Editing Geography of Norway (section)

===Boreal===
[[File:Swamp landscape in Signaldalen with Otertinden 2, 2012 June.jpg|thumb|Bogs and lakes are common in the boreal zone: Signaldalen in [[Storfjord Municipality]] with Otertind mountain.]]

Boreal species are adapted to a long and cold winter, and most of these species can tolerate colder winter temperatures than winters in most of Norway. Thus they are distinguished by their need for [[growing season]] length and summer warmth. [[Bog]]s are common in the boreal zone, with the largest areas in the North and Middle Boreal Zones, as well as in the area just above the tree line. The large boreal zone is usually divided into three subzones: South Boreal, Middle Boreal, and North Boreal.{{Cn|date=December 2023}}

The boreal zones in Norway belong to three ecoregions. The area dominated by spruce forests (some birch, pine, willow, aspen) mostly belong to the [[Scandinavian and Russian taiga]] ecoregion (PA0608). The [[Scandinavian coastal conifer forests]] ecoregion (PA0520) in coastal areas with mild winters and frequent rainfall follows the coast from south of Stavanger north to southern Troms and includes both hemiboreal and boreal areas. Bordering the latter region is the [[Scandinavian Montane Birch forest and grasslands]] ecoregion (PA1110). This region seems to include both mountain areas with alpine tundra and lowland forests, essentially all the area outside the natural range of Norway spruce forests.<ref>{{cite web |url=https://www.google.com/maps/search/http:%2F%2Fglobalspecies.org%2Fkmlserver%2Fgetkml%2Fpa1110/data=!4m2!2m1!4b1?source=s_q&hl=en |title=Google Maps |website=Google Maps}}</ref> This ecoregion thus shows a very large range of climatic and environmental conditions, from the temperate forest along the fjords of Western Norway to the summit of [[Galdhøpiggen]], and northeast to the [[Varanger Peninsula]]. The area above the conifer treeline is made up of mountain birch ''Betula pubescens-czerepanovii'' (''fjellbjørkeskog''). The Scots pine reaches its altitudinal limit about {{convert|200|m}} lower than the mountain birch.

====South Boreal====
[[File:Lågendeltaet.jpg|thumb|[[Lågendeltaet]] in Lillehammer, south boreal zone.]]

The South Boreal zone (SB) is dominated by boreal species, especially [[Norway spruce]], and covers a total of 12% of the total land area. The SB is the only boreal zone with a few scattered—but well-developed—warmth-demanding broadleaf deciduous trees, such as [[European ash]] and [[oak]]. Several species in this zone need fairly warm summers (SB has 3–4 months with a mean 24-hr temperature of at least {{convert|10|C}}), and thus are very rare in the middle boreal zone. Some of the species not found further north are black alder, [[Humulus lupulus|hop]], [[Origanum vulgare|oregano]], and [[Viburnum opulus|guelder rose]]. This zone is found above the hemiboreal zone, up to {{convert|450|m}} amsl in [[Østlandet]] and {{convert|500|m}} in the most southern valleys. In the eastern valleys it reaches several hundred kilometers into Gudbrandsdal and Østerdal, and up to [[Lom Municipality]] and [[Skjåk Municipality]], in [[Ottadalen]]. Along the southwestern coast, the zone reaches an elevation of {{convert|400|m}} at the head of large fjords (such as in Lærdal), and about {{convert|300|m}} nearer to the coast. Norway spruce is lacking in [[Vestlandet]] ([[Voss Municipality]] is an exception). North of Ålesund, SB vegetation predominates in the lowland down to sea level, including islands such as [[Hitra (island)|Hitra]]. Most of the lowland in Trøndelag below {{convert|180|m}} elevation is SB, up to {{convert|300|m}} above sea level in inland valleys such as [[Gauldalen]] and [[Verdalen]], and up to {{convert|100|m}} in [[Namdalen]]. The coastal areas and some fjord areas further north—such as [[Nærøysund Municipality]] and [[Brønnøy Municipality]], and the best locations along the [[Helgeland]] coast—is SB north to the mouth of [[Ranfjord]], while inland areas north of [[Grong Municipality]] are dominated by Middle Boreal zone vegetation in the lowland. There are small isolated areas with SB vegetation further north, as in [[Bodø Municipality]] and [[Fauske Municipality]], the most northern location being a narrow strip along the northern shore of [[Ofotfjord]]; and the endemic Nordland-[[whitebeam]] only grows in [[Bindal Municipality]].<ref>{{cite web |url=http://www.miljostatus.no/nordland/tema/naturomrader/naturvern/verneomradene_i_nordland/verneomrader/reppen_naturreservat.htm |title=Reppen nature reserve |website=miljostatus.no |access-date=21 December 2006 |archive-url=https://web.archive.org/web/20090319000018/http://www.miljostatus.no/nordland/tema/naturomrader/naturvern/verneomradene_i_nordland/verneomrader/reppen_naturreservat.htm |archive-date=19 March 2009 |url-status=dead }}</ref> Agriculture in Norway, including [[grain]] cultivation, takes place mostly in the hemiboreal and SB zones.

