Alpine flora describes all plant species that occur in the Alps above the tree line . Since this limit fluctuates regionally, species are also included that have their main distribution area in the mountains but which already thrive in the valley.
The composition of the flora varies greatly depending on the geographical location and natural history of immigration; some species occur only sporadically. The composition also depends on the altitude, which is divided into various ecological altitude levels , often with smooth transitions. In addition, soil structure and soil composition play an important role: on lime and dolomite there is a different species complex than on silicate ; where lime and silicate meet, there is usually a great diversity of species.
Alpine plants that are brought into lower elevations by streams and rivers are known as Alpine floods .
Origin of the alpine flora
After the retreat of the ancient sea of Tethys about 60 million years ago, a humid and subtropical climate prevailed in Central Europe, with an annual mean temperature of 22 ° C. This caused a species-rich, predominantly evergreen vegetation with palms, magnolias, sequoias, epiphytic bromeliads and bald cypresses. The subsequent deterioration in the climate and the unfolding of the Alps in the early tertiary period led to the displacement of these tropical plants. However, small relatives of the vegetation of that time can still be found in the Alpine region, such as the snow heather , the houseleek and the lady's mantle . The newly formed high mountain range was populated in the following period on probably three ways by plant species not previously found here:
- Immigration and adaptation of lowland plants from the plains north of the Alps (e.g. hawkweed )
- Immigration from other areas with an alpine climate, especially from Central Asia ( Altai , Himalaya ): These include saxifrage species , columbines , Mannsschild species , alpine roses , some gentian species , alpine poppies .
- Immigration and adaptation of plants from the Mediterranean area : crocuses , daffodils , orchids , bluebells and others.
The following epoch of the Ice Ages brought further decisive changes : plants were displaced on the one hand from the alpine heights to lower elevations, on the other hand from the Arctic-Scandinavian region to the warmer south. The lowland flora largely died out. The alpine flora was pushed into the foreland by the advancing ice. In extreme cases, the ice-free zone between the Alpine and Scandinavian glaciers was only a few hundred kilometers, which resulted in an intensive mixing of the flora. The spread of z. B. White silver arum ( Dryas octopetala ), herb willow ( Salix herbacea ) and chamois heather ( Loiseleuria procumbens ) are therefore referred to as arctic-alpine. The displacement from the main Alpine ridge to the north and south also had the effect that remaining stocks of subtropical plants (especially subtropical tree species) died out due to natural barriers (Mediterranean in the south, Scandinavian glaciers in the north).
On ice-free islands, so-called nunataks , within the alpine area (e.g. in the Ticino Alps , the Bergamasque Alps or the Julian Alps ), some plant species had the opportunity to survive the cold spell. These refuges are therefore still particularly rich in ancient plant species whose origins can be traced back to the Tertiary. Tertiary relics are e.g. B. the cobweb saxifrage ( Saxifraga arachnoidea ) in the Lake Garda area and the Carinthian Wulfenia ( Wulfenia carinthiaca ) on the Gartnerkofel.
In the post-glacial period, the vegetation migrated back to the previously glaciated areas. The large forests in the Alps date from that time, with the tree line at times 300 to 400 meters higher than it is today.
Adaptation to alpine living conditions
Alpine plants are forced to adapt to the special living conditions of the mountain heights. To this end, they have developed various behaviors that distinguish them from related or even from the same species in extra-alpine regions.
Effect of snow in the high mountains
The vegetation pattern in the forest-free area is shaped by the local relief. The duration, thickness and density of the snow cover are decisive factors for plant growth. By snowdrifts z. B. blown away snow from the hilltops, but collected in the hollows, which is why different societies settle in hollows and on knolls.
It is positive that a snow cover acts as an insulation layer, with new snow insulating better than compressed old snow due to the higher proportion of air. It also offers protection against dehydration, which is a particular threat to plants with evergreen leaves because they need water for photosynthesis, which the frozen soil denies them. The snow cover also protects the green leaves from the strong radiation in the mountains by reflecting the light back on the snow crystals. Protection against winter storms with ice crystals, which could damage the plants, is also beneficial for the plants.
The negative effect is that winter and snowfall shorten the vegetation period of the plants: the plants are forced to bloom and reproduce in a limited time and to build up winter reserves. In addition, the relatively high ground temperature (around 0 ° C) caused by snow keeps plants active and they breathe stored sugar reserves. Another negative factor is the snow pressure on the plants and the risk that the plants will be torn out of their anchoring by sliding snow.
This environmental situation has led to different behaviors. Some plant species shed their leaves, but they are then forced to form new ones in spring. Others keep their leaves and only add a few new ones in spring, which speeds up photosynthesis. Some plant species will germinate from scratch once the snow melts.
