Home Programme Description Study region Publications Publication: Ambio Special Issue 2015 People Calendarium
 

Ekoklim has two main study regions

The alpine tundra

The alpine tundra in north-western Sweden is the second study region of Ekoklim. The region is part of the Fennoscandian mountain range, where a combination of high latitudes and high altitudes creates subarctic climate conditions.


Climate change in the Arctic

The arctic tundra is found north of the boreal (taiga) forest line (Fig. 1). The average July temperature is generally below 10-12°C. The growing season is short while winters are long and cold. Since the early 20th century, the average rate of climate warming has been almost twice as high in the Arctic as in other parts of the Northern Hemisphere. This rapid change is predicted to continue, but with large regional variation in temperature trends as well as hydrological trends.

Climate change in the Arctic may impact the development of the global climate through a number of feedback mechanisms, e.g. changes in the uptake and emission of greenhouse gases and changes in hydrological circulation patterns where increased freshwater fluxes could change the thermohaline circulation. Within the Arctic, climate change is expected to have strong effects on the ecosystem. The Arctic biota is characterised by species adapted to harsh conditions, often at the expense of competitive ability. Hence, the Arctic biota is directly vulnerable to climate warming, but also to indirect effects of climate warming such as increased interactions with southern species which are predicted to expand their distribution in Arctic areas.

Ekoklim in the alpine tundra region

The Fennoscandian mountain range can be regarded as a southern extension of the Arctic tundra (Fig. 1), where the forest line is determined by altitude rather than latitude, and the alpine tundra is fragmented by forested valleys (Fig. 2, 3). Because of its southern location combined with high levels of fragmentation, we predict that changes already seen in response to climate change in Sweden will spread to other parts of the Arctic as climate change continues. Hence the alpine tundra in Sweden provides a potential model region for studies of climate change in tundra regions. Eventually, large parts of the alpine tundra in Sweden might be replaced by forest (Fig. 2) and forests are predicted to replace tundra regions globally.

Geology, hydrology, ecology and land use

The Fennoscandian mountain range is geologically old. The peaks are denudated and often have a rounded shape, while the wide valleys have been formed by glacial and fluvial processes. The ground is covered by relatively thin layers of glacial and glacifluvial deposits. The climate is generally maritime and moist because of the closeness to the Atlantic Ocean in the west. Warm, moist air from the sea is cooled down above the mountains and the suspended water is released as precipitation. Most parts of the mountain range receive large quantities of precipitation, but the local variation is substantial and some areas, particularly in the east, are relatively dry.

The highest peak in Sweden, Kebnekaise, rises 2102 m above sea level, but most peaks are lower. The forest line is located 600-950 m above sea level, depending on latitude (Fig. 3). The forest line is generally composed of birch. Common vegetation types above the forest line are grass and shrub heaths and fens (Fig. 3). The fauna includes several species typical for Arctic ecosystems such as reindeer (Rangifer tarandus), Norwegian lemming (Lemmus lemmus, Fig. 4), Arctic fox (Vulpes lagopus), ptarmigan (Lagopus muta), long-tailed skua (Stercorarius longicaudus) and Arctic char (Salvelinus alpinus).

All reindeer in Sweden are semi-domesticated, owned by reindeer herders among the indigenous Sami people. The reindeer are herded between the alpine tundra, which are used for grazing in summer, and wintering areas in the boreal forest. Reindeer herding has been carried out on a large-scale basis since the early 17th century. Other forms of land use in the alpine tundra are tourism, hunting and fishing.

Ongoing research

The alpine tundra has been a target of research by the hydrological research group as well as the Departments of Zoology and Botany at Stockholm University. Thus, Ekoklim will build new research on existing background data. The Ekoklim programme comprises, among other things, studies of climate and hydrology in tundra regions, and impacts of climate change on the tundra biota.

 
 

Fig 1. The distribution of arctic and alpine tundra in the northern hemisphere (left; in orange) and alpine tundra in Fennoscandia (right; in red)
 

Fig 2. Alpine tundra in Sweden at present (left; a). Predicted distribution of alpine tundra in year 2100 if there is a 100 m altitudinal advance in the tree line, which corresponds to a 0.6°C increase in temperature (middle; b). Distribution of alpine tundra in year 2100 according to a predicted climate scenario the temperature increases by 2.6-4°C which causes a tree line advance of 433-667m (right; c). The climate scenario in (b) is regarded as conservative, which implies that the climate scenario in (c) may be the one we should expect. In scenario (c), 85% of the tundra heaths would become forested, leaving primarily high peaks covered by boulder fields above the tree line.

(Figure after Moen, Aune, Edenius & Angerbjörn 2004 In: Ecology & Society 9:16)

 


Fig 3. Vegetation zones in the Swedish mountain range. The tree line is found approximately 950m above sea level in the south and 600-800m above sea level in the north. Most alpine plants and animals are found in low and middle alpine habitat, which is dominated by heaths and fens. The high alpine zone, located above 1600m a.s.l. in the south (1200m in the north), is dominated by boulder fields where few species can live.

(Figure following Andersson et al. 1985 Fjällens Vegetation. Naturvårdsverket.)

 


Fig 4. A Norwegian lemming - a species endemic
to the Fennoscandian mountain range.