Terrestrial and freshwater ecosystems

Th e terrestrial and freshwater ecosystems of the Barents area cover 1.8 million km², with about 75% of this in Russia. Using the Barents Protected Area Network (BPAN) categorization for terrestrial areas there are fi ve main ecosystem types:

glacier, freshwater, open wetland, alpine and lowland tundra, and forest.

1 Th e Svalbard Archipelago is subject to a separate legal regime established by the 1920 Spitsbergen/Svalbard Treaty, which means that it constitutes a specifi c decision-making arrangement. Th e Treaty bestowed sovereignty over the islands to Norway, including responsibility for introducing non-discriminatory nature conservation measures, but at the same time it secured free commercial and scientifi c access for nationals and companies from other parties to the treaty. Th ere is an ongoing disagreement between Norway and some parties over whether the commercial rights guaranteed to other contracting states’ nationals on the basis of the Svalbard Treaty also apply to the EEZ on the continental shelf surrounding the islands. Th ese latter concepts have arisen decades aft er the treaty was adopted. One of the consequences of this disagreement is that a Fisheries Protection Zone was established around Svalbard, rather than an EEZ, with consequences for fi shing as well as potentially more broadly.

Figure 2.1 AACA Barents area.

Barents Sea Svalbard

Finnmark

Troms

Murmansk Lappland

Norrbotten

Oulu Karelia Västerbotten

Nordland

Arkhangelsk Komi

Yamalo-Nenets

Nenets

Major ocean currents warm cold

Barents Region political cooperative agreement area

2.2.1.1

Climate

The natural landscape and species present in the Barents area of today result mainly from the present climatic conditions combined with past events. For the whole of the northern hemisphere, ice-sheet advances during the Last Glacial Maximum played a significant role in forming the present landscape. Even though the extent and thickness of the ice cap are a subject of scientific discussion (Kullman, 2002; Birks et al., 2005), the period undoubtedly affected the Barents area. The lake-rich postglacial terrain is perhaps the most dominant feature in mainland areas, presenting a landscape with a lake density (number of lakes per 1000 km²) more than four times that of areas not previously covered by glaciers (Smith et al., 2007). The climate of the terrestrial areas within the Barents area is heavily influenced by proximity to the sea and its high latitude. The Gulf Stream also makes the entire region far warmer than comparable circumpolar areas at these latitudes, and mainland Norway, Sweden and Finland are regularly defined as sub-Arctic rather than Arctic. Present-day mean annual temperature (Figure 2.2), estimated for the period 1960–2015 (see Benestad et al., 2016 for data and gridding), ranges from about -18°C at Novaya Zemlya (Russia) to about 6°C on the west coast of Norway.

Temperature is estimated to have increased by 1–2°C over the period 1954–2003, with warming strongest in winter (ACIA, 2004). See Chapter 4 for further discussion.

Present-day mean annual total precipitation (Figure 2.2) estimated for the period 1960–2015 (see Benestad et al., 2016 for data and gridding) also demonstrates a gradient, from about 1700 mm on the Norwegian west coast to about 100 mm on Svalbard and Novaya Zemlya (Russia). Precipitation is estimated to have increased by 8% over the last century (ACIA, 2004). See Chapter 4 for further discussion of changes in precipitation.

Changes in winter climate, in particular winter warming events affect snow property. If followed by freezing temperatures the snow pack will increase in density and can generate ice layers in the snow. Such ice layers may limit access to forage by reindeer (Vikhamar-Schuler et al., 2016) as well as shelter and access to

food for small rodents living below the snow (Fuglei and Ims, 2008), thus affecting predators dependent on the rodents. See Chapter 4 for more discussion on snow.

2.2.1.2

Forest and tundra ecosystems

Forest/Taiga

The taiga (often referred to as boreal forest in the USA and Canada) constitutes the most widespread forest ecozone (Figure 2.3) in the Barents area, covering 54% of the land area on the mainland. It is bordered by Scandinavian coastal conifer forests (west), Scandinavian Montane birch forest and grasslands (northwest and upwards in the highlands and mountains), Kola Peninsula tundra (north), Northwest Russian-Novaya Zemlya tundra (northeast), Urals montane tundra and taiga (east) and Sarmatic mixed forests (south), and by the Baltic and White Seas.

