Färnebofjärden National Park () is a Swedish national park traversed by the river Dalälven, about north of Stockholm. It covers , of which aquatic, on the frontier between the counties of Dalarna and Gävleborg.
After the retreat of the ice sheet that covered the region after the last ice age, the river found itself rerouted by an esker onto a plain uniquely ribbed by the ridges of other eskers, where it formed a succession of rapids and wide bays (called fjärdar), which the river inundates during the spring floods. This particular hydrography, along with the park's proximity to the ecological frontier between the north and the south, has favored the development of a fauna and flora of great biodiversity. The park possesses coniferous, mixed, and broadleaf forests, some of which quite ancient, spared by the logging industry because of their inaccessibility. These forests constitute the ideal environment for numerous species, in particular birds, with critical densities of woodpeckers and owls.
If the presence of humans was relatively discreet since the Stone Age, concentrated principally atop the eskers, the development of mining activity (in particular of iron) has profoundly affected the region. The forests were exploited to feed the water-powered forges which grew up along the river. One of the most important was that of Gysinge, founded in 1668 and situated right next to the park. In 1975, in reaction to the threat of the clearing of a vast forest, the movement for the creation of a national park began, culminating in the park's opening in 1998. The park was added to the Natura 2000 Network and included in the Ramsar Convention's list of wetlands.
The park and its environs are important tourist destinations. The river is its favored mode of discovery, but some hiking trails permit other explorations. The park is equally appreciated by fishing enthusiasts.
Toponymy The park takes its name from Färnebofjärden, which designates the entire section of the river between Tyttbo and Gysinge. The name means "fjärd of Färnebo". The Swedish word fjärd has the same etymology as the Norwegian word fjord, both of which Scandinavian words mean "an expanse of water in a channel". Most of the bodies of water called fjords in Norwegian were steep glacial valleys into which the sea had penetrated, which was the more restrictive definition which passed into French and English. The name Fjärnebo is the ancient name of the village of Österfärnebo ("East Färnebo"), situated near the park; its name changed in the 17th century to distinguish it from a Färnebo in Västmanland, which was itself rebaptized Västerfärnebo ("West Färnebo"). The name of the village means "habitation (bo) next to the fjärd of horsetails (fräken, which became Färne)".
Geography
Location and environs
The park straddles the municipalities of Sala in Västmanland County, Heby in Uppsala County, Avesta in Dalarna County, and Sandviken in Gävleborg County.p. 4 It contains a section of the Lower Dalälven, which since the Middle Ages has marked the frontier between Svealand and Norrland. The park's main entrance, at Gysinge, is about from the city of Uppsala and so about from Stockholm.
The park proper includes most of the fjärd of Färnebofjärden and the river's floodplain, as well as parts of the surrounding lowlands, for a total area of more than , of which are water. The only parts of the fjärd not included in the park are the peninsulas of Östa and Ista, since they are inhabited, but these are protected by nature reserves of and , respectively. In addition, the park is bordered by several additional preserves: at Hedesundafjärden, at Jordbärsmuren-Ålbo, and at Gysinge, for a combined area, with the park and peninsula reserves, of more than .
Terrain The terrain of the park is overall flat, with an altitude ranging from to below sea level.p. 11 Certain parts are nevertheless quite hilly, such as Torrösundet, Långvindsjön and the valleys of the Tiån and the Storån. In addition, the ridge Enköpingsåsen cuts across the park, with a maximum height of , crisscrossing the region over between Trosa to the south and Bollnäs to the north. This ridge spans the river and creates, among other land features, the isle of Sandön and the peninsula of Ista. The river has largely flooded this flat and irregular zone, creating a mosaic of water, dry earth, and wetlands. The park also includes several bays (Östaviken, Andersboviken, Edsviken, etc.) as well as 200 islands and skerries, the largest islands being Mattön, Torrön, Ängsön, Vedön, Rosön and Västerön.p. 12
Climate The park is situated in a continental climate (Dfb in the Köppen climate classification), with rain mostly in summer. It is situated on the climate frontier between north and south, which helps determine the Limes Norrlandicus marking the border between the north of Scandinavia and the south. The snow cover lasts a little over 3 months and the river is frozen during a similar period, with the exception of the rapids, which remain ice-free for most of the winter.
Hydrography
The park is situated along the course of the Dalälven, the second longest Swedish river at . The river begins at the confluence of the Västerdal River and the Österdal River in Gagnef Municipality. At Avesta, the river, which until then was trapped in a narrow valley, becomes the Lower Dalälven (), and large floodplains (called fjärdar) alternate with zones of rapids. Färnebofjärden is the first big floodplain of the Lower Dalälven, situated between the rapids of Tyttbo to the west and Gysinge and Sevedskvarn to the east.
