D. Thannheiser

Vegetation Changes in the Nordic Mountain Birch Forest: the Influence of Grazing and Climate Change

Abstract The study focuses on vegetation changes in the Nordic mountain birch forest in northern Norway, covering a period of more than 40 yr. The study area comprises the municipalities of Kautokeino and Karasjok on Finnmarkskvidda; it is predominantly covered by lichen and dwarf shrub vegetation. Sizes of various vegetation classes were estimated by the use of remote-sensing techniques and ground surveys. A significant change in vegetation cover during the study period was registered in the whole study area. Vegetation types dominated by bilberry (Vaccinium myrtillus), wavy hair-grass (Deschampsia fleuxuosa), the dwarf cornel (Cornus suecica), and mosses have tripled in abundance compared to 40 yr ago. In contrast, lichen-dominated heaths and woodland (forests), preferred by the reindeer stocks intensively utilizing these areas of Finnmarksvidda, have decreased by approximately 80% in abundance during the same period. Correspondingly, there has been a significant increase in the extent of birch forests especially in Kautokeino (90% increase). The reason for the steep decline in lichen-dominated areas appears to be a direct consequence of the intensive grazing by the increasing reindeer population in the period 1961–1987, but climate change (increased precipitation), caterpillar attacks, and long-transported air pollution (e.g., nitrogen) may also have accentuated the increase of forests and other vegetation types.

CO2‐fluxes in different plant communities of a high‐Arctic tundra watershed (Western Spitsbergen)

There is little information on (1) whether the net carbon balance is positive or negative in different habitats in high Arctic ecosystems such as Spitsbergen today, and (2) what effect a cloudier, cooler summer could have on carbon balance. To provide data on this subject CO2-flux measure- ments in different plant communities were made in the high- Arctic coastal tundra of Spitsbergen, using a mobile macro- cuvette system based on infrared gas analysis. The study area was situated on the exposed west coast, where westerly winds produce precipitation daily in the form of rain, drizzle and fog. During the cold and cloudy measurement period in 1996, light and surface temperatures were limiting for primary producers, resulting in low size and low physiological activity of the plants. Net CO2-flux measurements showed carbon fluxes from soil to atmosphere in most of the communities even during the brightest hours of the day, when mean photon flux density was 325 mmol m-2 s-1. Calculations based on spatial distribution of the plant communities and soils in the water- shed combined with C-flux measurements revealed informa- tion on daily carbon loss. For instance, the Drepanocladus community, covering 21 % of the catchment area, was respon- sible for 42.6 % of the catchment carbon loss. Only two of nine investigated plant communities, the Racomitrium and a Salix- Saxifraga community on debris, both adapted to frequent fog situations, were able to compensate for respiratory CO2-losses under the prevailing low light conditions during daytime. Since there were no significant sunny periods in this area in the summer of 1996, the habitats of the investigated coastal tundra finished the season with a marked carbon loss due to increased cloudiness.

The Vegetation Changes and Recent Impact on the Mountain Birch Forest During the Last 40 Years

The study described in this chapter focuses on vegetational changes in the mountain birch forest on the Finnmarksvidda, in the area of Maze and in the region of the Malselv valley in the county of Troms (northern Norway). The study covered a period of 37 years between 1964 and 2001. The area around the riverine settlement of Maze is predominantly covered by mountain birch, while at higher elevation and on the mountain tops, mainly treeless-fell lichen heath occurs interspersed with small islands of birch forest. A vegetational shift in the mountain birch forest plant communities is particularly noticeable in the vegetational ground layer, which includes herbs, mosses and lichens. The studies concentrated primarily on the dry birch forest type, because a floral change was not noticeable in the wetter birch forests (meadow or bog forests). Unfortunately, only a few plant sociological releves were conducted during 1964 and 1965. After 37 years the exact sites of these releves were revisited and considerable differences were noticed in species presence and abundance. However, this study was carried out only for the core area of Finnmarksvidda and is not decisive for the wet forest plant communities (Rubo chamaemorei–Betuletum and Geranio–Betuletum; see Chap. 3). During the last 30–40 years, the anthropogenic development of the Finnmarksvidda with road building, growth of small settlements and construction of cabin complexes has resulted in increased pressure on the mountain birch forest (cf. Chaps. 15 and 24). The birch forest was cut in places to make way for buildings and roads, but the most severe damage to the birch forest was from harvesting firewood as well as a great increase in reindeer grazing. Additionally, the effects of climatic change play an important role (see Chap. 1).