The taiga summer is one to three months long with an average temperature of 10°C, although some areas, mainly in the west have a more humid continental climate with milder winters and longer summers. The mean annual temperature is generally between -5°C and 5°C, although actual temperatures may range from -54°C to 30°C. A typical winter day has a temperature of -20°C while a typical summer day has a temperature of 18°C.

Precipitation is relatively low throughout the year, generally 200–750 mm, but can reach 1000 mm in some areas, occurring mainly as rain during summer months, but also as fog and snow.

The flora comprises coniferous forests dominated by pine (Pinus sylvestris) in drier locations, often with an understory of juniper (Juniperus communis), spruce (Picea abies and P. obovata) and a significant mixture of birch (Betula pubescens and B. pendula). Siberian larch (Larix sibirica) is characteristic of the eastern parts of the ecozone. Besides birch, broadleaf trees of aspen (Populus tremula), willow (Salix spp.), and rowan (Sorbus aucuparia) also occur. Many smaller herbaceous plants grow on the forest floor, such as ferns, as

Figure 2.2 Present-day mean annual temperature (left) and mean annual total precipitation (right) estimated for the period 1960–2015. The data are based on station records from the European Climate Assessment & Dataset (ECA&D) project with methodology as per Benestad et al. (2016).

0

-200 200 400 600 800 1000 1200 1400 1600 18002000

-16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6

Precipitation, mm/y Temperature, °C

well as many diff erent types of berry, for example cranberry (Vaccinium oxycoccus), cloudberry (Rubus chamaemorus), blueberry (V. myrtillus) and cowberry (V. vitis-idaea), most of them surviving winter protected by the snow cover. Grasses grow wherever they can fi nd a patch of sun, and mosses and lichens thrive on the ground and on the sides of tree trunks.

Wildfi re and windfalls are important factors in the dynamics of the forests (Angelstam, 1998), opening up the canopy and enabling regeneration. Mixed in among the forests are bogs, fens, marshes, shallow lakes, rivers and wetlands, all of which hold vast amounts of water. Th e fl ora listed here are based on Olson et al. (2001) and https://en.wikipedia.org/

wiki/List_of_terrestrial_ecoregions (WWF), ‘Scandinavian and Russian taiga’.

Th e fauna is relatively low in species richness, but many species consider the taiga home for all or part of the year. Large herbivorous mammals are represented by reindeer (Rangifer tarandus), moose (Alces alces), red deer (Cervus elaphus) and roe deer (Capreolus capreolus). Smaller mammals are represented by the mountain hare (Lepus timidus) and rodent species such as beaver (Castor fi ber), squirrel (Sciurus vulgaris) and voles (Arvicolinae). Mammalian predators of the taiga include the (Eurasian) lynx (Lynx lynx), stoat (Mustela erminea), European otter (Lutra lutra), wolverine (Gulo gulo), gray wolf (Canis lupus), red fox (Vulpes vulpes), and brown bear (Ursus arctos). Th e fauna listed here are based on Hof et al. (2015), the Swedish Species Observation System (www.artportalen.se), and the Norwegian Species Observation Reporting System (www.

artsobservasjoner.no).

The taiga has environmental conditions that are too harsh for most reptiles and amphibians. However, the common European adder (Vipera berus) survives winter by hibernating underground, and the European common frog (Rana temporaria) may survive for months under ice. Adaptations to cold water and

the ability to survive under ice-covered water is a prerequisite for fish of the taiga. Examples of species that reside in the region are the northern pike (Esox lucius), grayling (Th ymallus thymallus) and trout (e.g. Salvelinus alpinus and Salmo trutta).

