Trehörningen is a small lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 located in the municipality Huddinge in southern Stockholm

Stockholm

Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

, 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....

. As part of the Tyresån lake system, Trehörningen receives water from Lake Gömmaren and supplies water to Lake Ågesta

Ågestasjön

- External links :...

.

History

The area surrounding Trehörningen, Orlången

Orlången

Orlången is a lake in central Huddinge Municipality, just south of Stockholm, Sweden.Orlången, one of the lakes in the Tyresån Lake System, forms part of the Orlången Nature Reserve.- Catchment area :...

 and Ågestasjön

Ågestasjön

- External links :...

, is a fine example of a historical landscape evolving from a prehistoric settlement into a traditional agricultural village discontinued in the 19th century, encompassing structures from all interjacent eras. It is one of the few areas in Stockholm which escaped the creation of the widespread 20th century suburbs around the historical city of Stockholm, and, consequently, the area is considered as having cultural and historical values of national interest. The landscape include open cultivated and grazed fields next to steep rocks, pine and deciduous forests. Several grave fields, hillforts, and other archaeological structures, reflects the area was connected to 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...

 in prehistoric times. During medieval times, the area contained the only farmstead exempt from land dues (i.e. owned by a member of the Swedish nobility

Swedish nobility

The Swedish nobility were historically a legally and/or socially privileged class in Sweden, part of the so-called frälse . Today, the nobility is still very much a part of Swedish society but they do not maintain many of their former privileges...

) in Huddinge. In the area traces from the Stone age

Stone Age

The 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...

 and some cairn

Cairn

Cairn is a term used mainly in the English-speaking world for a man-made pile of stones. It comes from the or . Cairns are found all over the world in uplands, on moorland, on mountaintops, near waterways and on sea cliffs, and also in barren desert and tundra areas...

s from 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...

 have been found, and parts of the present road network is left unaltered for thousands of years.

Catchment area

Three fourth of the catchment area is used for settlements, including the commercial centre of Huddinge (Huddinge Centrum) and half a dozen residential neighbourhoods. Nevertheless, the shores of the lakes are of significant recreational importance as they border the Orlången Nature Reserve

Orlången Nature Reserve

Orlången Nature Reserve is a nature reserve surrounding Lake Orlången in central Huddinge Municipality, south of Stockholm, Sweden.There are four lakes within the reserve: Trehörningen , Ågestasjön, Orlången, and Mörtsjön....

 and contain several cliffs popular for bathing and angling. Both major inflows, Fullerstaån and Solfagradiket, are guided through culverts under neighbouring settlements, but reaches the lake through open ditches. Today, motor-driven boats are not permitted on the lake and restrictions are imposed on angling.

Environmental influence

The lake used to receive waste water from both settlements and other neighbouring operations 1951-1971, but the inflow is today reduced to stormwater

Stormwater

Stormwater is water that originates during precipitation events. It may also be used to apply to water that originates with snowmelt that enters the stormwater system...

 - the old usage still echoing in oxygen depletion and phosphorus

Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

 release at the lake bottom, and algae bloom and limited water transparency. To restrict future influence to a minimum, reduction in incoming flows are given priority rather than any actions to the lake itself. The lake was drudged in 1975-76, the product of which was pumped over to the lake's western bay where embankments prevents it from pouring back into the lake. Additionally, reed bed

Reed bed

Reed beds are natural habitats found in floodplains, waterlogged depressions andestuaries. Reed beds are part of a succession from young reed colonising open water or wet ground through a gradation of increasingly dry ground...

s were removed and other measures were taken to clean the lake. Vegetation has been cleared annually since.

Flora and fauna

As a locale for birds, the lake was significantly deteriorated by the mid 1970s drudging which caused a colony of Black-headed Gull

Black-headed Gull

The Black-headed Gull is a small gull which breeds in much of Europe and Asia, and also in coastal eastern Canada. Most of the population is migratory, wintering further south, but some birds in the milder westernmost areas of Europe are resident...

 to disappear. Today, the lake has a regular presence of Mallard

Mallard

The Mallard , or Wild Duck , is a dabbling duck which breeds throughout the temperate and subtropical Americas, Europe, Asia, and North Africa, and has been introduced to New Zealand and Australia....

, Eurasian Coot

Eurasian Coot

The Eurasian Coot, Fulica atra, also known as Coot, is a member of the rail and crake bird family, the Rallidae. The Australian subspecies is known as the Australian Coot.-Distribution:...

, Great Crested Grebe

Great Crested Grebe

The Great Crested Grebe is a member of the grebe family of water birds.- Description :The Great Crested Grebe is long with a wingspan. It is an excellent swimmer and diver, and pursues its fish prey underwater. The adults are unmistakable in summer with head and neck decorations...

, Common Goldeneye

Common Goldeneye

The Common Goldeneye is a medium-sized sea duck of the genus Bucephala, the goldeneyes. Their closest relative is the similar Barrow's Goldeneye....

; regular visits of Common Gull

Common Gull

The Common Gull or Mew Gull Larus canus is a medium-sized gull which breeds in northern Asia, northern Europe and northwestern North America. It migrates further south in winter...

, Heron

Ardea (genus)

Ardea is a genus of herons. Linnaeus named this genus as the Great Herons, referring to the generally large size of these birds, typically 80–100 cm or more in length....

, Common Merganser

Common Merganser

The Common Merganser or Goosander Mergus merganser is a large duck, of rivers and lakes of forested areas of Europe, northern and central Asia, and North America. It eats fish and nests in holes in trees...

