Raet Protected Landscape
Arendal kommune, Aust-Agder
Raet Protected Landscape
Five methods for the protection of the area:
Raet (1)Protected Landscape, including the flora and fauna, was protected by Royal Decree on 15 December 2000. The pro- tected area stretches from, and includes, Jerkholmen in the west to Tromlingene in the east – a distance of about 15 kms. The protected area covers about 5,400 acres, of which about 4,600 acres is sea.
The aim of the protection is «to preserve the specific character of the natural landscape and the cultivated land with geological occurrences from the Quaternary period and distinctive animal and plant life linked with Raet in the coastal area of Aust-Agder».
There are three main criteria that form the basis for the protection of Raet Protected Landscape.
These are:
• sediments
• geomorphology
• fresh water dammed up by the moraine The many bare outcrops of rock shaped by glacial erosion that we find in the area are examples of geomorphological shapes.
These are bedrock bumps that have been ground smooth and fine on the stoss faces towards the ice and torn up on the lee faces.
Tromlingene
Jerkholmen
Lille Torungen
Store Torungen Gjesøya
Spornes Bjelland
Alvekilen
Hove
Halvors holmene
Tromøya
Merdø Hisøya
Havsøya Ærøya Gjervolds
øya
Galtesund
Tromøysund Arendal
Front page photo from Bjellandsskjær, Tromøy. Photo: Ove Hetland
Within the area there are three (2)nature reserves which is a «stricter» form of pro- tection than protected landscapes. These are not included in the protected landscape but act as «islands» in the protected lands- cape area. These three nature reserves are, from west to east, Indre Halvorsholmen, Store Torungen and the western part of Tromlingene. The first two are intended to take care of nesting seabirds and therefore no one is permitted to go ashore from 15 April to 15 July. The western part of Tromlingene is protected to preserve the wetlands. The eastern part of Tromlingene has so-called bird-life protection as a part of the protection regulations in Raet protected landscape.
On the outer edge of Tromøya the (3)forest was protected by a Forest Act as early as 1914, the purpose of this was to create shelter for the areas within. The forest is still protected, but it no longer has the same function as it had previously since large parts of Tromøya now have considerably more vegetation.
Within Raet Protected Landscape the following areas have been set aside for (4) outdoor recreational activities: from west to east – Jerkholmen, Skjelbergholmen, Flatskjær, Tvisteinen, Ærøya, parts of Havsøya, parts of Merdø, Hove and Spornes. Areas set aside for outdoor recreational activities are either owned by the government, the municipality or there are agreements between the government and private landowners, such as the (5) Coastal Park («Skjærgårdsparken»).
End moraine Raet
Raet – which is the name of the largest continuous end moraine in Scandinavia – is an end moraine after the last Ice Age, and is one of the criteria for the protection of the area. Raet moraine is an enormous gravel ridge that was deposited by advancing inland ice 10-11,000 years ago in one of the
final spasms of the Ice Age. Probably the glacial front of the inland ice towered like a steep wall in the sea, with proportions that are similar to those we find along the coasts of Antarctica and Greenland today. The ra moraine stretches from Finland, through Sweden, Østfold county in Norway and crosses the Oslofjord at Moss. In Vestfold county it comes to the surface at Horten and provides the fertile soil for the country’s largest beech forest Fagus sylvatica at Larvik, amongst other things. After that it disappears into the sea again at Mølen, but appears here and there as islands like Stråholmen and Jomfruland in the county of Telemark. In Aust-Agder county we first notice it in the east, just off Flosta, where the cobblestone island of Målen appears. After that we see the islands called Tromlingene, and it is here that Raet Protected
Landscape begins. We can clearly see the large amounts of boulders and cobbles- tones that the sea has washed out from the moraine material at Spornes outside Tromøy, on the outer side of Merdø and further west in the protected area on Jerkholmen, and on Målen. From here it appears on land at Hasseltangen, where again it is covered in beech forest, and can then be traced up to Feviktoppen, Grimstad, Birkenes and then onwards in a westerly direction. Raet, and similar end moraines in neighbouring countries, clearly illustrate the distribution of the inland ice at an important period when the ice surface was melting during the last Ice Age.