====Middle Boreal====
{{Unsourced section|date=December 2023}}[[File:Elsfjord F.JPG|thumb|In most of Norway, the middle boreal zone is dominated by spruce forest, but with some agriculture as well. September in [[Elsfjord]], [[Vefsn Municipality]].]]

The typical closed-canopy forest of the Middle Boreal (MB) zone is dominated by boreal plant species. The MB vegetation covers a total of 20% of the total land area. Norway spruce is the dominant tree in large areas in the interior of Østlandet, Sørlandet, Trøndelag, and Helgeland and the MB and SB spruce forests are the commercially most important in Norway. Spruce does not grow naturally north of Saltfjell in mid-[[Nordland]] (the Siberian spruce variant occurs in the Pasvik valley), due to mountain ranges blocking their advance, but is often planted in MB areas further north for economic reasons, contributing to a different landscape. Birch is usually dominant in these northern areas; but pine, aspen, rowan, [[Prunus padus|bird cherry]] and grey alder are also common. This MB birch is often a cross between [[silver birch]] and [[downy birch]] and is taller ({{convert|6–12|m}}) than the birch growing near the tree line. Conifers will grow taller. Some alpine plants grow in the MB zone; nemoral species are rare. The [[understory]] (undergrowth) is usually well developed if the forest is not too dense. Many plants do not grow further north: grey alder, silver birch, [[Galium verum|yellow bedstraw]], [[Rubus idaeus|raspberry]], [[Artemisia vulgaris|mugwort]], and ''[[Myrica gale]]'' are examples of species in this zone that do not grow further north or higher up. MB is located at an altitude of {{convert|400–750|m}} in Østlandet, up to {{convert|800|m}} in the southern valleys, {{convert|300–600|m}} ({{convert|800|m}} at the head of the long fjords) on the southwest coast, and {{convert|180–450|m}} in Trøndelag ({{convert|700|m}} in the interior, as at Røros and [[Oppdal Municipality]]). Further north, MB is common in the lowland: up to {{convert|100|m}} above sea level in Lofoten and Vesterålen, {{convert|200|m}} at [[Narvik (town)|Narvik]], {{convert|100|m}} at Tromsø, {{convert|130–200|m}} in inland valleys in Troms, and the lowland at the head of [[Altafjord]] is the most northerly area of any size—small pockets exist at [[Porsanger Municipality]] and [[Sør-Varanger Municipality]]. This is usually the most northerly area with some farming activity, and [[barley]] was traditionally grown even as far north as [[Alta Municipality]].

====North Boreal====
[[File:Sand with pines.jpg|thumb|Road in the pine forest in [[Karasjok Municipality]]. The climate here has the greatest continentality and the coldest winters in Norway; north boreal zone.]]
[[File:Övre dividal anjajohka.jpg|thumb|North boreal forest in [[Øvre Dividal National Park]]; the autumn colored leaves of the mountain birch, which continue upslope, pine having reached its limit.]]

