Figure 37. GEZ map of Europe.
Table 22. Global Ecological Zones of Europe.
Surface area | |||
Km2 |
% of total land area Region |
% of GEZ worldtotal | |
Subtropical dry forest |
816 400 |
8.1 |
51.3 |
Subtropical steppe |
5 008 |
0.0 |
0.1 |
Subtropical desert |
0 |
0 |
0 |
Subtropical mountain systems |
149 240 |
1.5 |
3.1 |
Temperate oceanic forest |
1 287 121 |
12.8 |
71.3 |
Temperate continental forest |
2 906 694 |
29.0 |
41.9 |
Temperate steppe |
955 497 |
9.5 |
16.2 |
Temperate desert |
150 343 |
1.5 |
2.8 |
Temperate mountain systems |
605 384 |
6.0 |
8.4 |
Boreal coniferous forest |
2 195 688 |
21.9 |
25.9 |
Boreal tundra woodland |
87 788 |
0.9 |
2.2 |
Boreal mountain systems |
457 623 |
4.6 |
7.3 |
Polar |
422 632 |
4.2 |
7.8 |
Total land area |
10 039 418 |
100 |
|
The subtropical dry forest zone roughly comprises the Iberian peninsula (except the northern part), Rhone basin, Apennines peninsula, Dalmacija and Greece, as well as all European Islands of the Mediterranean Sea. The higher parts of this area, above approximately 800 m, are excluded and belong to subtropical mountain systems.
The Ecological Zone, encompassing the Mediterranean region, forms an intermediate zone between the tropical and the temperate zone. Its limitation is roughly defined by the distribution area of Olea europaea and Quercus ilex. The subtropical dry forest zone in Europe can be divided into two main latitudinal sub-zones: Mediterranean and a northern sub-Mediterranean zone. The latter forms the transition to the temperate zone.
Climate
Subtropical dry or seasonally dry forests grow in areas with a pronounced Mediterranean winter rain climate, thus with dry warm summers and cool moist winters. Severe frosts are lacking and thermo-Mediterranean areas are generally frost-free. Precipitation maxima are normally in November/December and in February/March. The summer months bring little or no precipitation. Pronounced relief structure provides luv and lee effects for substantial mesoclimatic differentiation. Average annual precipitation is between 400 and 900 mm, rarely over 1200 mm (e.g. Kerkira) or below 400 mm (south-east Spain, south-east Crete). Eastwards the amount of precipitation is slightly decreasing. Average temperatures of the warmest month are between 25° and 28°C, those of the coldest month between 6° and 13°C. Toward the north, in the sub-Mediterranean zone, summer drought is still characteristic but less distinct. Additionally, frosts are more common here and winter temperature is lower. Evergreen sclerophyllous tree species become replaced by relatively drought resistant deciduous tree species.
Physiography
Most of the Ecological Zone is folded in the Alpidic period, while large areas of the Iberian peninsula have their origins in the Variscian period. The geology is diverse, but the prevailing bedrock is Mesozoic or Tertiary, locally volcanic. The relief of this zone is quite varied and is expressed in a small-scale segregated landscape. Erosion processes are common and occur especially at the beginning of the rainy season after the summer drought. The erosion is enhanced by shallow or marly soils with the consequence of rapidly draining water. Due to the high sediment load, several rivers discharge into extensive deltas. Fossil Terra rossa (chromic luvisols) dominates on lime while Mediterranean cambisols have developed on siliceous bedrock. Degraded soils result mainly from anthropogenic impact and they are widespread.
According to altitude, the Mediterranean zone is generally subdivided into four belts: thermo-Mediterranean, meso-Mediterranean, supra-Mediterranean and oro-Mediterranean. Thermo- and meso-Mediterranean correspond to the conventional definition of Mediterranean. The thermo-Mediterranean belt comprises the warmest regions in the southern coastal strip with species like Ceratonia siliqua, Olea europaea subsp. oleaster, Pistacia spp. Colline altitudes, up to 800 m, in Mediterranean mountains are characterized as supra-Mediterranean.
Vegetation
The original zonal vegetation was evergreen sclerophyllous forest. Since some of the world’s most ancient civilisations originated in the Mediterranean region, the natural vegetation has been impacted considerably and over large areas has given way to cultivation. The tree species composition of Mediterranean sclerophyllous forests is usually rather monotonous. Only one species dominates the canopy, often one of the evergreen oak species. Quercus ilex competed most successfully at humid-subhumid sites; it is represented on the Iberian peninsula outside of Cantabrica and Catalonia by Q. ilex subsp. rotundifolia, in the rest of the Mediterranean area by Q. ilex subsp. ilex. The tree layer is 15 to 18 m tall with a closed canopy; the shrub layer is usually 3-5 m tall with species such as Buxus sempervirens, Viburnum tinus, Phillyrea media, P. angustifolia, Pistacia lentiscus, P. terebinthus, Rhamnus alaternus, Rosa sempervirens, etc. Lianas are present and the herb layer is sparse. In drier and winter-colder areas Q. ilex is replaced by Q. coccifera. Quercus coccifera is particularly forest forming in the east, while in the west it hardly becomes higher than 2 m. In meso-Mediterranean areas, particularly in the transition belt to sub-Mediterranean zone, deciduous tree species can be more strongly involved. Anthropogenic oak forests and maquis with small proportion of oak species have often a close evergreen bush layer, which is usually formed by Erica arborea, Arbutus unedo or A. andrachne. At particular humid sites Laurus nobilis and Myrtus communis are frequent. Especially in the west Quercus suber forms distinct forest types.