The moraine in the protected landscape was deposited entirely underwater. After the ice withdrew, the sea swamped low-lying land areas. Following that the glacio-isostatic uplift of the land gradually took place. The highest level of the sea after the last Ice Age is known as the marine border and in the Arendal area it reaches up to 65-70 metres above the present sea level. Tromlingene islands were raised above sea level 3-4,000 years ago, and Jerkholmen somewhat later.
Formation of the Ra. Illustr.: Ivar Johan Jansen
Today, the Ra moraine, which largely consists of silt and moraine material containing clay (moraine clay), has a layer of beach-washed material, partly with large blocks and cobblestones on the surface. Sandy marine beach deposits have settled over the fine grained sea deposits on both sides of the Ra. The characteristic glacially- shaped smooth whale-back rocks on the outside of the Ra form an effective barrier against continued erosion of the sediments.
Topography, Geology and Sediments The visible topography in the protected landscape area is relatively flat. Islands like Tromlingene (14 m above sea level), Jerkholmen (9 m above sea level) and Målen (about 2 m above sea level) consist mainly of sediments. However, if we dip down beneath the surface of the sea, the picture is rather different. There we see the highest ”mountains” of underwater reefs, sunken rocks and islands, whilst the largest
”valleys” form dark depths. Between Jerkholmen and Store Torungen we find some depths of 157 metres. Between Havsøya and Merdø there is also a distinct deep ”valley” that continues in Galtesund.
Raet Protected Landscape consists pre- dominantly of bedrock although there are local occurrences of diabase dikes.
Large amounts of sediments have been deposited. On the side facing the sea, waves have washed out the small particles over a very long period and therefore we find the coarsest material like cobblestone and large stone boulders on the surface.
Under the upper ”erosion skin” we find fine particles like sand, silt and clay that are only a metre or two beneath the surface. Also in the surf zones you can see a number of well-developed beach ridges of gravel and stone that today cover large areas of the moraine in this area. After several thousand years of vegetation that has deposited leaves, needles etc, a thin layer of humous has formed on the surface. In the lower-lying parts, damp and swampy areas have been formed. In addition to Botnetjern on Tromøy, we can find smaller occurrences of open freshwater on several of the smaller islands.
Climate and vegetation
Raet Protected Landscape lies far south in Norway and entirely in the beach area, part- ly under the sea and partly on land. The climate is typically governed by the ocean.
Throughout the protected landscape area
The advance and retreat of the front of the glacier has created smaller ridges parallell to the Ra-line. In post- glacial time, following the glacio-isostatic uplift of the land, the moraine was subject to erosion by the waves.
Surface material is sorted and moved around. Stones and blocks are washed out and cobblestone areas are formed.
In the Younger Dryas period between 11-10,600 before the present time, the front of the glacier advances to the Ra-line. Sediments on the sea bottom are pushed together and deposited, together with moraine materials that the ice carries with it, as an end moraine (Ra-mor- enen). The sea level is about 61 metres higher than today.
The Allerød period 11-12,000 years ago. The inland ice has receded and the border of the ice lies further in than the present-day coastline. The glacier has deposited scattered moraine deposits on the sea bottom, and in this period silt and clay from the sea are also deposited.
Sand and stones are dropped from passing icebergs.
Jerkholmen, or Jerken as it is known locally, is the only one of the islands in Raet Protected Landscape that exclusively consists of sediments. One can clearly see two large and several smaller burial mounds on the island, as well as two large hawthorn trees Crataegus monogyna. Photo: Ivar Johan Jansen
seaspray is driven in by the strong wind.
The proximity to the sea and the area’s relatively flat topography mean that it is oft- en windy. There is seldom much snow in the area. The sea modifies the temperature throughout the year so that the winters are relatively mild and summers are cool, even though Sørlandet is the district in Norway that has the most sunny days during the year.
Because Raet Protected Landscape lies so far south, you can find species that normally belong to more southerly latitudes, and that therefore have their northernmost boundary on the coast of Sørlandet.
