Stora Alvaret
Encyclopedia
The Stora Alvaret is a limestone barren
plain on the island of Öland
, Sweden
. Because of the thin soil mantle and high pH
levels, a great assortment of vegetation is found including numerous rare species
. Stora Alvaret has been designated as a World Heritage Site
by UNESCO
due to its extraordinary biodiversity
and prehistory. The area of this formation exceeds 260 square kilometres (100.4 sq mi), making it the largest such expanse in Europe
and comprising over one fourth of the land area of the island. Stora Alvaret is not devoid of trees, contrary to a common misconception; in fact, it holds a variety of sparse stunted trees akin to a pygmy forest
. The Stora Alvaret, sometimes called the Great Alvar, is a dagger
shaped expanse almost 40 kilometres (24.9 mi) long and about 10 kilometres (6.2 mi) at the widest north end.
action from earlier ice age advances. The limestone formation itself was created about 500 million years ago in more southerly seas. Gradually hardening into limestone and drifting northward, the limestone of the Stora Alvaret contains a rich fossil record of some of the marine creatures who contributed to it. For example, orthoceratites are found in some of the present day structures on the island.
Only as recently as 11,000 years ago did the first portions of the island of Öland emerge from the Baltic Sea
, after the overpressure of the last glaciers was relieved by melting. Over the next several thousand years, more ice melted and the first wave of large mammal
s including human
s migrated across the ice bridge
from the mainland. Finally a thin soil
mantle (only two centimeters at the deepest) was formed by plant colonisation of the bare limestone
and some wind driven deposition, to create the alvar
formation of the present. In many places the limestone has no soil whatsoever upon it.
The best known early paleolithic settlement occurs at Alby
, situated on the east coast of the island, where excavations have revealed vestiges of wooden huts around a prehistoric lagoon
. Artefacts retrieved include evidence of bear
, marten
, seal
and porpoise
, but also reveal hunting and gathering technologies through discovery of bone
spear
s, elk
antler
harpoon
s and flint
.
Evidence of later ringfort
s abounds including the most well known site at Eketorp
. In the Bronze Age
and early part of the Iron Age
, extreme pressure was exerted on the limited tree species growing on the Stora Alvaret and its margins. Jannson suggests that this disappearance of trees
caused a mysterious evaporation of humans about 500 AD which is documented at Eketorp and other sites. It is thought provoking to imagine that the expanded human population
may have exceeded its carrying capacity
of this place by about 500 AD. Later, about 800 to 1000 AD various Viking
settlements appeared on the fringe of the Stora Alvaret.
The first documented scientific study of the biota
of the Stora Alvaret occurred in the year 1741 with the visit of Linnaeus. He wrote of this unusual ecosystem: "It is noteworthy how some plants are able to thrive on the driest and most barren places of the alvar". Some relict
species from the glacial age are among the flora
palette of the Stora Alvaret. A wide variety of wildflower
s and other plants are found on the limestone pavement ecosystem. Some of the species found include stonecrop, dropwort
, Artemisia
oelandica (endemic to Öland), Shrubby Cinquefoil
, Common spotted orchid
and kidney vetch. Most of these wildflowers bloom from May to July.
Numerous grasses are found on this alvar including Meadow Oat-grass
and Sheep's Fescue
; as would be expected from the occurrence of orchids, many fungi grow on the Stora Alvaret such as Hygrocybe
persistens and Lepiota
alba. Although the alvar here is known for its severely dry conditions, there are some seasonal wetlands and vernal pool
s, notably the vestigial lagoon
area northwest of the village
of Alby.
public two-lane highway
which circumnavigates the entire island. At several latitudes there are less improved roadways that run east-west and intrude directly through the Stora Alvaret. Small villages such as Stora Vickleby, Gettlinge, Grönhögen, Hulterstad, Alby, Triberga and Vället lie at the fringe of the Stora Alvaret along the perimeter highway. There are fewer and smaller villages within the alvar expanse itself: Mockelmossen, Solberga and Flisas, for example. Some of the old villages are totally deserted such as Dröstorp. At the extreme south end of the Stora Alvaret lies Ottenby
, a historic royal game farm and now a nature reserve
.