In thermo-Mediterranean areas oaks are limited to special sites or climatically moderated mountain areas; here Pinus halepensis is often the prevailing tree species on light soils in coastal regions and on calcareous rock (in the Aegean and in the east-Mediterranean P. brutia). By their resistant bark and the high regeneration potential by seed germinating, Pinus halepensis and P. brutia tolerate fire better than other tree species and profit in such a way from forest fires.
The most common type of shrub species of the thermo-Mediterranean is Pistacia lentiscus, usually a shrub less than 2 m high, rarely as a tree of up to 6 m. It often grows together with the wild form of the olive tree (Olea europaea subsp. oleaster) and Ceratonia siliqua. Further important stand forming and widespread woody species are Juniperus phoenicea and J. oxycedrus subsp. macrocarpa. The herb layer is species poor. Particularly shadow-tolerantly and widespread fern-like species occur (Asplenium onopteris, Selaginella denticulata), evergreen, partly climbing half-shrubs and lianas (Ruscus aculeatus, Asparagus acutifolius, A. aphyllus, Smilax aspera, Rubia peregrina, R. tenuifolia) as well as geophytes (Cylamen species, Arisarum vulgare and other Araceae). Furthermore, grasses, such as Piptatherum miliaceum, P. coerulescens and Ampelodesmos mauritanica, grow in the protection of low sclerophyllous shrubs.
Particularly in the Apennines and in sub-Mediterranean regions, at cooler and better water-supplied sites, mixed deciduous oak forests replace sclerophyllous forest; in the west-Mediterranean represented by Quercus pyrenaica, Q. faginea, eastward by Quercus pubescens and in the middle and east-Mediterranean by Quercus cerris forests. Most of these forests are mixed ones with various tree admixtures.
This Ecological Zone comprises the Iberian mountains (Cordillera Cantabrica, Sistema Central, Sistema Berico, Penibética, Pyrenees), the Apennines, the Greek mountains (Pindus, Olympus, Peleponnesus, Crete), as well as the mountains of Corsica and Sardinia.
Climate
The mountain region of the (sub-)Mediterranean zone is characterised by higher precipitation and a shorter summer drought period than the adjacent lowland region. Due to higher altitudes the annual temperature totals are less, too. Accordingly the frequency of frosts increases.
Physiography
The mountain zone starts at about 800 m, partly from 600 m upward and exceeds up to 2000, locally to 3500 m. It is classified as oro-Mediterranean belt (montane to subalpine) within the Mediterranean region. Due to large relief energy and extensive erosion shallow soils are common. They vary corresponding to the bedrock from rendzina to leptosols. In addition, calcisols (calcic cambisols) and other cambisols occur. The dominant bedrock is Mesozoic or Tertiary, locally volcanic. Folded in the Alpidic period, volcanism is a recent feature in this region.
Vegetation
In contrast to the Mediterranean sclerophyllous forests the vegetation of the subtropical mountain belt is indicated by mainly deciduous oak species (Quercus pyrenaica, Q. faginea, Q. petraea, Q. frainetto, Q. pubescens). These forests are usually quite close and shady. On the Iberian peninsula Quercus pyrenaica forests dominate on siliceous bedrock, while Q. faginea occupies base-rich sites. In the Pyrenees and eastward Quercus pubescens becomes more important in addition to the other oak species. In the subcanopy tree species like Fraxinus ornus, Ostrya carpinifolia and Carpinus orientalis are widespread. Within the sequence of altitudinal belts the deciduous oak forests are replaced higher up by closed and shady Fagus sylvatica forests, partly with Abies alba, Picea abies, locally with Betula pubescens. In the Apennines, beech forests with Abies alba in the tree layer and Geranium nodosum in the herb layer characterize the vegetation of this belt. Southward, Geranium versicolor becomes an important species. Additionally Quercus cerris forests, partly with Q. frainetto, are constituent of this region. In the Greek Pindus mountains Abies borisii-regis replaces Abies alba and dominates the mixed beech-fir forests. At higher altitudes the oak and beech forests are replaced by juniper and cypress woodland (Juniperus thurifera, J. excelsa, J. foetidissima, J. polycarpos, Cupressus sempervirens) or by pine (Pinus nigra agg.), as well as fir forests (Abies pinsapo on the Iberian peninsula, A. cephalonica in Greece). Oroxerophytic vegetation of thorn-cushion types with various Astragalus species grows in the highest areas of the mountains above the woodline.