When sailing ships previously travelled between the coast of Sørlandet and the continent they needed to maintain stability when returning without cargo, and this was
achieved by having a certain amount of weight placed in the bottom of the boat as ballast. Earth and other deposits were used for this purpose and in this way foreign plants and seeds were imported – known as ballast plants. Raet Protected Landscape has several species that have been imported like this.
Of the many botanical curiosities to be found we would mention the following: On Merdø there is a large holly tree Ilex aqui- folium growing in the thicket. This is further east than we usually find this species. On Tromlingene there is a large, round yew bush Taxus baccata. It stands in the midst of the cobblestones and neither looks like a yew nor grows at a place you would expect to find this plant. Also on Tromlingene interesting species like moschatel Adoxa moschatellina, greater tussock-sedge Carex
Harebells Campanula rotundifolia can be found on islands like Jerkholmen and Tromlingene, but are also present on large areas of the Protected Landscape. Photo: Ove Hetland
paniculata, common meadow-rue Thalictrum flavum and brooklime Veronica beccabunga can be found. One strange thing is the fantastic spring blossoming of thrift Armeria maritima on Tromlingene. Both on Lille Torungen and at Merdø one can see masses of beautiful, yellow, wild tulips Tulipa sylvestris flowering in the early spring. On Jerkholmen there are two monu- mental hawthorn trees Crataegus monogyna that are very noticeable. It is rare for hawthorn to grow into such large trees as we find here.
Animal life
Insects
This far south in Norway with its special flora, one can also expect to find exciting insects. A species of beetle new to Norway
was recently found on Sven Johnsen’s islets, just east of Jerkholmen.
On Tromlingene islands there are several plants that attract special species of butter- flies, and there are several southerly species that otherwise do not often occur in Norway.
It is particularly amongst the small butterfly species that we find the rarest types. On Jerkholmen and the nearby islets many old world swallowtail butterflies Papilio machaon can be seen. These butterflies are probably the largest and most beautiful butterflies we have here.
Amphibians and Reptiles
On the outer edges of the islands Merdø and Tromøya we have two locations with smooth newts Triturus vulgaris right on the edge of the beach. In stormy weather they
The geological occurrences from the Quaternary period are of great natural science and pedagogical value. The well- developed beach ridges and areas consisting of boulders and pebbles worn smooth by the action of the waves are particularly valuable. In the last-mentioned areas one finds rocks from almost everywhere in southern Norway. The photo shows Jerkholmen. Photo: Ove Hetland
are exposed to a great deal of salt water, which would normally be intolerable for these sensitive amphibians. We also find the same situation at Bjelland on Tromøya where there are several localities with smooth newts.
It is not known to what extent other amphi- bians such as frogs and toads have been observed in the protected landscape. When it comes to reptiles, one can expect to find species such as vipers Vipera berus, blindworm Anguis fragilis and grass snake Natrix natrix. Also the smooth snake Coronella austriaca can probably be found in the area.
Birds
Tromlingene islands and Jerkholmen are the two most important localities in the pro- tected landscape area for migratory birds.
OnTromlingene there are long muddy beaches that at low water constitute large areas, and these make Tromlingene Aust- Agder’s best migratory bird locality for wad- ing birds – but they are also important for many other species. A number of rare speci- es have been observed here, like: shovelers Anas clypeata, garganey Anas
querquedula, black-tailed godwits Limosa limosa, avocets Recurvirostra avosetta, spotted redshank Tringa erythropus, Sandwich terns Sterna sandvicensis and even Greater flamingo Phoenicopterus ruber.
Jerkholmen is situated furthest out in Sømskilen. Particularly in bad weather, Sømskilen is a resting place for large numbers of ducks, and many nest here. It also serves the function of a port of refuge for many species. Jerkholmen is the next best locality for migratory birds in the area.
Jerkholmen and Tromlingene islands are very similar, but Jerkholmen is smaller and does not have the same qualities when it comes to muddy beaches. Species that are typical for Jerkholmen are: linnets Carduelis cannabina, skylarks Alauda arvensis, com- mon gulls Larus canus, pipits Anthus, and during the late summer and autumn, large flocks of young starlings Sturnus vulgaris.