Th e largest animal group is the insects, which are important prey for mammals and birds and also function as pollinators and decomposers. Th e taiga is home to a few hundred bird species in summer, most of which take advantage of the long days and the abundance of insects. While many of these species leave as autumn arrives, carrion-feeders and large raptors such as the golden eagle (Aquila chrysaetos) and the raven (Corvus corax), stay behind in the southernmost parts of the taiga together with seed-eating birds such as ptarmigans (Lagopus spp.) and crossbills (Loxia spp.). About 1160 species of vascular plant, over 1000 lichens, 600 mosses, 36 mammals, 180 birds, and 19 diff erent freshwater fi sh have been documented in this ecozone.

Tundra

Alpine and Arctic tundra covers almost 20% of the area and is mainly present in Norway and Russia, situated north of the taiga belt in coastal areas of the north and west and in the High-Arctic archipelagos of Svalbard and Franz Josef Land. Th e area corresponds well with the Circumpolar Arctic Vegetation Map’s (CAVM Team, 2003) defi nition of the Arctic.

Th e tundra is oft en defi ned as a biome where tree growth is hindered by low temperatures and a short growing season. In this context the tundra is defi ned both from a latitudinal and an altitudinal perspective, both with the tree line as a border to other biomes further south or at lower altitudes. Nevertheless, scattered occurrences of trees can occur in tundra. Moderating ocean winds prevent temperatures from becoming as severe as interior regions of the Barents area tundra. However, it is still relatively cold throughout all months of the year, with summer temperatures rarely exceeding 7–10°C and average winter

Snow / Ice Bare (Arctic tundra / other rocky habitats) Sparse vegetation (alpine tundra / Arctic tundra) Grass / Shrubland (alpine tundra / wetlands) Marshlands (wetlands) Coniferous forest (boreal forest / taiga) Decidous forest (boreal forest / taiga) Cropland

Urban

0 300 km

Figure 2.3 Distribution of forest types and ecozones in the Barents area.

temperatures down to around -30°C. Mean annual precipitation ranges between 150 and 250 mm in mainland areas (Figure 2.2), but is lower in High-Arctic desert areas such as Svalbard and Novaya Zemlya. However, due to low rates of evaporation most tundra areas often appear wet. Permafrost prevents the shallow lakes and bogs from draining and these wetland areas are very important for insects as well as for providing food and water for many birds. In contrast, alpine tundra lacks permafrost and so has better-drained soil.

Tundra vegetation is dominated by perennial dwarf shrubs, sedges, grasses, bryophytes and lichens (Chernov and Matveyeva, 1997; Olson et al. 2001; Kobyakov and Jakovlev, 2013). Freeze-thaw activity, a thin active layer (in areas of permafrost), and soil slippage during the summer thaw contribute to strong controls on vegetation patterns and create a mosaic of microhabitats and plant communities. So even though many of the same plant species (at least for alpine tundra) occur in the taiga, the vegetation cover in the tundra looks different as it is often less continuous and the vascular plant species are shorter.

Animal species have evolved strategies to withstand the harsh environment (CAFF, 2013). Among resident mammals and birds, such as the Arctic hare (Lepus arcticus), Arctic fox (Vulpes lagopus) and ptarmigan (Lagopus muta), morphological adaptations expressed as a thick insulating cover of feathers or fur, and pelage and plumage that turn white in winter and brown in summer are among the adaptive suite of characters common to the terrestrial community.

In addition, physiological adaptations such as the ability to accumulate thick deposits of fat during the short growing season, which then act as insulation and a store of energy for use during winter, are important characteristics of the animals of the northern Barents area. Other common species include lemming (Lemmus spp.) and reindeer (Rangifer tarandus platyrhynchus). For the High Arctic in particular, the resident terrestrial fauna of birds and mammals (Ims et al., 2014) has low species diversity, and this is especially true for Svalbard and Franz Josef Land in the northern reaches of the Barents area. Only the reindeer, Svalbard ptarmigan (Lagopus mutus hyperboreus) and Arctic fox reside on land year round. This is not too surprising given that over 60% of the land in Svalbard and 85% of the land in Franz Josef Land is glaciated. The reindeer in Svalbard is a unique subspecies compared to the mainland or to Greenland; its relationship to animals in Franz Josef Land is not known. The ptarmigan in Svalbard is likely to be the same subspecies as that in Franz Josef Land, based on morphology, so both terrestrial grazers have experienced island-endism phenomena. The Arctic fox travels widely across the sea ice between land masses and so populations are broadly spread and genetically open to other areas. Migratory species such as waterfowl, shorebirds and domesticated reindeer avoid the harsh winter by moving south into the boreal forest or even further south at the end of the growing season. In spring, they return to the tundra to breed and feed.