The temperate oceanic forest zone combines spatially separated areas and comprises the Portugal-Spain coastline (Galicia, Asturia, Cantabrica, Euskal), the British Isles except the Scottish Highlands and the mountainous regions, France apart from the south-east mountainous and Mediterranean parts, Central Europe west of a rough line Danzig-Erfurt-Vienna and south of the Alps including the Po plain. In Scandinavia all of Denmark, southernmost Sweden and a narrow strip along the coast of Norway are included. Additionally some climatically sheltered fjords up to the 64° north belong to the temperate oceanic region.
Climate
The climate of the Ecological Zone is influenced by the Gulf Stream and moderated by the proximity to the ocean. The influence decreases however land inward and is replaced in the Po plain by a different climatic parameter with similar effects. The average annual temperature ranges from 7° to 13°C and annual rainfall varies from 600 to 1700 mm. While in coastal areas the temperature of the coldest month does not fall below 0°C, in the inland mean temperature is locally below 0°C.
Physiography
Mesozoic geological formations dominate this region. To the west, Precambrian and Palaeozoic bedrock predominate, while in the east Tertiary and Quaternary material are widespread. Cambisols are the most extensive soils in the Ecological Zone. Podzoluvisols and podzols occur in the northern and eastern parts and locally leptosols have developed on acidic or alkaline rocks. At the coastline of the Northsea fluvisols cover large areas; further inland they locally occur along bigger rivers and streams.
Vegetation
The vegetation is dominated by various types of beech forests and mixed beech forests (Fagus sylvatica). They are most extensive in Germany and neighbouring countries. Pure beech forests are relatively dense. In oceanic parts Ilex aquifolium is a characteristic species of the shrub layer. The herb layer may vary from poor to rich in species. Beech forests can be classified by nutrient and water supply. On nutrient poor, acidic soils beech is partly mixed with Quercus robur and Quercus petraea in the canopy. These stands are poor in species. Typical representatives of the herb layer are Deschampsia flexuosa, Pteridium aquilinum and Vaccinium myrtillus. On high-nutrient or base rich sites the number of plant species increases considerably and in spring many of these beech forests are covered by a luxurious geophytes carpet. Today, natural beech forests have been extensively converted into farmland. If they remained as forests they are often transformed into mixed oak-hornbeam forests. Large areas have been reforested with spruce- and Douglas fir.
On very poor, mostly sandy and acidic soils, species-poor oak forests (Quercus robur, Q. petraea) are dominating the landscape. They are accompanied by birch (Betula pubescens) on wetter sites. After clearing and pastoral use, dwarf shrub heath and acidic dry grassland develop. Agricultural use involves potato and grain cultivation.
Outside the distribution area of beech, oak-ash forests (Quercus robur, Fraxinus excelsior) with Corylus avellana and a relatively rich herb layer occupy base-rich, often calcareous soils. Oak-hornbeam forests (Carpinus betulus, Quercus petraea) dominate periodically moist soils. They often have a distinct vertical structure with a canopy and subcanopy. South of the Alps Quercus cerris, a thermophilous component may occur together with oak and hornbeam. In the southwest of the zone Quercus pubescens forests occupy areas under the influence of the milder climate.
Azonal vegetation types include flood plain and alluvial forests with Quercus robur, Ulmus laevis, U. minor, Fraxinus excelsior, in combination with willow and poplar alluvial forests (Salix alba, S. fragilis, Populus nigra, P. alba). Mires and, concentrated in oceanic parts, blanket bogs may occur as well as swamp and fen forests (Alnus glutinosa, Betula pubescens). They are locally of significant importance. Large-scale oak-ash forest and elm-ash forests (Quercus robur, Fraxinus excelsior, Ulmus glabra), occurring in the marshlands, are characteristic for the Ecological Zone. Early cultivation made these forests disappear and large areas of the original deciduous forests have been cleared. Therefore, the current area of forest and woodland for example in Denmark aggregates to around 12 % of the total land area. In addition, many deciduous stands have been replaced by coniferous forests.
The continental temperate zone is adjacent to the oceanic region within the temperate domain. Roughly it has a triangular shape with the corners in Oslo, Sofia and Ufa. South Sweden, Eastern Europe south of the line Helsinki, Novgorod, Perm and north of the line Bucuresti, Charkov, Ufa belong to the continental temperate region. Additionally, most of the Balkan Peninsula is part of this Ecological Zone, as well as the foothills of the Crimean and Caucasus mountains.
Climate
Due to the smaller influence of the Gulf Stream, annual rainfall in the continental temperate forest zone gradually decreases from the west (c. 700 mm) to the east (c. 400 mm). Much of this region is marked by warm summers and cold winters. Mean annual temperature is about 6°-13°C in the west and decreases to 3°-9°C in the east. Accordingly the temperature of the coldest month ranges from below 0°C in Scandinavia and around 0°C at the Balkan to below - 10°C in the Ural mountains. In the northern parts of the continental Ecological Zone more than two months of the year have a mean temperature below 0°C. Additionally precipitation diminishes from northwest (> 700 mm) to southeast (400 mm). Locally in the foothills of the Caucasus rainfall is very high.
