3.1.5 Vegetation The vegetation of Estonia is rather diverse. Forests, mires and grasslands alternate with cultivated land. Forests make up 47.2% of the territory, moreover, 1.7% is covered by bushes (Pärt et al., 2010); grasslands add up to 20% (Peterson, 1994). Peatlands with peat deposits thicker than 30 cm cover approximately 2 9,150 km . If water-logged areas with peat deposits less than 30 cm thick are included, 1,010,000 ha or 22.3% of the Estonian territory could be considered to be covered by peat (Orru et al., 1992). The zonal or climax vegetation type for Estonia’s climatic and edaphic conditions is boreo-nemoral coniferous forest dominated by Norway spruce Picea abies, together with elements of silver birch Betula pendula, aspen Populus tremula and Scots pine Pinus sylvestris. To a lesser extent also lime Tilia cordata, ash Fraxinus excelsior, mountain elm Ulmus glabra and pedunculate oak Quercus robur are found in the tree layer. Such forests grow on fertile soils and are the most productive, as to biomass, of our forest types. As a result of agricultural development, only a small proportion of broad-leaved forests have been preserved (Laasimer, 1965, 1975). Today, the majority of Estonian forests grow on soils, which are of little or no use for agriculture. Most of the forest ecosystems have been influenced by fire, logging or drainage (Lõhmus, 1995). Swamp forests are dominated by black alder Alnus glutinosa and downy birch Betula pubescens and sometimes by spruce or ash. Crepis paludosa, Thelypteris palustris, Calla palustris, Cirsium oleraceum, Filipendula ulmaria, etc. are typical species in the herb layer. Aspen, grey alder Alnus incana and most of the silver birch forests are in the secondary succession stages in Estonia, replacing other types of forests after clear-cutting or covering abandoned fields and grasslands. Most of the grasslands have developed as a result of deforestation or drainage of mires, and subsequent continuous mowing or pasturing of these areas. Paludifying grasslands (with a peat layer thickness less than 30 cm) on calcium-poor tills have evolved, as a rule, from paludifying birch forests. Wet meadows, particularly rich in plant species, are found on calcareous tills or bedrock. They are closely related to rich fens. Floodplain meadows, like floodplain fens, are spread in river valleys and lake basins. On seashore areas, mainly in western Estonia, saline flooded meadows are presented. Geobotanically, Estonia belongs to the hemiboreal (boreo-nemoral) vegetation zone (Ahti et al., 1968; Moen, 1999) as does Latvia, the northern part of Lithuania, the adjacent part of European Russia, the southernmost part of Finland, a broad belt across Sweden (south of Limes norrlandicus, e.g. Sjörs, 1967) and the southern part of Norway (Fig. 3).
The western part of Estonia together with Denmark, the Oslofjord area in Norway, a larger part of southern Sweden, the southernmost part of Finland, the western part of Latvia and Lithuania and the northernmost part of Poland belong to the slightly oceanic section (O1, Fig. 4; Moen, 1999). The eastern part is more continental. It is included in the indifferent oceanic-continental section (OC), as are the larger areas of Poland, Lithuania, Latvia and the western parts of Russia. The same section also covers the extensive parts of Finland, central and northern parts of Sweden and the eastern part of southern Norway.
ESTONIAN MIRES: INVENTORY OF HABITATS
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