Sand dune - Country Report, Latvia

Latvia

Author: Dr J Patrick Doody, new 2007; additional information Bird (The World’s Coasts: Online)

INTRODUCTION

Extensive sand dunes occur along the coast of Latvia in the southern Baltic. Typically, they are up to 2.5m high, but where sand accretion is rapid, as on the southern shore of the Gulf of Riga, they may attain a height of 6m. Here, along a 56km stretch of coastline, about 50,000 cu. m/year of sand is transported by onshore winds from the beach to the foredune (Ulsts 1998).These have developed since the middle of the Holocene and have been extensively modified by man over the last 2,000 years.

DISTRIBUTION AND TYPE OF DUNE

The Litorina transgression influenced coastal evolution in the eastern Baltic area and the ensuing regression (7,000-2,800 years ago). During the regression sand, gravel and boulders on the emerging sea floor were shaped into beaches, beach ridges and dunes by wave and wind action (Gudelis 1967), forming a modern depositional terrace up to 10km wide. Behind the sandy beaches, there are often older parallel foredunes and newer parabolic and active dunes (Eberhards 1998), the older ridges to landward having been raised by postglacial isostatic movements. The south coast, from the River Gauja to the River Lielupe, is a sandy depositional coast with beaches 30-50m wide and foredunes up to 6m high, behind which are dune ridges up to 20-30m high, some bearing pine forest while others have drifted inland during recent centuries. The dune sand partly derives by longshore drifting from the eastern and western shores of the Gulf of Riga and partly from the Rivers Daugava and Gauja. Between the seaside resorts of Jurmala and Engure coastal dunes have been eroded, mainly during the severe storm of 1969. The dunes along the Latvian coast stretch inland initially as low embryonic dunes with scattered vegetation. Higher foredunes and then grey dunes typically come next. ‘Black dunes’ covered by forest represent the final stage of stabilisation. Not all stages of dune development occur at all sites especially where abrasion causes erosion of the foredunes.

In Latvia, the total length of primary dunes reaches about 240km along the coast.

VEGETATION

The following EU Habitat Directive communities occur in Latvia. Strandline, 2110 Embryonic shifting dunes. Embryonic dunes are the first stage of dune development. They are small, about 10-50cm high sandy bars with sparse vegetation of halophylous plant species such as Leymus arenarius‚ Honckenya peploides‚ Calammophila baltica‚ Elytrigia littorea. Rare plant species in embryonic dunes include Elytrigia junceiformis‚ Linaria loeselii and Crambe maritima.

Foredune

2120 Shifting dunes along the shoreline with Ammophila arenaria (‘white dunes’). Foredunes develop behind embryonic dunes. As with embryonic dunes, the habitat is dynamic and can include areas of bare sand. The vegetation is sparse or scattered, with species of sandy habitats. Typical plant species of foredunes are: Ammophila arenaria‚ Calamagrostis epigejos‚ Leymus arenarius‚ Festuca arenaria‚ Hieracium umbellate and Artemisia campestris. Rare plant species include Eryngium maritimum‚ Lathyrus maritimus‚ Linaria loeselii and Tragopogon heterospermus. Shrub species may also be found growing in foredunes. These are mostly planted to aid stabilisation and include Salix daphnoides‚ S. viminalii and S. rosmarinifolia. Rare plant species such as native Salix repens and Lonicera caerulea var. pallasii also occur.