Physiography
The northern parts of the Ecological Zone are largely impacted by the glacial period and were covered by the ice sheet during the maximum extent of the ice. In this region podzols are the most important soil type. Locally, on more nutrient-rich bedrock, luvisols and rendzinas occur. In the western parts and in the south cambisols, leached brown forests soils and chernozems have been established under periglacial conditions.
Vegetation
The prevalent vegetation of the temperate continental Ecological Zone comprises various forest types, distributed along local and regional gradients in climate and nutrient availability. In the northern parts mixed coniferous-broadleaved forests form a belt parallel to the circle of latitude. Spruce forests (Picea abies) cover most of the area. To the east Picea obovata may occur. In these hemiboreal coniferous forests broad-leaved trees like Quercus robur, Tilia cordata, Ulmus glabra, Acer platanoides play an important role in the canopy. The shrub layer is rather poorly developed while herb layer may be rich. On highly acidic, sandy, dry to moderately moist/ partly periodically wet soils pine forests replace spruce. Natural forest stands are dominated by Pinus sylvestris, partly with Picea abies in the northeast, intermixed with Quercus robur, Tilia cordata in the southeast. The canopy of conifers is open to dense. A sparse shrub layer with Juniperus communis, Sorbus aucuparia, Frangula alnus may occur while the herb layer can be poor or rich. Typical ground vegetation are dwarf shrubs (Vaccinium myrtillus, V. vitis-idaea, Calluna vulgaris) and grasses (Deschampsia flexuosa, Koeleria glauca (in the east)). Additional types with abundant moss and/or lichen carpets occur. Soils do not produce good agricultural yields and land is therefore mainly used for forestry (pine) and in some cases as extensive pasture (sheep, goats) or farmland (rye, barley, potatoes).
Further south, deciduous broad-leaved forests are represented by mixed oak-hornbeam and mixed lime-oak forests. Mixed oak-hornbeam forests are predominant on fresh to moist, often hydromorphic soils. The trees forming these stands include Quercus robur, Quercus petraea, Carpinus betulus and Tilia cordata. Associating species like Fraxinus excelsior and Acer campestre are also important. The shrub layer alternates between luxuriant and poorly developed, while the herb layer is generally rich in species. Mixed lime-oak forests are found east of the distribution boundary of mixed oak-hornbeam forests continuing the belt of broad-leaved forests eastwards. The tree layer is dominated by Quercus robur and Tilia cordata. Depending on nutrient level, the shrub and herb layer are often sparse. Land clearing has massively decimated this type of forest.
Most of the subcontinental-sub-Mediterranean thermophilous mixed sessile oak, bitter oak and Balkan oak forests are distributed in the sub-Mediterranean and pannonic area. They occur mainly in the southeast of Europe and the Balkans (Romania, Bulgaria, Yugoslavia). Species-rich, more open, mixed forests dominated by Quercus cerris and Quercus frainetto occupy the central part of the Balkan peninsula. They consist of a well-developed shrub layer and many thermophilous species in the herb layer. Today, dense canopy forests are strongly reduced and isolated after long exploitation for coppice with standards system, meadow and pasture cultivation, agricultural use as well as woodland pasture.
The subcontinental forest steppe zone extends from southwest to northeast and forms a broad belt of deciduous forests intermixed with hemiboreal coniferous woods and true steppes on chernozem. Ratio between woodland and open land depends on relief and exposure; treeless patches on south-exposures were probably extended by human impact. Quercus robur dominates the tree layer, interspersed with Acer tataricum, Acer campestre, Carpinus betulus (only in the West) and Tilia cordata. The herb layer is very rich in species with meadow steppes including species of Stipa, Festuca, Bromus, Carex, Agrostis, Trifolium, Salvia and Centaurea. Original forests have been cleared to a large extent and transformed mostly into intensive farmland (wheat cultivation), rarely still into traditional meadow- and pasture cultivation.
Swamp and fen woods occur in small patches across the entire Ecological Zone. Extensive areas of this vegetation still exist in the lowlands of Poland (Biebrza-Narew lowland, Sandomierer lowland) and Belarus (pripet lowland). On permanently wet peat or peaty gley soils with permanent high groundwater level the dominant tree species is Alnus glutinosa, in the Northeast with Picea abies. The shrub layer is weakly developed. The ground layer consists of sedges, grasses and tall herbs.
Flood-plain vegetation is prominent along the middle section and lower course of the large rivers Rhine, Elbe, Oder, Vistula, Pripet, Desna, Volga, Save and Danube, on mostly rich, loamy to clayey and regularly flooded alluvial soils. Due to long-term inundation willow and poplar alluvial forests (Populus nigra, Populus alba, Salix alba, Salix fragilis) are rather poor in species. Hardwood flood-plain vegetation is highly varied in structure with Quercus robur, Fraxinus excelsior, Ulmus minor, Ulmus laevis and Fraxinus angustifolia (in south east Europe). Shrub layer consists of Corylus avellana, Sambucus nigra, Crataegus laevigata, Euonymus europaea and Cornus sanguinea. In spring, appearance of geophytic vegetation in the herb layer (Anemone nemorosa, Ranunculus ficaria, Gagea lutea, Corydalis cava) is a characteristic feature, while in summer nitrophilous herbs (Aegopodium podagraria, Urtica dioica, Anthriscus sylvestris) appear. River regulation and embankment have resulted in a strong decline of (near-)natural habitat and nowadays only fragments of original flood-plain forests remain.
