 bird species were registered in 2011 (first year of nature-friendly water management in the polder) dominated by white-fronted goose (1450 individuals) and bean goose (1000 ind.). Abundant ducks (9 species), dominated by wigeon, mallard and tufted duck; waders (13 species), dominated by ruff , lapwing, wood sandpiper and golden plover . Number of breeding waders and corncrakes has increased as well.
Altered hydrology is the main threat to habitats targeted by the project
The Amalvas wetland complex was strongly influenced by human activities. Land reclamation carried out in the second half of the XXth century resulted in the drained area covering 2.160 ha, i.e. more than half of the wetland area.
Northern part of the Amalva wetland (former fen and transitional bog) was transformed into winter polder (638 ha) with meadows and pastures. Ground water level in the polder was lowered by more than 2.0 m, what in turn affected water level in the neighbouring bog area despite of installed protective dike. Southern part (~1520 ha) was intersected with drainage channels. Approximately half of it (former fen, swamp woods, transitional mire) is currently used for agriculture. Second half (degraded raised bog and swamp woods area) - managed as forest land. The dike and the sluice-gate on the outflow from Amalvas Lake were built in the south-eastern part of the wetland in order to stop water-flow from the remnant of the Amalva wetland to the newly established agricultural areas. Deep magistral drainage ditch was also dug in the lag zone along the western edge of the bog eliminating transitional wet habitats and significantly increasing surface and subsurface water runoff from the bog. Several small ditches were dug further into the bog in order to facilitate water runoff to the magistral ditch.
The above mentioned hydrological alterations led to development of 1.158 ha of 7120 Degraded raised bog habitat with significantly reduced capacities to provide former ecosystem services, with mineralizing peat, increasing cover of birch trees, heath and wild rosemary and decreasing cover of Sphagnum mosses. Habitat changes resulted in complete loss of typical open bog bird species, such as golden plover, curlew and wood sandpiper.
Significant improvement of hydrological conditions was achieved by the previous WETLIFE project, which: 1) minimised drainage impact of the Amalvas polder in the north; 2) restored water level in the south-eastern part by reconstructing protective dike and the sluice gate on Amalve river; 3) restored water level in the south by cutting trees and completely blocking drainage ditches in 210 ha of former bog. The most important remaining threat to recovery of the Amalva bog is the 4,9 km magistral ditch dug in the lag zone along the western edge. Other problems related to hydrological condition: 1. water runoff through the western edge (1,5 km) of restored southern part of the bog. Ground water level failed to recover approximately 200-250 m from the edge after blocking of the drainage channels, as water level in the neighbouring drained agricultural fields is approximately 2 meters lower than in the raised bog. Due to drainage the bog subsided and developed a slope towards the edge, thus significantly increasing surface water runoff. Significantly lower porosity of the surface peat layer and increased subsurface drainage due to rooting of trees further worsened the situation; 2. Loose section (~100 m) of the south-eastern dike due to underground charred peat (result of former underground peat fire) and increased pressure from high water level in the endiked area.
Climate change already has an impact on bogs in Lithuania due to increasing temperatures (and evaporation) and slightly decreasing precipitation during the vegetation period. Quite significant increase in precipitation during the cold season has no important role to play. Currently this trend is slightly more prominent in the southern Lithuania where Amalva bog is located, however the difference between precipitation and evaporation during the vegetation period is still more than 250 mm - a threshold for raised bog development. In the context of such climate trend restoration of proper hydrological conditions in the bogs is even more important for increasing resilience.
The main actions include:
- Elimination of draining impact of melioration systems along the 4,9 km western edge and 0,78 km south-western edge of Amalva bog by blocking magistral melioration ditch, readjusting underground melioration system and building endikement. Land purchase and one-off compensation payments will be necessary to complete the action;
- Removal of woody vegetation in part of Amalva bog;
- Supporting grassland management by introducing beef cattle for wet meadow and fen management, assisting with grassland management expertise and facilitating restoration of grasslands in cultivated peatland areas;
- Organising public events and development and publishing of information material presenting wide spectrum of peatland ecosystem functions and their economic and intrinsic value for policy makers and wider public.