The North Boreal (NB) zone, (also known as open or sparse taiga) is the zone closest to the [[tree line]], bordering the alpine or polar area, and dominated by a harsh subarctic climate. There are at least 30 summer days with a mean temperature of {{convert|10|C}} or more, up to about two months. The trees grow very slowly and generally do not get very large. The forest is not as dense as further south or at lower altitudes and is known as the mountain forest (''Fjellskog''). The NB zone covers a total of 28% of the total land area of Norway, including almost half of Finnmark, where the mountain birch grows down to sea level. The lower part of this zone also has conifers, but the tree line in Norway is mostly formed by mountain birch, a subspecies of downy birch (subspecies ''czerepanovii''),<ref>{{cite journal |last=Taulavuori |first=K.M.J. |display-authors=etal |title=Dehardening of mountain birch (Betula pubescens ssp. czerepanovii) ecotypes at elevated winter temperatures |url=http://www.skogoglandskap.no/publikasjon/SF_3230_2800 |date=2004 |archive-url=https://web.archive.org/web/20110720024233/http://www.skogoglandskap.no/publikasjon/SF_3230_2800 |journal=[[New Phytologist]] |volume=162 |issue=2 |pages=427–436 |doi=10.1111/j.1469-8137.2004.01042.x |archive-date=20 July 2011 |via=[[Norwegian Forest and Landscape Institute]] |access-date=25 December 2019|doi-access=free }}</ref> which is not to be confused with [[dwarf birch]]). Spruce and pine make up the tree line in some mountain areas with a more continental climate. Alpine plants are common in this zone. The birch forest {{convert|1320|m}} above sea level at Sikilsdalshorn is the highest tree line in Norway, while a birch at 1,404 m ASL in Veodal, Jotunheimen, is the highest growing single tree.<ref>{{Cite web|url=https://www.nrk.no/innlandet/norges-hoyestvoksende-tre-skaper-bekymring-blant-forskere-1.14653798|title = Norges høyestvoksende tre skaper bekymring blant forskere|date = 18 August 2019}}</ref> The tree line is lower closer to the coast and in areas with lower mountains, due to cooler summers, more wind near mountain summits, and more snow in the winter (coastal mountains) leading to later snowmelt. The NB zone covers large areas at {{convert|750–950|m}} altitude in the interior of Østlandet; is {{convert|800–1200|m}} in the central mountain areas; but at the western coast the tree line is down to about {{convert|500|m}} above sea level, increasing significantly in the long fjords ({{convert|1100|m}} at the head of [[Sognefjord]]). Further north, large areas in the interior highlands or uplands of Trøndelag and North Norway are dominated by the NB zone, with the tree line at about {{convert|800|m}} amsl in the interior of Trøndelag, {{convert|600|m}} in [[Rana Municipality]], {{convert|500|m}} at Narvik, {{convert|400|m}} at Tromsø, {{convert|200|m}} at Kirkenes and {{convert|100|m}} at [[Hammerfest (town)|Hammerfest]] (only pockets in sheltered areas). The large [[Finnmarksvidda]] plateau is at an altitude placing it almost exactly at the tree line. The last patch of NB zone gives way to tundra at sea level about {{convert|10|km}} south of the [[North Cape, Norway|North Cape]] plateau (near [[Skarsvåg]]). Areas south of this line are tundra-like with scattered patches of mountain birch woodland (forest tundra) and become alpine tundra even at minor elevations. The trees near the tree line are often bent by snow, wind, and growing-season frost; and their height is only {{convert|2–4|m}}. Outside Norway (and adjacent areas in Sweden), the only other areas in the world with the tree line mostly made up by a small-leaved deciduous tree such as birch—in contrast to conifers—are [[Iceland]] and the [[Kamtschatka peninsula]].

The presence of a [[conifer]] tree line is sometimes used (''Barskoggrense'') to divide this zone into two subzones, as the conifers will usually not grow as high up as the mountain birch. Spruce and pine grow at nearly {{convert|1100|m}} above sea level in some areas of Jotunheimen, down to {{Convert|400|m|feet}} in Bergen ({{Convert|900|m}} at the head of Sognefjord), {{Convert|900|m}} at Lillehammer (mountains near Oslo are too low to have a tree line), {{Convert|500|m}} at Trondheim ({{Convert|750|m}} at Oppdal), {{Convert|350|m}} at Narvik, {{Convert|200|m}} at Harstad, {{Convert|250|m|feet}} at Alta; and the most northerly pine forest in the world is in [[Stabbursdalen National Park]] in [[Porsanger Municipality]]. There are some forests in this part of the NB zone; and some conifers can grow quite large even if growth is slow.