This Ecological Zone occupies the area south of the line between Bucuresti and Ufa excluding the Caspian plain. To the south the zone is delineated by a line from the Crimean peninsula to the mouth of the Terek River.
Climate
The climate varies with geographic location. Towards the east, the aridity is increasing as a result of decreasing precipitation, higher maximum temperatures and a stronger continentality. In the western parts, long cold frosty winters occur with temperature declining to -30°C and less. Winters are even colder and more severe in the east. In the Pontic lowlands and in the Azov plain the moderating influence of the Black Sea and the Azov Sea is notable. The mean July temperature reaches 20°-22°C in the west, in the east 25°C. Due to the low annual precipitation (in the west from 300 mm to 450-500 mm, in the east from 250 mm to 350-400 mm) and the high summer temperatures there are often dry, wind-rich periods. This phenomenon causes partial draining of the herb layer and forces the plants into a resting stage. A water deficit situation is characteristic for this Ecological Zone.
Physiography
Relief of the steppe zone is quite diverse, with various exposures and uplands forming the landscape of this semiarid region. Bedrock is characterised by types of alluvial and aeolic deposits. Since evaporation exceeds precipitation, no soil leaching but accumulation of easily soluble salts occur. Due to this feature large areas in the south of the steppe are build up of chernozems. Additionally solonetz-kastanozems occur, which often form complexes with solonetz soils. At the boundary to the deserts solonchaks occur.
Vegetation
Steppes, the main vegetation of the semi-arid region, are characterised by perennial xerophilous and often xeromorphic grasses (Stipa, Festuca, Koeleria, Cleistogenes, Agropyron, Poa and Helictotrichon spp.) and herbs (e.g. Galatella, Tanacetum spp.). The portion of herbs decreases towards the southeast. Additional components of the vegetation in the steppe zone are ephemeroids and geophytes as well as shrubs (e.g. Spiraea, Rosa, Chamaecytisus, Prunus, Amygdalus, Caragana spp.). Tomillares, Thymus steppes and petrophytic predominantly dwarf semishrub and dwarf shrub communities on rocky habitats are frequent. The presence of hemihalophyts and halophyts is typical for the steppe zone, particularly the southern part. Accompanying forests (mainly Quercus robur) are confined to sites with sufficient water supply: at slopes and in hollows, depressions and on tidal terraces.
The temperate desert zone corresponds geographically with the Caspian plain. Additionally the Transcaucasian lowland, the Kura plain, the area of Baku and the borderland of Armenia to Iran belong to this Ecological Zone.
Climate
The climate of the deserts in the temperate zone is characterised by a pronounced aridity and continentality: very low amounts of precipitation (50-250 mm); high evaporation, which exceeds the yearly precipitation to tenfold; distinct dryness during the vegetation period; high summer temperatures (July mean temperature 24°-27°C); and a cold winter (January mean temperature around -10°C) with thin snow cover.
Physiography
The harsh desert climate lead to the development of a typical desert relief with pronounced erosion and aeolic processes. In the Turanic deserts two soil types dominate: brown desert soils in the north and grey-brown desert soils in the central and south region. In the Caspian lowland light soils dominate (loamy sands and sands). Large surfaces in the desert area are formed by solonetz, solonchak and takyrs (= bare, even pan like clay soils).
Vegetation
Desert vegetation clearly reflects the physical soil characteristics. Dwarf semishrub deserts on clayey soils are poor in species. Only one perennial species dominates accompanied by 1-3 other species. Annuals are always present (e.g., Allium, Eremurus, Ferula, Rheum, Tulipa, Carex, Poa species) and their abundance depends on the actual weather conditions.
Hemipsammophytic vegetation on loamy-sandy soils is richer in species. They differ by specific grasses (on non- and weakly salty soils) or by dwarf semishrub communities (on soils with higher salinity). Sandy soils are characterized by psammophytic vegetation (with dwarf semishrub, semishrub, shrub, Stipa spp., Agropyron fragile, Carex physodes and specific herbs of sandy soils (annual or perennial). Dwarf semishrubs like Artemisia spp. are quite common as well as Anabasis-, Salsola-species. Species poor vegetation with 10-15 species is most prominent. On sandy, stony soils species number increases up to 30-40.
The temperate mountain systems include all mountainous parts of the temperate domain. More particularly the Cantabrican mountains, Pyrenees, Massif Central, Jura, Alps, the highest sites of the British Isles mountains, the Central European uplands, Carpathians, Dinaric Alps, Balkan mountains, Rhodope mountains, the High and the Low Caucasus, the foothills of the Talysh mountains as well as the southern Ural.