It is obvious that Jerkholmen is the county’s most certain locality to see short-eared owl Asio flammeus on autumn and spring migra- tion. Merdø is also an interesting island when it comes to birds. Many uncommon small bird species have been observed here and every year there are several nightin- gales Luscinia luscinia singing at Merdø.
Within the protected landscape area there are two seabird reserves: inner Halvorsholmen and the western part of Store Torungen with the adjacent islets and skerries. Store Torungen is one of the coun- ty’s best seabird reserves with big colonies of the larger gulls: herring gulls Larus argentatus, great black-backs Larus marinus and lesser black-backs Larus fuscus. Also common terns Sterna hirundo have had a colony here for a number of years, and the islands are also a refuge for many eider ducks Somateria mollissima.
Inner Halvorsholmen has nowhere near so many nesting birds as Store Torungen, but also here we find the large gulls nesting.
Probably this was the first nesting area for greylag geese Anser anser in recent times in Aust Agder. In 1994 they were observed here with young. Previously there was a big colony of common terns.
The round yew tree Taxus baccata on Tromlingene appears to grow right out of the cobblestones. There is probably boulder clay just beneath the rocks.
Photo: Ove Hetland
There are several places on Merdø and on the outer edge of Tromøya where smooth newts Triturus vulgaris can be found. Photo: Arild Pfaff
Havsøya is a holiday paradise with its small houses characteristic of the south coast of Norway.
Photo: Ove Hetland
The well-known local author, Gabriel Scott, used words like "eerie, shadowy twilight, cloaked in mist, ghostly foot- steps" to describe the evening mood on Tromlingene. Photo: Arvid Johnsen
Mammals
85% of Raet Protected Landscape consists of ocean and this limits the amount of land- based mammals. Roe deer Capreolus capreolus, hare Lepus europeaus, badgers Meles meles and mink Mustela vison are amongst the most common of the larger species. In addition we also find varying numbers and types of small rodents on the large, grassy islands like Tromlingene and Jerkholmen. Bats Chiroptera can also be seen in the area and presumably there are several different species. Previously hedge- hogs Erinaceous europaeus and red foxes Canus vulpes were also seen in the district, but it is uncertain whether these species are still here. On Jerkholmen and Tromlingene sheep graze, and this contributes to limiting the vegetation so that the landscape is more open.
Whale and seal are two types of marine mammals that sometimes visit the area but no permanent occurrences are known. It is primarily the common seal Phoca vitalina that is the principal seal type in this area – not least at Jerkholmen in Sømskilen. Pilot whales Globiocephala melaena are occas- ionally sighted, but more frequently porpois- es Phocaena communis, the small whale species, are registered in the area.
Traditional use of Raet Protected Landscape
Historical sites
There are more than 135 occurrences of historical sites, stone burial mounds, pavements, parapets, foundations and excavations registered in the landscape area. These are from 1800 BC up to AD
1000. Of these there are 49 certain historical sites, and those on Jerkholmen and
Tromlingene islands are of high priority in a national perspective.
In the olden days it was common to bury the dead in monumental stone burial mounds at the highest point in the landscape. The dead should be positioned so they could both see and be seen, and therefore a view over the ocean was decisive when selecting the spot. It was the district’s most powerful persons who were honoured with burial in such mounds. The bodies were dressed in their finest clothes including jewellery and other possessions. Frequently the burial gifts were later stolen by grave robbers. The burial cists were placed directly on the rock in the middle of the burial mound and these were often built of flat slabs of stone. In addition to the large and easily seen burial mounds on Jerkholmen and Tromlingene, there are a number of smaller and less conspicuous burial mounds and barrows in the protected landscape area.
Cultural heritage
The clusters of buildings at Brekka, Lia and Bjelland on Tromøy, as well as those we find
on Merdø and Haysøya are particularly important. They include characteristic house types. It is worth mentioning that there are also remains of buildings and other constructions from the Second World War.
Cultural landscape
The countryside along Raet Protected Landscape has been marked by human activity in the area for generations.