- Example alpine roses
The alpine roses ( Rhododendron hirsutum and Rhododendron ferrugineum ) have adapted to these conditions in that they already perform their full photosynthesis at a third of the maximum light irradiation and achieve 80% of the substance gain between 5 and 25 ° C. Their loose growth form offers little resistance to the wind and thus keeps the temperature in the optimal range. However, there is a risk of dehydration. In contrast to other plants that form dense cushions, such as chamois heather ( Loiseleuria procumbens ), the water supply from the soil via the roots must be guaranteed.
Snow protection helps the plant against freezing. In silicate areas, for example, the rust-leaved alpine rose ( Rhododendron ferrugineum ), which is typical of Swiss stone pine forests, dominates in places where the snow cover for Swiss stone pine ( Pinus cembra ) lasts too long (and also in areas where Swiss stone pine was cleared in ancient times to gain pastureland). Accordingly, the lime-loving lashed alpine rose ( Rhododendron hirsutum ) occurs in limestone regions either in combination with mountain pine ( Pinus mugo ssp. Mugo ) or in long, snow-covered areas. It can also be found on rubble heaps, where it plays a key role in stabilization and soil formation.
Climate and microclimate
The climatic conditions are decisive for which plant species predominate in a region. This applies in particular to the very different conditions in the Alps: In the lower elevations, the temperatures and the UV intensity are more moderate than in the high mountains; the north and west sides of the Alps receive more rainfall than the mountain ranges in the south and east; Northern slopes have less solar radiation than those facing south. These supraregional effects are often overlaid by very different microclimate zones that collide in a very small space. For example, adjacent north and south slopes often have completely different vegetation due to the different levels of solar radiation. The vegetation is also influenced by the different light and wind conditions in meadows, on the edge of the forest and in the forest itself.
In order to defy these conditions, different defense mechanisms have developed in many alpine plants:
- Upholstery or rosette growth ( stalkless catchfly )
- Dense hair ( Heavenly Herald )
- Stocky stature ( man's shield )
- Waxy coatings ( flour primrose )
These mechanisms are mainly used to protect against dehydration, which is particularly important for nival plants. The growth of the upholstery is remarkable in that it creates its own microclimate. The temperature on the surface is increased and humus and water are stored in the cushion . Compact growth generally reduces the exposure surface for wind. Another adjustment mechanism is the well-developed fine-root system of the mountain plants. It is up to five times longer than that of the valley plants. As a result, they can better absorb the rather sparse nutrients. Growth and metabolism also work better in alpine plants than in valley plants, as they can better deal with lower temperatures and strong temperature fluctuations.
In general, the Alpine region is considered to be a vegetation area with an above-average water supply. However, there are isolated locations in which only small amounts of precipitation occur. In addition, the water storage can be negatively influenced by various influences: Strong wind accelerates evaporation, debris and soil poor in humus prevent a longer storage of water supplies. This is why some species have also developed water-storing leaves, such as houseleek ( Sempervivum ) and stonecrop ( Sedum ).
As a result of the short vegetation period (at most two and a half months at 2000 meters above sea level, only a few weeks at 3000 meters above sea level), mostly only perennial plants survive in the Alps. Exceptions, however, are: dark stonecrop ( Sedum atratum ), snow gentian ( Gentiana nivalis ) and dwarf eyebright ( Euphrasia minima ). Some plant species that are annual on the plains also develop perennial forms at higher altitudes, such as the bluegrass Poa annua .
Some plants defend themselves against the risk of frost by accumulating carbohydrates . This enables them to overwinter with green leaves and to drive them out immediately after the snow has melted. Examples of this are many cushion perennials and dwarf shrubs. Others already form their flower buds in late summer and bloom immediately after the snow has melted. Typical examples are the spring crocus ( Crocus vernus ), the snow rose ( Helleborus niger ) and the spring gentian ( Gentiana verna ).
Time and energy-saving forms of behavior have also developed in the case of reproduction. Some species, for example, do without sexual reproduction and reproduce through brood sprouts, e.g. B. the nodule knotweed ( Persicaria vivipara ), or by runners.
The short growing season also has an impact on the growth of woody plants. In exposed locations, some species show only minimal annual growth; For example, the thickness of the annual rings in mountain pine or dwarf juniper is less than 0.5 millimeters.
Further examples of very slow growth: Glacier buttercup ( Ranunculucs glacialis ) is the highest plant in the Alps. However, it takes several years for the flowers to grow. The growing flower has to overwinter twice. In the first summer the flower bud is created, which fully develops in the second summer and only unfolds in the third year. This is different from the common buttercup ( Ranunculus acris ), which settles in the valley. It only takes six months for the entire plant development, from seed germination to the formation and development of the flower to seed loss.