Climate
As highest altitudinal belt of the temperate domain the mountain region is characterised by generally higher precipitation and lower temperature. Climate of this Ecological Zone is extremely varied. According to Luv and Lee effects at particular sites precipitation varies from over 3000 mm to <500 mm (Vale d´Aosta, Erivan). The average annual temperature ranges from -4° to 8°C (locally 12°C), the average January temperature of highest altitudes fluctuates between -10° and -4°C.
Physiography
The mountains reach around 1000 m in the northern parts up to >5600 m in the Caucasus. They are mostly folded in the Alpidic period and only the northern mountains, for instance on the British Isles and the German hilly country, are formed before. Most of the region was covered by ice in the glacial period. Glacial features are obvious and widespread. Still some glaciers exist in the Alps and in the Caucasus. Due to the varied climatic and geological conditions different soil types occur, from young shallow lithosols to deeply developed cambisols.
Vegetation
Beech forests and particularly mixed beech forests with Abies alba, Picea abies, Acer pseudoplatanus, Fraxinus excelsior and Ulmus glabra characterise the vegetation of the lower belt in this region. Similar to the oceanic region pure beech forests of higher altitudes are relatively dense. Different types of beech forests can be classified related to nutrient and water supply. With higher altitudes other tree species become more prominent. To the east Fagus sylvatica (subsp. sylvatica) is replaced by Fagus sylvatica subsp. moesiaca and further eastward by F. sylvatica subsp. orientalis. An evergreen understorey may occur.
At higher altitudes fir and spruce forests (Abies alba, A. borisii-regis, A. nordmanniana, Picea abies, P. orientalis, P. omorika) replace the beech forests. Abies and Picea dominate with alternating portions. Pinus sylvestris, Fagus sylvatica, partly Quercus robur and pioneer species like Sorbus aucuparia, Populus tremula, Betula pendula play a minor role. The shrub layer, when present, consists of Sambucus racemosa, Frangula alnus, Rubus fruticosus agg. Dwarf shrubs, grasses and herbs such as Vaccinium myrtillus, Deschampsia flexuosa, Maianthemum bifolium, Oxalis acetosella, Hieracium murorum and various acidophilous mosses (Polytrichum formosum, Dicranum scoparium, Bazzania trilobata) are characteristic for the ground layer.
Around the timberline pine scrub (Pinus mugo) partly alternating with Rhododendron spp. may occur. This scrub and krummholz grades at higher altitudes into alpine grasslands, various dwarf shrub vegetation and rock and scree vegetation of the alpine to nival belt.
In western parts of the Iberian peninsula oak forests (Quercus robur, Q. pyrenaica, Q. petraea) with Betula pubescens subsp. celtiberica, ericoides and other acidophilous species cover the top of the mountains.
In the Ural the altitudinal zonation starts with lime-oak forests (Quercus robur, Tilia cordata), followed by herb-rich fir-spruce forests (Abies sibirica, Picea obovata) with broad-leaved trees like Ulmus glabra and Tilia cordata as well as pine forests (Pinus sylvestris) with Larix sibirica.
This Ecological Zone occurs in the lower parts of Iceland and North Scotland. On the continent some parts of Norway, most of Sweden, nearly all of Finland and a wide belt in the European part of Russia south of the Arctic Circle belong to this region.
Climate
Within the boreal domain the coniferous/birch forest region has a cool-temperate, moist climate, varying from oceanic in the west to subcontinental in the interior and the east. Accordingly, mean annual temperature is generally low and ranges from 8°C in Scotland to just above 1°C in the northern parts of Russia. Precipitation ranges from > 900 mm in the west to 400 mm in the east, with extremes of 1200 and 300 mm. The short vegetation period (less than 120 days with >10°C mean daily temperature) is characteristic. Evaporation is low and prolonged periods of drought are rare. Snow covers the ground for several months during the winter, more intermittently in the hemiboreal subregion.
Physiography
In the last glacial period, the north European ice sheet covered most of the boreal region. During its existence and withdrawal the ice carved out the landscape and left copious deposits which have shaped the boreal landscape in a characteristic way. The southeastern parts of this region were not covered by ice but were still greatly affected by the glacial climate and glacio-fluvial processes. The geology is characterised by old weathered sedimentary rocks and bedrock, such as gneisses and granites, generally poor in exchangeable nutrients. Locally outcrops of more nutrient-rich rocks occur. The rock formations are covered by extensive, but uneven, glacial moraine and glacio-fluvial deposits, as well as marine deposits in previously submerged coastal areas. Glacial erosion formed large undulating plains and rolling hills framed by the Scandes mountains in the west and the Ural mountains in the east, broken by occasional mountain outcrops and river valleys. Extensive forests, numerous lakes, rivers and mires form the characteristic mosaic landscapes.
Soils are generally young and shallow, with a poorly developed organic component. On well-drained ground, over large areas of the region, strongly layered, acidic podzols have formed as a result of organic acids leaching from the conifer needle litter. An intermediate soil between podzol and cambisol found in this region is podzoluvisol. Paludification, the extensive formation of peat soils or histosols, is another feature of the boreal region.