Acid dune grassland

2130* Fixed coastal dunes with herbaceous vegetation (‘grey dunes’). Grey dunes represent the next stage of development. Grey dunes are relatively stable. There are two types of grey dunes in Latvia – grey dunes with low vascular plant vegetation and grey dunes with shrubs and trees. The former consist mainly of bryophytes, lichens and low perennial plants. Typical plant species are Koeleria glauca‚ Carex arenaria‚ Thymus serpyllum and Pulsatilla pratensis, as well as bryophytes, such as Racomitrium canescens and Tortula ruralis. Rare plant species Alyssum gmelinii‚ Dianthus arenarius and Silene borysthenica are also present. The latter include individual or groups of trees‚ shrubs or their groups. In some places, groups of dwarf shrubs develop. Typical scrub species are Juniperus communis‚ Pinus sylvestris‚ Salix daphnoides and rare species include Lonicera caerulea var. pallasii and Salix repens. Dune slack, 2190 Humid dune slacks 2170 Dunes with Salix repens ssp. argentea (Salicion arenariae). Between dunes, dune slacks (starpkāpu ieplakas in Latvian) can be located. Dune slacks are characteristic of depressions between lines of dunes lying parallel to the coast. They are usually narrow and can change rapidly as they become invaded by shrubs and trees. There are several types of dune slacks: Dune slacks with pioneer vegetation are located in periodically moist depressions with scarce or continuous plant cover formed by pioneer species. Typical plant species are Sagina nodosa‚ Equisetum variegatum‚ Carex flacca and rare species such as Centaurium littorale and Juncus balticus. Dune slacks with grassland vegetation occur in depressions in a transition zone between foredunes, grey dunes and shrub zone or forest. In the plant cover, grassland species dominate typically with species including Rhinanthus vernalis‚ Poa pratensis‚ Anthoxanthum odoratum‚ Ranunculus acris and rare plants such as Dactylorhiza incarnata‚ D. baltica and Epipactis palustris. In very wet sites, dune slacks with calcareous fen vegetation occur. These are depressions where calcareous fen species are characteristic. There is little or no peat and typical plant species include Carex flacca‚ Potentilla erecta‚ Molinia caerulea‚ Galium boreale and rare plants such as Schoenus ferrugineus‚ Cladium mariscus and Primula farinosa. Dune heath. 2140* Decalcified fixed dunes with Empetrum nigrum. Woodland. 2180 Wooded dunes of the Atlantic, Continental and Boreal region. Inland dunes 2320 Dry sand heaths with Calluna and Empetrum nigrum. 2330 Inland dunes with open Corynephorus and Agrostis grasslands.

IMPORTANT SITES The west coast of the Gulf of Riga has sandy beaches 20-50m wide and parallel dune ridges (Eberhards 1998). The sandy coast curves out at the northern end to Cape Kolka, a large sandy foreland with about 200 parallel dune ridges, formed as a result of accretion of sand delivered by longshore drift from the south. Some of the ridges have been disrupted by blowouts, and there are complex parabolic dunes. Towards the Lithuanian border is a major complex dune ridge up to 34m high, formed during the Litorina Sea stage. Near Cape Bernati and Cape Mietrags there has been increased erosion of the beach and dune coast during the last few decades. CONSERVATION. The sand dunes are affected by a variety of human activities. These include the following threats: Threat 1: Deterioration of coastal ecosystem by motorised vehicles; Threat 2: degradation of coastal natural habitats by recreation and activities of tourism; Threat 3: Destroying of indigenous flora and vegetation by aggressive alien species; Threat 4: The reduction of area of grey dunes; Threat 5: Decreasing area of meadows; Threat 6: The decrease of forest biological diversity resulting from inappropriate management; Threat 7: Decrease in area of endangered habitats due to building and due to inappropriate coastal management; Threat 8: Deterioration of endangered habitats in protected nature areas due to lack of management plans; Threat 9: The deterioration of natural habitats due to low public awareness. Information derived from a web site developed from a Life Nature Project - ‘Protection and Management of Coastal Habitats in Latvia. During the last century breakwaters at Ventspils harbour, where the River Venta flows into the sea, have interrupted the longshore sediment drift from the south and there is a broad accretion zone (300-700m in width) with foredune ridges on the southern side. Similar accretion has occurred alongside breakwaters at the port of Liepaja, forming a beach of fine sand with foredunes. To the south, the coast has fine sandy beaches 30-80 m wide with foredune ridges.

REFERENCES

Eberhards, G., 1998. Coastal dunes in Latvia. Environmental perspectives of Southeast Baltic coastal areas through time, Riga 18-25. Gudelis, V., 1967. Morphogenetic types of the Baltic Sea coasts. Baltica, 3, 123-145. Ulsts, V., 1998. Latvian coastal zone of the Baltic Sea, Riga, 96.

 http://piekraste.daba.lv/EN/ 

The web site includes a variety of pictures showing stages in dune development and some of the key species.