, Osprey

Osprey

The Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...

, Marsh Warbler

Marsh Warbler

The Marsh Warbler, Acrocephalus palustris, is an Old World warbler currently classified in the family Acrocephalidae. It breeds in temperate Europe and western Asia and winters mainly in south east Africa...

, Great Reed-Warbler, and Grasshopper Warbler

Grasshopper Warbler

The Grasshopper Warbler, Locustella naevia, is an Old World warbler in the grass warbler genus Locustella. It breeds across much of temperate Europe and Asia. It is migratory, wintering from northwest Africa to India....

; and some uncommon guests such as Common Kingfisher and Black-throated Diver

Black-throated Diver

The Black-throated Loon is a migratory aquatic bird found in the northern hemisphere. The species is known as an Arctic Loon in North America and the Black-throated Diver in Eurasia, its current name is a compromise proposed by the International Ornithological Committee.-Taxonomy:The...

; the lake itself thus still being of ornithological

Ornithology

Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds...

 interest, while the forests surrounding the lake attracts Long-tailed Tit

Long-tailed Tit

The Long-tailed Tit or Long-tailed Bushtit is a common bird found throughout Europe and Asia. There are several extensive accounts of this species, most notably Cramp and Perrins, 1993; Gaston, 1973; and Harrap and Quinn, 1996...

 and Lesser Spotted Woodpecker

Lesser Spotted Woodpecker

The Lesser Spotted Woodpecker is a member of the woodpecker family Picidae. It is assigned to the genus Dendrocopos ....

.

Aquatic plant

Aquatic plant

Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...

s includes, except for Reed

Phragmites

Phragmites, the Common reed, is a large perennial grass found in wetlands throughout temperate and tropical regions of the world. Phragmites australis is sometimes regarded as the sole species of the genus Phragmites, though some botanists divide Phragmites australis into three or four species...

 and Club-rush

Schoenoplectus

Schoenoplectus is a genus of about 80 species of sedges with a cosmopolitan distribution. Note that the name bulrush is also applied to species in the unrelated genus Typha...

, several species of Duckweed

Lemna

Lemna is a genus of free-floating aquatic plants from the duckweed family. These rapidly-growing plants have found uses as a model system for studies in community ecology, basic plant biology, in ecotoxicology, in production of biopharmaceuticals, and as a source of animal feeds for agriculture...

, Chickenwort, and others. Along the shore are some 30 species of trees and plants, including Alder

Alder

Alder is the common name of a genus of flowering plants belonging to the birch family . The genus comprises about 30 species of monoecious trees and shrubs, few reaching large size, distributed throughout the North Temperate Zone and in the Americas along the Andes southwards to...

, Birch

Birch

Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...

, Aspen

Aspen

Populus section Populus, of the Populus genus, includes the aspen trees and the white poplar Populus alba. The five typical aspens are all native to cold regions with cool summers, in the north of the Northern Hemisphere, extending south at high altitudes in the mountains. The White Poplar, by...

, Spruce

Spruce

A spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...

, Sedges

Cyperaceae

Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...

, Loosestrife

Loosestrife

Loosestrife is the common name of a number of different flowering plants. The species belong to two taxonomic genera, Lythrum, within the family Lythraceae, and Lysimachia, within the family Primulaceae.Lythrum species known as loosestrife include:...

, Forget-me-nots

Myosotis scorpioides

Myosotis scorpioides , the Water Forget-me-not or True Forget-me-not, is a herbaceous perennial plant of the genus Myosotis. It is native to Europe and Asia and it can be found elsewhere, including much of North America, as an introduced species and sometimes a noxious weed. It grows in bogs and...

, Cinquefoils

Potentilla

Potentilla is the genus of typical cinquefoils, containing about 500 species of annual, biennial and perennial herbs in the rose family Rosaceae. They are generally Holarctic in distribution, though some may even be found in montane biomes of the New Guinea Highlands...

, and Water-pepper

Water-pepper

Water-pepper or Water pepper is a plant of the family Polygonaceae. It grows in damp places and shallow water. It is a cosmopolitan plant, found in Australia, New Zealand, temperate Asia, Europe, and North America...

.

Common Frog

Common Frog

The Common Frog, Rana temporaria also known as the European Common Frog or European Common Brown Frog is found throughout much of Europe as far north as well north of the Arctic Circle in Scandinavia and as far east as the Urals, except for most of Iberia, southern Italy, and the southern Balkans...

 and Common Toad

Common Toad

The common toad or European toad is an amphibian widespread throughout Europe, with the exception of Iceland, Ireland and some Mediterranean islands...

 have been observed by the lake, as have bat

Bat

Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...

s such as Northern Bat

Northern Bat

The Northern Bat is a species of bat. An adult Northern Bat has a body length of 4.9-6.6 cm, a tail of 3.2-5.1 cm, and a wing length of 4.1-5.1 cm. The species is found across Europe and Asia, from England to Hokkaidō and south to northern India.-References: 2006 IUCN Red List of Threatened...

 and Daubenton's Bat

Daubenton's bat

Daubenton's Bat, Myotis daubentonii, is a Eurasian bat with quite short ears. It ranges from Britain to Japan and is considered to be increasing its numbers in many areas.The name commemorates the French naturalist Louis-Jean-Marie Daubenton....

. No observations of Dragonflies

Odonata

Odonata is an order of insects, encompassing dragonflies and damselflies . The word dragonfly is also sometimes used to refer to all Odonata, but the back-formation odonate is a more correct English name for the group as a whole...

have been reported.