Alvar
An alvar is a biological environment based on a limestone plain with thin or no soil and, as a result, sparse vegetation. It is also known as a pavement barren although this term is also used for similar landforms based on sandstone. In the United Kingdom the exposed landform is called a limestone...
plain on the island of Öland
Öland
' is the second largest Swedish island and the smallest of the traditional provinces of Sweden. Öland has an area of 1,342 km² and is located in the Baltic Sea just off the coast of Småland. The island has 25,000 inhabitants, but during Swedish Midsummer it is visited by up to 500,000 people...
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
. Because of the thin soil mantle and high pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
levels, a great assortment of vegetation is found including numerous rare species
Rare species
A rare species is a group of organisms that are very uncommon or scarce. This designation may be applied to either a plant or animal taxon, and may be distinct from the term "endangered" or "threatened species" but not "extinct"....
. Stora Alvaret has been designated as a World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
by UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
due to its extraordinary biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
and prehistory. The area of this formation exceeds 260 square kilometres (100.4 sq mi), making it the largest such expanse in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and comprising over one fourth of the land area of the island. Stora Alvaret is not devoid of trees, contrary to a common misconception; in fact, it holds a variety of sparse stunted trees akin to a pygmy forest
Pygmy forest
A pygmy forest is a forest which, for pedological and geological reasons, contains only miniature trees. Pygmy forests may occur over various world locations with notable occurrences being noted in the literature of the: California coastal terraces and inner coastal mountains of Northern...
. The Stora Alvaret, sometimes called the Great Alvar, is a dagger
Dagger
A dagger is a fighting knife with a sharp point designed or capable of being used as a thrusting or stabbing weapon. The design dates to human prehistory, and daggers have been used throughout human experience to the modern day in close combat confrontations...
shaped expanse almost 40 kilometres (24.9 mi) long and about 10 kilometres (6.2 mi) at the widest north end.
Geological origins
The limestone plain was created by glacialGlacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
action from earlier ice age advances. The limestone formation itself was created about 500 million years ago in more southerly seas. Gradually hardening into limestone and drifting northward, the limestone of the Stora Alvaret contains a rich fossil record of some of the marine creatures who contributed to it. For example, orthoceratites are found in some of the present day structures on the island.
Only as recently as 11,000 years ago did the first portions of the island of Öland emerge from the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
, after the overpressure of the last glaciers was relieved by melting. Over the next several thousand years, more ice melted and the first wave of large mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s including human
Human
Humans are the only living species in the Homo genus...
s migrated across the ice bridge
Ice bridge
An ice bridge is a frozen natural structure formed over seas, bays, rivers or lake surfaces. They facilitate migration of animals or people over a water body that was previously uncrossable by terrestrial animals, including humans. The most significant ice bridges are formed by glaciation, spanning...
from the mainland. Finally a thin soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
mantle (only two centimeters at the deepest) was formed by plant colonisation of the bare limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
and some wind driven deposition, to create the alvar
Alvar
An alvar is a biological environment based on a limestone plain with thin or no soil and, as a result, sparse vegetation. It is also known as a pavement barren although this term is also used for similar landforms based on sandstone. In the United Kingdom the exposed landform is called a limestone...
formation of the present. In many places the limestone has no soil whatsoever upon it.
Prehistoric man
Alby, Öland
Alby is a village on the Baltic Sea in the Hulterstad district at the western fringe of the Stora Alvaret. Archaeological evidence indicates this settlement to have been one of the oldest on the island of Öland, with excavations, dating to the paleolithic era, showing the presence of...
, situated on the east coast of the island, where excavations have revealed vestiges of wooden huts around a prehistoric lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
. Artefacts retrieved include evidence of bear
Bear
Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...
, marten
Marten
The martens constitute the genus Martes within the subfamily Mustelinae, in family Mustelidae.-Description:Martens are slender, agile animals, adapted to living in taigas, and are found in coniferous and northern deciduous forests across the northern hemisphere. They have bushy tails, and large...
, seal
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
and porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
, but also reveal hunting and gathering technologies through discovery of bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
spear
Spear
A spear is a pole weapon consisting of a shaft, usually of wood, with a pointed head.The head may be simply the sharpened end of the shaft itself, as is the case with bamboo spears, or it may be made of a more durable material fastened to the shaft, such as flint, obsidian, iron, steel or...
s, elk
Moose
The moose or Eurasian elk is the largest extant species in the deer family. Moose are distinguished by the palmate antlers of the males; other members of the family have antlers with a dendritic configuration...
antler
Antler
Antlers are the usually large, branching bony appendages on the heads of most deer species.-Etymology:Antler originally meant the lowest tine, the "brow tine"...
harpoon
Harpoon
A harpoon is a long spear-like instrument used in fishing to catch fish or large marine mammals such as whales. It accomplishes this task by impaling the target animal, allowing the fishermen to use a rope or chain attached to the butt of the projectile to catch the animal...
s and flint
Flint
Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark grey, black, green, white, or brown in colour, and...