The crooked sedge ( Carex curvula ) consists of so-called wandering nests. These shoot systems a few centimeters long are approx. 15-20 years old and their shoots are staggered one behind the other. The crooked sedge “marches” through the ground at a rate of growth of around 0.9 mm per year. New shoots grow at the top, at the end the oldest die off.
General soil conditions
Of course, the soil and its general condition also play an important role . The soil quality is determined by the mineral subsoil and the supply of organic substances. Both components are subject to extreme differences in the mountains, because the forces of erosion attack the exposed rock: the flowing water, snow and ice masses make the rock brittle. The carbonic acid in the water chemically dissolves limestone. The ice acts mechanically on the rock. In many places in the Alps there is little humus , but a lot of stone rubble ( rubble vegetation ) and rock . Depending on this, different types of vegetation can be distinguished:
- Algae are the first pioneer plants to colonize rocks and stone blocks, especially blue-green algae . They often give the rocks a green, brown, rusty red, or black hue. The algae collect the surface water that runs down the rocks and feed on the minimal amounts of washed out minerals. Even lichens will soon find enough nutrients and points of attack to coat the rock. Map lichen and ink lichen on acidic soils as well as leather lichen on calcareous (alkaline) soil are particularly widespread .
- As soon as the first traces of humus are present, these are colonized by mosses . These remove further minerals from the rock, so that humus formation is increased. By the way, they are excellent water reservoirs.
- After these preliminary developments, higher plants such as grasses and flowering plants are able to establish themselves.
Chemical nature of the soil
The chemical nature of the soil varies greatly in the Alps and is dependent on the bedrock : acidic soils (e.g. on gneiss ) and basic soils (e.g. on limestone and dolomite ) are usually very pronounced. Many plant species can only thrive on one of these types of soil. There are also mixed forms: The Clusius gentian ( Gentiana clusii ) on lime forms a so-called vicarious pair of species with the Koch's gentian ( Gentiana acaulis ) on silicate .
The reason for such preference is the supply of the plant with minerals. So is z. B. the nitrogen supply in acidic soils is much lower than in limestone soils. This becomes particularly clear when the flora in the camps of game or grazing cattle is used for comparison. Plant species thrive there that are not viable in the less well-fertilized areas, such as the white germer ( Verartrum album ) and the alpine dock ( Rumex alpinus ). These plants can still be found decades after the alpine pastures were no longer cultivated.
Plants that are dependent on pollination by insects have developed special attracting methods depending on the altitude. Bees are rarely found at heights of over 1,500 meters; here butterflies , bumblebees and hoverflies play the most important role in pollination. In order to attract their attention, alpine plant species have often developed particularly colorful, strongly scented flowers with high nectar production . The UV light, which can be perceived by many insects , also plays an important role in the coloring . In the high mountains, the percentage of wind-pollinated species also increases sharply.
The vegetation of the Alps is divided into different altitude levels , each of which is typical of certain plant species:
- Hill level (colline level) = up to ~ 500 m; it extends from the lowlands to the upper limit of viticulture and includes alpine valleys
- Lower mountain level (submontane level) = up to ~ 1,000 m; Forest step with beech , linden , oak , chestnut
- Upper mountain level (high-montane level) = up to ~ 1,500 m (Northern Alps up to 1,400 m, Central Alps up to 1,500 m, Southern Alps up to 1,800 m); Forest level with mountain forest of Book , spruce , fir , pine
- Subalpine level = up to ~ 2,000 m (Northern Alps up to 1,900 m, Central Alps up to 2,400 m, Southern Alps up to 2,000 m); Tree line, Krummholz and Alpine rose zones , larches , Swiss pines
- Alpine level = up to ~ 2,500 / 3,200 m (above the tree line); Dwarf shrub u. Grass heath zone flop , Bush book , Bush alder
- Snow level (level level) = from 2,500–3,000 m; Pioneer lawns, mosses , lichens
See also: Alpen # Flora
Alpine flora and man
Research into the alpine flora
Even Leonardo da Vinci recognized (second half of the 15th century), the alpine flora that after the occurrence of individual altitude levels can be divided, each with characteristic plant species. Francesco Calzolari , who documented an ascent of Monte Baldo around 1550, presented the first more precise records of this .