Many invertebrate species are endemic to the Arctic. Due to their small size and ability to move they can utilize the variety of microhabitats in the landscape, interacting with climatic differences and the contrasting biotic environment (Coulson, 2000). Common groups of invertebrate tundra species

(CAFF, 2013), in terms of species density, include nematodes (Nematoda), springtails (Collembola), non-biting midges (Chironomidae), mosquitoes (Culicidae), flies (Diptera), mites (Arachnida), moths (Lepidoptera), tardigrades (Tardigrada) and small earthworms (Enchytraeidae).

The length of the growing season (seasonal spread of photosynthetic activity) in the Barents area has increased over the past 30 years, and plant flowering has advanced by up to 20 days during a single decade in some areas (Xu et al., 2013).

Primary productivity and vascular plant biomass have increased rapidly in terrestrial communities – particularly in terms of increased growth and expansion of tall shrubs. However, plants in the lowest vegetation layers, such as mosses and lichens, are declining in terms of abundance (CAFF, 2013). See Chapter 6 for further discussion.

2.2.1.3

Glaciers, freshwater ecosystems, wetlands

Glaciers

Glaciers constitute about 4% of the area and are mainly present on Novaya Zemlya and the islands of Svalbard and Franz Josef Land, meaning they are well within the High Arctic as defined by the Arctic Council working group Conservation of Arctic Flora and Fauna (CAFF). Climatic conditions are harsh, with an average July temperature of 4–6°C and an average annual precipitation of less than 200 mm to just above 400 mm. The glaciers are classed into different types based on morphology.

Most dominant by area are the large continuous ice masses – plateau glaciers – that are subdivided into individual ice streams by mountain ridges and nunataks (isolated peaks of rock projecting up through the ice). The presence of small animals during summer has probably been noted by most people walking on glaciers in summer. However, recognizing the existence of glacial ecosystems exploiting habitats such as wet snow, cryoconite holes, streams, ponds and moraines in the ice masses is relatively new (De Smet and van Rompu, 1994; Säwström et al., 2002). According to Hodson et al.

(2008) there are two key glacial ecosystems, one inhabiting the glacier surface (the supraglacial system) and one at the ice-bed interface (the subglacial system). Life in the supraglacial ecosystem, with its snowpack, supraglacial streams and melt pools is characterized by bacteria, algae, phytoflagellates, fungi, viruses and occasional rotifers, tardigrades, and diatoms. The basal ice/till mixtures and subglacial lakes of the subglacial system are dominated by bacteria and probably viruses (Säwström et al., 2007). Despite differences between continental glaciers (decreasing) and oceanic glaciers (increasing), the overall trend is a major decline in glacier volume and area throughout the Barents area. See Chapter 4 for further discussion of changes in glaciers.

Freshwater ecosystems

The Barents area contains abundant and wide-ranging freshwater ecosystems, including lakes, ponds, rivers and streams and a complex array of wetlands and deltas. These contain habitats of varying ecological complexity that support a range of permanent and transitory species adapted to life in a highly variable and extreme environment (Vincent and Laybourn-Parry, 2008). They also serve as important

ecological transition zones within and between terrestrial, freshwater and oceanic ecosystems. Freshwater ecosystems are undergoing rapid change in response to both environmental and anthropogenic drivers. Freshwater is found throughout the Barents area, covering about 5.5% of the area in total and reflecting the entire climatic gradient, with July temperatures ranging from 4°C to 15°C and precipitation of less than 200 mm (i.e. well within the definition of polar desert) to over 1700 mm along parts of the Norwegian coast.