.
Evidence of later ringfort
Ringfort
Ringforts are circular fortified settlements that were mostly built during the Iron Age , although some were built as late as the Early Middle Ages . They are found in Northern Europe, especially in Ireland...
s abounds including the most well known site at Eketorp
Eketorp
Eketorp is an Iron Age fort in southeastern Öland, Sweden, which was extensively reconstructed and enlarged in the Middle Ages. Throughout the ages the fortification has served a variety of somewhat differing uses: from defensive ringfort, to medieval safe haven and thence a cavalry garrison...
. In the Bronze Age
Bronze Age
The Bronze Age is a period characterized by the use of copper and its alloy bronze as the chief hard materials in the manufacture of some implements and weapons. Chronologically, it stands between the Stone Age and Iron Age...
and early part of the Iron Age
Iron Age
The Iron Age is the archaeological period generally occurring after the Bronze Age, marked by the prevalent use of iron. The early period of the age is characterized by the widespread use of iron or steel. The adoption of such material coincided with other changes in society, including differing...
, extreme pressure was exerted on the limited tree species growing on the Stora Alvaret and its margins. Jannson suggests that this disappearance of trees
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
caused a mysterious evaporation of humans about 500 AD which is documented at Eketorp and other sites. It is thought provoking to imagine that the expanded human population
Overpopulation
Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. The term often refers to the relationship between the human population and its environment, the Earth...
may have exceeded its carrying capacity
Carrying capacity
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment...
of this place by about 500 AD. Later, about 800 to 1000 AD various Viking
Viking
The term Viking is customarily used to refer to the Norse explorers, warriors, merchants, and pirates who raided, traded, explored and settled in wide areas of Europe, Asia and the North Atlantic islands from the late 8th to the mid-11th century.These Norsemen used their famed longships to...
settlements appeared on the fringe of the Stora Alvaret.
Ecology
Biota (ecology)
Biota are the total collection of organisms of a geographic region or a time period, from local geographic scales and instantaneous temporal scales all the way up to whole-planet and whole-timescale spatiotemporal scales. The biota of the Earth lives in the biosphere.-See...
of the Stora Alvaret occurred in the year 1741 with the visit of Linnaeus. He wrote of this unusual ecosystem: "It is noteworthy how some plants are able to thrive on the driest and most barren places of the alvar". Some relict
Relict
A relict is a surviving remnant of a natural phenomenon.* In biology a relict is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas....
species from the glacial age are among the flora
Flora
Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...
palette of the Stora Alvaret. A wide variety of wildflower
Wildflower
A wildflower is a flower that grows wild, meaning it was not intentionally seeded or planted. Yet "wildflower" meadows of a few mixed species are sold in seed packets. The term "wildflower" has been made vague by commercial seedsmen who are interested in selling more flowers or seeds more...
s and other plants are found on the limestone pavement ecosystem. Some of the species found include stonecrop, dropwort
Dropwort
Dropwort , also known as Fern-leaf Dropwort, is a perennial herb of the family Rosaceae closely related to Meadowsweet...
, Artemisia
Artemisia (plant)
Artemisia is a large, diverse genus of plants with between 200 to 400 species belonging to the daisy family Asteraceae. It comprises hardy herbs and shrubs known for their volatile oils. They grow in temperate climates of the Northern Hemisphere and Southern Hemisphere, usually in dry or semi-dry...
oelandica (endemic to Öland), Shrubby Cinquefoil
Shrubby Cinquefoil
Dasiphora fruticosa is a shrub in the family Rosaceae, native to the cool temperate to subarctic regions of the Northern Hemisphere, often growing at high altitudes in mountains.It is a deciduous, much branched flowering shrub growing to 0.1–1 m tall, rarely up to 1.5 m...
, Common spotted orchid
Common spotted orchid
The Common Spotted-orchid is acommonly occurring species of European orchid. It is widely variable in colour and height, ranging from 15 to 60 cm in height. The flower colour can vary from white to pale purple with purple spots. The lip has three lobes...
and kidney vetch. Most of these wildflowers bloom from May to July.