Vegetation
The glaciers of northern Europe essentially wiped the land clean of most plants and animals. This great natural perturbation is still reflected in the species and vegetation diversity of the boreal region. Most of the boreal forests are dominated by a few conifer tree species, primarily spruce (Picea abies) on moister ground and pine (Pinus sylvestris) on drier ground. East of the White Sea, mainly closer to the Ural Mountains, Siberian conifer species like Pinus sibirica, Abies sibirica and Larix sibirica may also occur. Deciduous species like birch (Betula spp.), aspen (Populus tremula), alder (Alnus spp.) and willow (Salix spp.) are characteristic as early successional stages (especially birch and aspen) or may form smaller stands among the conifers. Stands of deciduous trees are mainly associated with special habitats, often disturbed by fire or floods, or occupy particular soils. In Iceland only birch scrub and open forests occur due to the specific climate and phytogeography of the island. The vertical structure of mature boreal forests is generally quite simple, with a well-defined tree layer and a rather poorly developed shrub layer. For much of the boreal forests, the nutrient availability for the vegetation tends to be rather limited. The ground layer is dominated by ericaceous dwarf shrubs (e.g., Calluna, Vaccinium, Empetrum spp.), varying from dry and poor lichen and Calluna-dominated pine forests to somewhat moister and richer Vaccinium-dominated spruce forests. Grasses and herbs are more common in the ground layer on soils richer in nutrients, tall herbs being especially characteristic for the rather uncommon richest forests. The ground layer is often well developed, being dominated by bryophytes under moist conditions and lichens (e.g., Cladonia, Cetraria spp.) on drier ground with more accessible light. In moist old forests, an epiphytic vegetation of lichens and bryophytes is often well developed.
Mires, ombrotrophic and minerotrophic types, constitute another dominating feature of the landscape of the boreal domain. In parts of northern Finland, mires cover almost 50% of the land area. In other parts of the region, the extent of mires may vary, but generally they form characteristic landscape elements in mosaics with various forest types. Characteristic raised bogs, with a central raised area of peat, are mainly found in the southern part of the boreal domain. They are dominated by various Sphagnum mosses, but only a few vascular plants may be found on bogs, such as species of the genera Carex, Juncus, Eriophorum, additionally Calluna vulgaris and stunted pines (Pinus sylvestris). Special types of palsa mires, which are heaps of peat with a nucleus of ice, may be found in areas of permafrost, generally surrounded by minerogenous mires. The most common types of mire in the boreal region are fens on level or gently sloping ground, often mixed with smaller areas of open water, raised bogs and drier, firm ground. In Fennoscandia in particular, large areas of mires have been ditched and partly drained over the last 100 years for purposes of agriculture or forestry. This is especially the case for richer fens. The intensity of forestry in the Boreal region has increased considerably over the last 100 years. With modern technology, today forestry has the potential to restructure and transform boreal forests and the landscape over wide areas at an unprecedented scale. Since so much of biodiversity in the Boreal region is associated with forests, forestry may be considered the major force affecting biodiversity over much of this Ecological Zone.
Current forestry practices in the Boreal region are still somewhat varied, depending on access to technology, economic constraints, ownership structures and the structure and productivity of the land itself. Nevertheless, the basic model of clearcutting and forest stand management, often with planting of non-native trees, is now widely applied.
Boreal tundra woodland forms a narrow belt on the Kola peninsula and along the Arctic Circle to the Ural mountains.
Climate
Tundra woodlands are restricted to cold and humid climate. The average annual precipitation varies between 700 mm on the Kola peninsula and 500-550 mm east of the Pecora River. The mean annual temperature on the Kola peninsula amounts -1° to -2°C, in the north of the Russian plain -2° to -4°C (average of January -10° to -12°C or -14° to -17°C; average of July 9°-12°C or 11°-13°C). Permafrost is discontinuous but widespread.
Physiography
Altitude in this hilly country ranges from sea level up to about 500 m. Geomorphology of the region is quite heterogeneous. On the Kola peninsula old bedrock like gneisses and granites are covered by stony, shallow soils. Hilly and more or less glacial marine sites prevail in the north of the Russian plain with sandy-loamy quaternary deposits on siliceous bedrock. The geology and the actual climate support the development of podzols, podzolic gleysols and locally histosols. Cryogenous soil forming processes have induced a distinct micro relief. Soils are strongly acid (pH 4,2-4,3) to moderately acid, locally neutral.
Vegetation
The vegetation of this Ecological Zone at the forests limit comprises open woodlands of low growing trees, 4 to 6m tall, maximum up to 12m. The stands are predominantly composed of the trees Betula pubescens subsp. czerepanovii and Picea obovata. While Picea obovata dominates in the north of the Russian plain and in the Ural, Betula pubescens subsp. czerepanovii, a subatlantic-subarctic species, forms the woodland in the sub-oceanic areas of northeast Europe (Kola peninsula, sites at the left bank of the Pecora River). In the eastern parts of the zone Larix sibirica open woodlands may occur as small isolated stands on sandy soils. The shrub layer consists of Betula nana, Ledum palustre. In the herb layer various dwarf shrubs (Vaccinium-species, Empetrum hermaphroditum, Arctostaphylos spp.) form patches between the herb species (Carex globularis, Rubus chamaemorus, Deschampsia flexuosa, Equisetum sylvaticum, Trientalis europaea). Mosses and lichens (Pleurozium schreberi, Polytrichum commune, Cladonia spp., Cladina spp.) constitute in varying densities the ground layer. In the eastern parts Siberian species such as Larix sibirica, Abies sibirica, Calamagrostis holmii are present.