At Gysinge, the river already has a watershed of , for an average flow of . While the flow of the river Österdalälven is controlled (at Trängslet and the lake Siljan), the course of the Västerdalälven is free, and thus has the largest seasonal variations. As a result, when it reaches the park, the river is still relatively little regulated, with a speed varying from to more than . It is, in particular, the sole fjärd with a mouth that remains unregulated. The regulation of the Österdalälven has all the same an impact upon Färnebofjärden, the great inundations of the plains during the spring floods being more rare, even if they are nevertheless capable of inundating several dozens of square kilometers.
Besides the Dalälven, there are many streams inside the park, which flow into the river. Among these, one can number the Lillån, the Storån, the Alderbäcken and the Tiån on the right (south) bank, and Bärreksån and Laggarboån along the right bank.p. 13 One can find also five small lakes inside the park, in particular around Tinäset. It is also near Tinäset that the principal bogs of the park, Lindebergsmossen and Svarviksmossen, are situated.p. 21 of the park are marshes and bogs, making up more than 20% of its total surface, and more than a third of the non-aquatic surface area of the park.p. 17
Geology
The bedrock of the park is of granite and granitic gneiss, and dates from the formation of the Svecofennids, a mountain chain formed between 1750 and 2500 million years ago. Subsequently, the area underwent a long period of erosion, so that by leading 600 million years ago the so-called Sub-Cambrian peneplain had formed.
During the last ice age, Sweden was covered with an ice sheet, which withdrew from the region about 10000 years ago.p. 33 The glacier left behind in the region many eskers and moraines, such as the esker Enköpingsåsen. When the glacier withdrew, the soil had been so compressed by its mass that the entire zone situated to the east of Avesta found itself at sea level. During this maritime period, sediments deposited themselves on the bedrock, which explains why that region even today has superior fertility to that of the rest of the country. It is the reason why the line of separation between the north and the south (the Limes Norrlandicus), which passes not far from the park, is so visible in the region: the zone to the north of the limes was not covered with these sediments.
When this sea, called the Littorina Sea, the ancestor of the Baltic Sea, withdrew, the Dalälven found itself blocked at Avesta by one of these eskers formed by the ice sheet: Badelundaåsen. In effect, before the ice age, the river continued in the direction of the Mälaren, in which it emptied itself and it so had flooded a valley along this entire section. Because of the fact of the presence of this obstacle, it was forced to head northeast. So, in the whole section of the Lower Dalälven, the river did not have the time to flood a true valley. It thus had to adapt itself to the topology of the terrain, forming large fjärds with many isles in the flattest sections and by contrast a course narrower and faster at the different eskers encountered along the way.p. 32
Natural environment
The park of Färnebofjärden is according to the classification of the WWF, situated in the terrestrial ecoregion of Sarmatic mixed forests, not far from the frontier of the Scandinavian and Russian taiga.
Plants
Almost all the types of forest of central Sweden are present in the park, which is due to both the presence of dry and wet environments and to the proximity of the Limes Norrlandicus line marking the frontier between the environments of the north and south.p. 6 This implies the presence in the park of environments and species characteristic to both the North and the South of Sweden. A great number of endangered species appear in the park: two species of vascular plants, 25 species of mosses, 34 species of lichens and 22 species of fungi.p. 31
The park presents different environments as regards flora, the principal being the forests of conifers ( making up 9.9% of the park), the mixed forests ( making up 14.5% of the park), of open bogs ( making up 16.3% of the park) and woods ( making up 5% of the park) and finally wetlands ( making up 7.4% of the park).
The forests of conifers, principally of Norway spruce, are in particular present in the south of the park, around Tinäset, on the isle of Torrön and the peninsula of Öbyhalvön.p. 18 These forests have not been logged since the 1950s and certain trees are themselves over 120 years old. These old trees as well as the presence of dead wood give this forest a very ancient appearance, and contribute to a great richness of lichens and fungi. The soil is often covered in moss, the characteristic species being Hylocomium splendens, but Anastrophyllum hellerianum and Nowellia curvifolia are also common.p. 19 One can also find European blueberries and lingonberries in the undergrowth.
In the zones most subject to inundations, conifers are more rare, since they do not like in general the wetter zones. In these forests, one can find broadleaf trees such as the aspen, very common in the Lower Dalälven, but rare in the rest of the country. These forests also have English oaks and small-leaved lindens and the wetter forests are mostly made up of alders, birch trees and willows.p. 20 The richness of these forests and in particular their undergrowth depends above all on the nature of the soil. The poorer soils grow blueberries, bog bilberries, wild rosemary and cloudberry, whereas the richer soils are home in particular to Lily of the valley, woodland strawberries, purple small-reed and yellow loosestrife.