Coastal freshwater fish communities in Norway are dominated by salmon (Salmo salar), and by trout and char (both members of the genus Salvelinus), all of which are cold-water species. High latitude lakes generally have low fish abundance and diversity.

According to Sierszen et al. (2003), Arctic lakes typically have low productivity, supporting small fish populations with slow growth rates, such as Arctic char (Salvelinus alpinus), lake trout (S. namaycush), and lake whitefish (Coregonus clupeaformis), although biomass may be high (Power et al., 2008). Planktonic and benthic communities in Arctic lakes may be very productive (Vincent and Laybourn-Parry, 2008), although this decreases with increasing latitude. The number of species present ranges from 20 to 150 per lake, correlating with latitude, altitude, or water temperature, whereas species composition mainly follows water chemistry (Moore, 1979; Forsström et al., 2009).

According to O’Brien et al. (2004), zooplankton density and biomass can be considerable, mainly limited by food availability and fish predation.

Inland waters show great variety in physical and chemical properties. They include glacier-fed rivers, snow-melt streams, cold oligotrophic lakes, and shallow temporary or permanent ponds. Running freshwaters receive large amounts of glacial meltwater, producing large braided river systems with high sediment loads and fluctuating flow (even no flow after the main snow-melt period) with low temperatures, also in summer. In coastal, glacier-free areas, the streams are snowmelt- and spring-fed and for these as well as for lake outflows (Füreder and Brittain, 2006), conditions can be more favorable for plants and animals, although many snowmelt streams dry up in summer. Temporary thaw ponds, permanent shallow ponds and small lakes are numerous and owing to their shallow depth (usually <2 m) or small catchments, will freeze to the bottom in winter and dry out in summer; both conditions limit permanent residence by biota. Abundant representatives of freshwater invertebrates are springtails (Collembola) and crane flies (Chironomidae) (CAFF, 2013).

The Pechora River is the largest river by volume in the Barents area, with a length of 1809 km and a drainage basin about the size of Finland. This mighty river flows north into the Arctic Ocean on the west side of the Ural Mountains. It lies mostly within the Komi Republic but the northernmost section crosses the Nenets Autonomous Okrug. The Pechora River has the second largest catchment area in the Barents area, exceeded only by the Northern Dvina River. The latter has a drainage basin that includes major parts of the Vologda and the Arkhangelsk Oblasts, as well as areas in the western part of the Komi Republic and the northern part of the Kirov Oblast, and small areas in the north of Yaroslavl and Kostroma Oblasts.

Wetlands

Wetlands occur throughout the Barents area (Figure 2.3) and are an important contributor to the mosaic nature of the landscape. Open wetlands cover 14% of the area, although this percentage increases if tree-covered wetlands are also included.

In this context, wetlands are as defined by the National Wetlands Working Group (1988), as the area in the transition between land, in the conventional sense, and open water. Ecosystems are dominated by the constant presence of excess water. They are also characterized by a water table near the ground surface and so have poorly aerated soil requiring the dominant plants and other organisms to be adapted to wet and anoxic conditions.

Wetlands comprise a mixture of habitats, shaped by past and present management in combination with the physical and biological conditions of each site.

Peatlands are a dominant wetland type within the Barents area; here defined as areas where the peat is at least 30 cm deep and often up to 40 cm deep (Joosten and Clarke, 2002).

Plants, bacteria, and more than 500 species of fungi, liverwort, lichen and algae occur in peatlands. The most important groups, represented by several hundred species are the green algae (including desmids) and diatoms (for reviews see Hingley, 1993; Gilbert and Mitchell, 2006). Factors such as water chemistry, continuously open water and gradients

Plants, bacteria, and more than 500 species of fungi, liverwort, lichen and algae occur in peatlands. The most important groups, represented by several hundred species are the green algae (including desmids) and diatoms (for reviews see Hingley, 1993; Gilbert and Mitchell, 2006). Factors such as water chemistry, continuously open water and gradients

Im Dokument Impact analysis and consequences of change (Seite 22-28)