Due to the hilly landscape the tundra woodlands are often linked together with arctic-subarctic ombro-minerotrophic mires, especially palsa mires. These mires occupy the wet depressions, while the tundra woodlands cover the slopes and other well-drained sites.
The boreal mountain zone consists of 4 isolated mountainous regions. From the west to east they are the uplands of Iceland, the Scottish Highlands, the Scandinavian mountains and the parts of the northern Ural belonging to the boreal domain.
Climate
The average annual temperature is nearly everywhere below 4°C. Only in coastal areas of south Norway the temperature reaches 7°C. Annual precipitation amounts 400 mm in the east and increases westwards. Precipitation is particularly high at the Luv side of the mountains.
Physiography
Iceland has a volcanic origin, while the Scandinavian mountains and the Scottish Highlands are formed in the Precambrian and Cambrian period. Like the boreal lowlands, the mountains are highly affected by the ice age. Various glacial features like hummocks, trimline and fjords mark the landscape. Owing to various geomorphological and geological conditions different soil types occur, including podzoluvisols, podzols, gelic-dystric cambisols and gelic-dystic gleysols. The combined effects of glaciation and the cool, moist climate have strongly influenced soil formation and structure.
Vegetation
The western boreal birch woodlands have the widest distribution area in this Ecological Zone. They are composed of more or less open Betula pubescens subsp. czerepanovii forests partly with pine forests (Pinus sylvestris) in the eastern parts. The vertical structure is simple, with dwarf shrubs, mosses and lichens as common components. At higher altitudes above the timberline the forest vegetation is replaced by boreal alpine as well as subnival and nival vegetation. Dwarf shrubs such as Salix herbacea, Betula nana, Empetrum nigrum, Vaccinium myrtillus, Kobresia myosuroides and herbs and grasses dominate the vegetation of dwarf shrub communities, grass heaths, scree vegetation and windswept heaths.
In Iceland sparse mountain pioneer vegetation occupies the highest altitudes while in the Scottish Highlands blanket bogs, heaths and dwarf shrub vegetation covers the rounded hills. In the Ural mountains coniferous forests (Picea obovata, Pinus sibirica, Abies sibirica) are common and widespread.
The Polar domain is restricted to the Island Jan Mayen, archipelagos of the Barents Sea, the north coast of the Kola peninsula east of the North Cape, as well as the European part of Russia north of the arctic circle including the neighbouring isles. In the Ural mountains the polar region stretches far to the south (nearly to 64° north).
Climate
The polar domain is characterised by a distinct cold climate. As southern boundary of the tundra for instance the 10°C July isotherm is defined. Temperature and precipitation vary, depending on geographical location and the proximity to the sea. Coastal regions under the influence of the gulf stream have a more balanced climate and a higher precipitation (Vardø: 1.1°C, 600 mm; Kolgujev: -3°C, 224 mm). The number of days with mean daily temperature above 0°C amounts to 55-118.
Physiography
Long frost periods, accompanied with cryoturbation, solifluction and permafrost, determine the landscape. Lithosols and tundra soils with polygon pattern are the main soil types.
Vegetation
In these extreme conditions trees are absent. They are replaced by shrub and dwarf shrub tundra (Betula nana, Salix spp., Empetrum spp., etc.). Further northwards the tundra gradually gives way to the arctic polar deserts with widely scattered individual vascular plants, where the July isotherm is 2°C and the roots of the plants do not form a continuous system.
REFERENCES
Bohn, U., Neuhäusl, R. et al. 2000/2001. Map of the natural vegetation of Europe. Maps (9 sheets scale 1:2.5 million, legendsheet, general map scale 1:10 million), Legend (153 pp.), Text (explanatory textbook, CD-ROM). Bonn-Bad Godesberg. Ed: Bundesamt für Naturschutz.
ETC/NC. 2001 (manuscript). Report on Europe´s Biodiversity. Paris.
Walter, H. & Breckle, S.W. 1991. Ökologie der Erde, Bd. 4: Spezielle Ökologie der Gemäßigten und Arktischen Zonen außerhalb Euro-Nordasiens. 2nd ed. G. Fischer. Stuttgart. 586 pp.
Walter, H. & Breckle, S.W. 1994. Ökologie der Erde, Bd. 3: Spezielle Ökologie der Gemäßigten und Arktischen Zonen Euro-Nordasiens. 2nd ed. Stuttgart. G. Fischer. 726 pp.
Walter, H. & Lieth, H. 1960-67. Klimadiagramm-Weltatlas. VEB-G. Fischer. Jena.