The first scientific study of the flora of the Alps goes back to the Zurich natural scientist and doctor Conrad Gessner (2nd half of the 16th century). When he climbed Mount Pilatus in 1555, he made descriptions of around 40 plants, including gentian species, some saxifrage, white germer and silver thistle. He also found in general that the plants of the mountains differ from those of the plains in terms of their appearance, with particular reference to smaller and more compact leaves . A list of plants from the mountains around Chur by Johann Schmid dates from the same period and contains edelweiss (under the name Wullblume ) for the first time .
In the Eastern Alps , and especially in the Northern Limestone Alps , is at the same time Carolus Clusius worked. In his Historia Rare Plants he describes many plants such as chamois heather, stemless gentian, silver arum and also edelweiss. His attempts to plant alpine flowers in his home garden were accompanied by numerous failures, which led him to some conclusions about the special living conditions of the plants. He creates the first Alpinum in Vienna . Even today we meet his Latinized name Clusius in the scientific names of some lime-loving plants, e.g. B. Clusius gentian , Clusius cinquefoil or Clusius primrose .
In the following 200 years, interest in the alpine flora wanes. Only the Swiss doctor and botanist Albrecht von Haller , who lived in Göttingen and published the book Historia stirpium Helvetiae on the flora of Switzerland in 1768 , set a new accent. In addition to detailed plant descriptions with many illustrations, he is the first to compare the altitude levels of the Alps with the vegetation belts of Europe from north to south. Some plants are also named in honor of Haller, such as Haller's primrose , Haller's devil's claw or Haller's pasque flower .
Late 19th century provided piece of work followed as another way the plant life of the Danube countries of Anton Kerner von Marilaun . For the first time, the dependence of vegetation on climate, microclimate and soil is examined.
The first comprehensive compilation of the alpine flora was carried out by Gustav Hegi , whose book Alpenflora was published in the first edition in 1905. With the opening up of the Alps for tourism, knowledge of the alpine flora is becoming more and more common. This is shown by the vast number of popular science books on this subject.
Botanical research has recently shifted mainly to the molecular and genetic area. This applies to both the classification of plants and the investigation of the genetic causes for adaptation to extreme living conditions.
Influence on culture and civilization
It is not surprising that the alpine flora is often reflected in everyday life in alpine countries. In Austria z. For example, typical alpine plants are depicted on the reverse of the 1, 2 and 5 cent coins. Postage stamps also show images.
Many Bavarian, Austrian and Swiss hotels are named after Edelweiss or Alpenrose; These plant names are often found in the title of Heimatfilms , and they appear in songs.
A large number of alpine plant species are part of a wide variety of herbal liqueurs. From the starchy roots of the yellow gentian ( Gentiana lutea ) z. B. Distilled gentian schnapps.
Plants and Mythology
Many alpine plants were once thought to have magical powers. Some were used as so-called professional herbs. These plants were used against "calling" (enchanting, bewitching). For this purpose, washing or smoking were carried out. Herbs were also placed in the cradle of the children or given to feed the cattle. The most striking example are the occupational herbs ( Erigeron ), which were named accordingly.
Many plant names go back to old superstitions and / or healing effects. The all man's armor ( Allium victorialis ) is supposed to make the wearer invulnerable.
Some plants are also said to have disastrous effects. The spring gentian may z. B. not be taken into the house because it attracts lightning. The opposite is said of houseleek. Planted on roofs, it is supposed to keep lightning off.
- Norbert Griebl, Alpen Pflanzen, Freya, Linz 2017, ISBN 978-3-99025-185-0 online
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- Aichele, Schwegler: Flowers of the Alps . Franckh-Kosmos Verlags-GmbH, Stuttgart 1999, ISBN 3-440-07841-8 .
- Xaver Finkenzeller: Steinbach's natural guide Alpine flowers: discover and recognize. Eugen Ulmer, Stuttgart 2010, ISBN 9783800159802 .
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- Claude Favarger, Paul-André Robert : Alpine flora - Subalpin , Kümmerly + Frey, Geographischer Verlag, Bern 1959 
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- Elias Landolt : Our alpine flora. 8th edition, SAC-Verlag, Bern 2012, ISBN 3-85902-369-1 .
- Plant pictures from the Alps after watercolors by Ferdinand Götting, Ostmarken Verlag, Vienna 1938 
- Herbert Reisigl, Richard Keller: Alpine plants in the habitat. Alpine lawn, rubble and rock vegetation. ISBN 3-437-20397-5 .
- Elfrune Wendelberger: Alpine plants. Flowers, dwarf shrubs, grasses. BLV, Munich 1993, ISBN 3-405-12868-4 .
- Manuel Werner: Which alpine flower is that? Franckh-Kosmos Verlags-GmbH, Stuttgart 2011, ISBN 9783440125762 .