Descriptions from Hove farm in the 1770s give us a picture of what the area looked like then. The landscape has become increasingly overgrown compared with the grazing pastures at that time. In about 1790, Merdø was an open landscape clearly marked by human activity. The yew tree on Tromlingene, the holly on Merdø and the hawthorn on Jerkholmen tell us about a period when the cultivated countryside was used differently than it is today.
Outdoor recreational activities Ever since the early 1900s outdoor
recreational activities have been popular in the Hove area. Today the entire coastal area of Sørlandet is very popular throughout the summer months, and islands like Jerk- holmen, Tjuvholmen, Ærøya, Havsøya, Merdø, Gjessøya and Tromlingene are particularly attractive and visited by many people. Seabird hunting, fishing and the
A few pairs of Shelduck Tadorna tadorna are to be found in the Protected Landscape. Photo: Ove Hetland
Honeysuckle Lonicera periclymenumis the flower for the County of Aust-Agder. Photo: Ove Hetland
The entire coast of southern Norway is much used for boating activities, particularly in the summer. Raet Protected Landscape has many south coast idylls which encourage outdoor recreation. Photo: Arild Pfaff
placement of fish traps and crab and lobster pots are activities that increase during the autumn and early winter. Areas like Hove and Spornes on the outside of Tromøy are popular walking areas also during autumn and winter. When the worst autumn storms are raging, the view is spectacular on these extremely exposed cobblestone beaches.
Pollen tests that have been carried out on the islands of Tromlingene indicate that grazing has pretty well taken place during the entire period there has been vegetation on the islands.
Take care of Raet Protected Landscape
• Disturbance or removal of any boulders, rocks or shingle from the area is pro hibited. These must not be moved for any purpose, since they are a part of Raet Protected Landscape. They must not be moved around to create sun traps, wind shields, sculptures or anything else.
• There are several large, impressive cultural memorials consisting of stone burial mounds in the area. These tell us about the culture and religion of our ancestors. We emphasize that historical sites and cultural memorials formed prior to 1537 are automatically protected by law. We request that these stones remain where they are.
• Take care not to place discardable bar becues on the bare rock or grass as this can cause permanent damage, and please remember to take discardable bar becues with you after use! Bonfires also cause permanent damage to the bare rock or grass and must therefore be placed in suitable areas, for example on sand, gravel or pebbles or sites that have previously been used.
• If you find birds’ nests or animals’ dens, do not pause for too long to observe these. It is best to look whilst keeping on
the move. Lengthy stops disturb the birds and animals. In addition the watchful eyes of species that eat eggs and young birds and animals – for example crows Corvus corone, magpies Pica pica and mink - often watch our movements and inspect the places where we have stopped. If the nervous behaviour of adult birds or animals causes you to suspect that you have stopped near nests or young animals, you must move on to another site.
• Never throw litter in the countryside, but please take home with you any rubbish you might find in Raet ProtectedLandscape!
• As a rule of thumb: Leave the area in the same condition as you found it – or better!
Rules for behaviour and management
You are welcome to visit Raet Protected Landscape, but bear in mind the following regulations, which are an extract from the protection regulations:
The area is protected against encroach- ment and activities which may alter the natural conditions of the landscape.
Motorized traffic in isolated areas is for- bidden, as is the parking of caravans.
Plant communities in the shore area, including the seashore and meadows, are protected against all forms of damage and destruction.
In the eastern part of Tromlingene the birds and their nests, eggs and young are protected against all forms of destruction and unnecessary disturbance.
Hunting, trapping and the use of firearms is for-
bidden. Dogs must be kept on a leash.
Generally, hunting and fishing is permitted in the Protected Landscape in accordance with prevailing regulations.
The County Governor in Aust-Agder is responsible for the management of Raet Protected Landscape.
There is frequent supervision in Raet Protected Landscape.
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Fylkesmannen i Aust-Agder miljøvernavdelingen Serviceboks 606 NO-4809 ARENDAL Telephone: +4737 01 75 53 Additional information concerning the
protected areas and the protection regulations can be obtained from:
Denne informasjonen er utarbeidet i 2001 av: Arild Pfaff Biologiske Undersøkelser.
Fylkesmannen i Aust-Agder would like to thank Margaret Gulbrandsen for translating the brochure into English.
