Flora and vegetation complexes

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Published on Tuesday, 15 November 2011 15:28

The area of the Słowiński National Park is characterised by large biodiversity of habitats which, together with the complicated soil water regimes and local climate features, constitute the direct basis for the specific and high biodiversity of its vegetation.

Currently, the Park’s flora includes: 911 species of vascular plants and 165 species of bryophytes. One also finds here around 300 species of algae, 424 species of fungi, and 225 species of lichens. Sea climate in this part of Poland with relatively cool summers and mild winters creates favourable conditions for plants of Western (Atlantic) type of range (distribution), including, inter alia, hydrophytes – shore plantain Litorella uniflora and water milfoil Myriophyllum alternifolium, mire plants – spoon-leaf sundew Drosera intermedia,  cross-leaved heath Erica tetralix, dune plants - sand sedge Carex arenaria, shepherd's cress Teesdalea nudicaulis, and, from shrubbery and forest plants - Bog Myrtle Myrica gale and common honeysuckle Lonicera periclymenum. Another distinguishing group includes species of North-Western (boreal) type of range (distribution) such as: knoutberry Rubus chamaemorus, black crowberry Empetrum nigrum, and twinflower Linnea borealis. These plants, typical for tundra, came to Pomerania at the end of the last glacial period and today they are regarded as glacial relicts. Moreover, there are some warm house species of Southern range type represented e.g. by sand pink Dianthus arenarius.

Among vascular plants in the Park currently 46 species are under strict protection, and 14 species under partial protection. Protected species include spermatophytes and cryptogams. Among the former the prevailing group are plants of water and mire habitats, such as common eelgrass Zostera marina, pond water crowfoot Batrachium peltatum, bladderworts Utricularia spp., Marsh Helleborine Epipactis palustris, and Jacob’s ladder Polemonium caeruleum. What is more, forest habitat species also constitute large groups of protected species, including: orchids - creeping lady's tresses Goodyera repens, lesser twayblade Listera cordata, lesser butterfly-orchid Platanthera bifolia, mezereon Daphne mezereum, and Marsh Labrador tea Ledum palustre. Among protected cryptogams one finds four species of fern, including royal fern Osmunda regalis, and four species of lycopods with very rare northern bog club moss Lycopodiella inundata at Wild Fields.

Among bryophytes 36 species are under strict protection and 20 under partial protection; sphagnum prevail Sphagnum spp. – mosses of bogs and transitional mires. Moreover, 10 species of fungi are covered by strict protection. Another large protected group are lichens - 48 and 9 species under strict and partial protection respectively. In the Park there are also in abundance of arboreal lichen of tree moss/beard lichen genus Usnea spp. and Ramalina spp., and on dune sands - of cup lichen genus Cladonia spp. and Cetraria spp. One should also mention protected algae at the Sea bottom; bladder wrack Fucus vesiculosus (brown algae) and Black Carrageen Furcellaria fastigiata (red algae).

The 32-km long Łeba Spit is characterised by sea plant community. On this relatively narrow patch of sandy land clear zone formation was preserved. It begins at the inland beach hinterland away from storm surge range where an ephemeral, narrow zone of pioneering dune communities of halophytes - European searocket Cacile maritima and sea sandwort Honkenia peploides – appears. Beyond within the scope of front dunes communities of white dunes develop. Their patches are formed by fields of long grasses: prevailing European beachgrass Ammophila arenaria accompanied now and then by sea lime grass Honkenia peploides. White dune communities are optimum habitat for two rare protected species: sea holly Eryngium maritimum and Linaria loeselii. Further in the land a grey dune zone takes form of short psammophilic grasses (from small cluster grass – grey hair-grass Corynephorus canescens), typically with other spermatophytes and well-developed ground layer of mosses and lichens. And, further from the sea there is a forest zone with various forms of sea pine forests. Deep in the Spit in forest zone and moving dune zone many unique hygrophyte communities develop in pits between dunes. These phytocoenoses are habitats for such interesting species as: English sundew Drosera anglica, spoon-leaf sundew, mire spike-mosses, cross-leaved heath, and Bog Myrtle.