Numerous grasses are found on this alvar including Meadow Oat-grass
Arrhenatherum
Arrhenatherum, commonly called Oat-grass or Button-grass, is a genus with seven species and subspecies from the grass family Poaceae. It grows in Europe and the Mediterranean. Wild forms resemble Wild Oat or Fescue...
and Sheep's Fescue
Sheep's Fescue
Sheep's Fescue or Sheep Fescue is a species of grass.-General Description:It is a perennial plant sometimes found in acidic ground, for example in the Portlethen Moss, Scotland and mountain pasture, throughout Europe and eastwards across much of Asia; it has also been introduced to North...
; as would be expected from the occurrence of orchids, many fungi grow on the Stora Alvaret such as Hygrocybe
Hygrocybe
Hygrocybe is a genus of agarics in the family Hygrophoraceae. Called "waxcaps" in English , basidiocarps are often brightly coloured and have waxy to slimy caps, white spores, and smooth, ringless stems...
persistens and Lepiota
Lepiota
Lepiota is a genus of gilled mushrooms in the family Agaricaceae. All Lepiota species are ground-dwelling saprotrophs with a preference for rich, calcareous soils. Basidiocarps are agaricoid with whitish spores, typically with scaly caps and a ring on the stem. Around 400 species of Lepiota are...
alba. Although the alvar here is known for its severely dry conditions, there are some seasonal wetlands and vernal pool
Vernal pool
Vernal pools, also called vernal ponds or ephemeral pools, are temporary pools of water. They are usually devoid of fish, and thus allow the safe development of natal amphibian and insect species...
s, notably the vestigial lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
area northwest of the village
Village
A village is a clustered human settlement or community, larger than a hamlet with the population ranging from a few hundred to a few thousand , Though often located in rural areas, the term urban village is also applied to certain urban neighbourhoods, such as the West Village in Manhattan, New...
of Alby.
Practical logistics
The Stora Alvaret is bounded on the east, west and south by the perimeterPerimeter
A perimeter is a path that surrounds an area. The word comes from the Greek peri and meter . The term may be used either for the path or its length - it can be thought of as the length of the outline of a shape. The perimeter of a circular area is called circumference.- Practical uses :Calculating...
public two-lane highway
Highway
A highway is any public road. In American English, the term is common and almost always designates major roads. In British English, the term designates any road open to the public. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a...
which circumnavigates the entire island. At several latitudes there are less improved roadways that run east-west and intrude directly through the Stora Alvaret. Small villages such as Stora Vickleby, Gettlinge, Grönhögen, Hulterstad, Alby, Triberga and Vället lie at the fringe of the Stora Alvaret along the perimeter highway. There are fewer and smaller villages within the alvar expanse itself: Mockelmossen, Solberga and Flisas, for example. Some of the old villages are totally deserted such as Dröstorp. At the extreme south end of the Stora Alvaret lies Ottenby
Ottenby
Ottenby is a nature reserve at the southern tip of the island of Öland in Sweden. Ottenby was previously a royal game reserve stocked with fallow deer, and King Charles X Gustav of Sweden built a drystone wall to confine the native deer...
, a historic royal game farm and now a nature reserve
Nature reserve
A nature reserve is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research...
.
See also
- AlvarAlvarAn alvar is a biological environment based on a limestone plain with thin or no soil and, as a result, sparse vegetation. It is also known as a pavement barren although this term is also used for similar landforms based on sandstone. In the United Kingdom the exposed landform is called a limestone...
- EketorpEketorpEketorp is an Iron Age fort in southeastern Öland, Sweden, which was extensively reconstructed and enlarged in the Middle Ages. Throughout the ages the fortification has served a variety of somewhat differing uses: from defensive ringfort, to medieval safe haven and thence a cavalry garrison...
- Stone AgeStone AgeThe Stone Age is a broad prehistoric period, lasting about 2.5 million years , during which humans and their predecessor species in the genus Homo, as well as the earlier partly contemporary genera Australopithecus and Paranthropus, widely used exclusively stone as their hard material in the...
- WindmillWindmillA windmill is a machine which converts the energy of wind into rotational energy by means of vanes called sails or blades. Originally windmills were developed for milling grain for food production. In the course of history the windmill was adapted to many other industrial uses. An important...