The Spit separates Gardno-Łebsko Lowland, established during the last glacial period, from the Sea. Its landscape is dominated by the two Park’s largest lakes: Gardno and Łebsko. Open area of these eutrophic lakes is a habitat for hydrophytes of large, swimming leaves - European White Waterlily Nymphaea alba and Yellow Waterlily Nuphar luteum. In the water deep water-milfoils and pondweeds build their communities – mostly clasping-leaf pondweedPotamogeton perfoliatus. At lakes’ shallows there are quite numerous communities of common clubrush Scirpus lacustris of various sizes, and along shore there is a wide belt of common reed beds Phragmites australis. High level of groundwater at land habitats and polders by the lakes creates excellent conditions for reed bed forms of low mire. There are 16 types of such communities, and the most common ones are reed beds of: acute sedge Carex acuta, brown sedge Carex disticha, and reed canarygrass Phalaris arundinacea. Boggy slope of the Lowland, located in mire-meadow plant complexes, where low-fertility waters, mostly from precipitations (communities resembling oligotrophic ones), are covered by transitional mire communities.

One finds here many phytocoenoses of sedge swamps, sometimes of rich species composition, as well as high bogs with common cottonsedge Eriophorum angustifolium and bottle sedge Carex rostrata. Less (seasonally) damp and medium damp (fresh) habitats in these complexes are covered by meadow plants. The most common meadow communities of the Lowland and in the Łeba and Łupawa valleys are meadows with prevailing soft rush Juncus effusus and meadows with prevailing tufted hair-grass Deschampsia caespitosa. There are also many patches of meadow plants of relatively small sizes with meadowsweet Filipendula ulmaria, purple loosestrife Lythrum salicaria and garden yellow loosestrife Lysimachia vulgaris. However, patches of fertile moor grass meadows and the so-called “orchid meadows” are rather rare. Enclaves of oatgrass meadows, as well as inland moors and psammophilic grasses with sea thrift Armeria elongata and maiden pink Dianthus deltoides are not so common; they are met in the Gardno Lake neighbourhood where they develop on naturally shaped, mineral old lake berms. They constitute clear “beds” lifted up above the level of surrounding meadows and fens. Moreover, complexes of halophytes, rare in Poland therefore so interesting, are also of meadow nature. Such phytocoenoses were developed near the north-western Gardno Lake shore and the south-eastern Łebsko Lake shore. Their location seems to be related with close neighbourhood of sea waters poured in both lakes’ basins during storms. Oligophagic and acidic (pH<5) complexes depend only on precipitations and are found among bog plant communities. Large bogs areas can be found in Kluki and Żarnowska Protection Districts, south from Łebsko Lake. These highly-specialised complexes take form of undershrub formations, very rare in Poland, with cross-leaved heath, or swamp forests – here established in regional variant with bog myrtle bushes in understory.

The Parks’ forest phytocoenoses cover the following forest complexes: birch woods, alder woods, riparian forests, oak-hornbeam forests, beech woods, birch-oak forests, and sea coastal and inland pine forests. Large areas of the Spit are currently covered by pine forests specific for seacoasts called crowberry forests (due to black crowberry, an undershrub in groundcover). Although these forests were mostly plantations, they are regarded as natural complexes or close to natural complexes.

The Park’s forest areas cover also planted mountain pine Pinus mugo and black pine Pinus nigra in the Spit and tree stands introduced beyond the Spit on post-agricultural complexes. The group of deciduous trees living on permanently boggy, mire habitats comprises two forms of alder woods: Sphagno squarrosi-Alnetum and Ribeso nigri-Alnetum, with black alder Alnus glutinosa, and bog-rich forests with moor birch and Scots pine. The most fecund, damp forest habitats are covered with enclaves of alder-ash and oak-ash riparian forests. Damp, but also acidophilus substratum is characteristic for birch-oak woods of specific range limited only to coastal zones. Mesophile oak-hornbeam forests are rare and only fragmentary developed in the Park. Sandy and loamy sand oligophagic habitats in Gardno-Łeba Lowlands and Rowokół Massif are covered currently by most off all patches of pine forests mixed with enclaves of acidophil birch-oak woods and beechwood forests. At the end of this short summary of the Słowiński National Park plant communities, one should mention shrubby vegetation, including most of all common formations of willow tree shrubberies, mostly Salicetum pentandro-cinereae with prevailing grey willow Salix cinerea, developed among complexes of fen-mire-meadow vegetation. In the Park one can also meet interesting enclaves of shrubberies limited only to coastal zones with eared willow Salix aurita and bog myrtle. They develop in old, permanently damp deflation pits of the Łeba Spit, and peripheries of transitional mires, mostly in the so-called “Ciemińskie Swamps”, south-west from Kluki.