Economic Limits and Possibilities for Sustainable Utilization of Northern Birch Forests

The birch ecosystems have been vital for human survival in northern Europe since the first humans entered these areas, and the ecosystems have over time been rather strongly exposed to multiple use through human occupancy as well as other related activities. The main purpose of the HIBECO (Human Interactions with the mountain Birch ECOsystem) project has been to provide greater knowledge of the human impacts on the northern birch forest ecosystems and natural conditions, and the future sustainability of these ecosystems (see Preface). As such, economic issues will have to play an important role, and the main objective of this chapter is to analyse the economic possibilities and limits for sustainable utilization of these ecosystems. This is done by, first, focusing on some theoretical issues which are essential prerequisites to clarify in such types of analyses, and, second, providing empirical results from the study areas included in the project. The concept of “economic limits” in this chapter is related to two principal factors: supply (i.e. limits related to the supply of services and goods from the birch ecosystems considered) and demand (i.e. limits to the demand of goods and services these ecosystems provide).

Soils and Nutrients in Northern Mountain Birch Forests: A Case Study from Finnmarksvidda, Northern Norway

Although birch forests cover large areas of northern Fennoscandia, with the mountain birch Betula pubescens ssp. czerepanovii often forming the altitudinal and arctic forest line, very little is known about the soils typical for these areas. This is a great difference from the boreal coniferous region farther to the south and the arctic–alpine belt of the Caledonian mountain range, where quite a few studies dealing with soils in different ways have been carried out in the past decades (e.g. Jauhiainen 1969, 1970; Ellis 1979, 1980, 1983, 1985; Kuhn 1983; Breburda 1987; Meyer et al. 1988; Venzke 1990; Darmody et al. 2000). There are only a few publications on Quaternary deposits and soils in the northern Fennoscandian mountain birch forests (e.g. Haapasaari 1988; Stutzer 1995), the most comprehensive describing soil types and their distribution near the forest line some kilometres to the south of Alta, Finnmark (Mosimann 1981). More recent publications concentrate on special aspects of soil formation within the birch forests, such as the influence of long-lasting frozen ground and permafrost (e.g. Meier 1985, 1987, 1991, 1996). With this background, soils were investigated in more detail during the summers of 2001 and 2002 as a case study in connection with the EU project HIBECO (Human Impact on Mountain Birch Ecosystems) in the gently undulating plateau landscape of the Finnmarksvidda between the Alta river power plant in the north and the Finnish-Norwegian national border in the south (see details given on the attached CD, and Chap. 2).

The Nordic Mountain Birch Ecosystem - Challenges to Sustainable Management

From a global perspective, the Nordic mountain birch ecosystem is a unique feature of northwestern Europe (see Chap. 1). Although it may appear rather homogeneous and simple, a closer look reveals striking regional and local variation in numerous characteristics such as geology, soils, climate, plant productivity, species composition and herbivory, as well as in the history and human activities in this area. These differences have been pointed out repeatedly throughout this volume. The variability not only poses a great resource, but also a great challenge to sustainable management of the mountain birch (and adjacent alpine/tundra) ecosystems. From the variability of many characteristics, it is obvious that the critical or problematic issues vary regionally. Consequently, sustainable management principles are likely to differ from area to area. The specific structure and properties of the mountain birch forest allow a subdivision into different vegetational units that are characterized by particular ecological conditions (see Chap. 3), and the human impact on the various forest types can be considerable. The density of birch forests and the position of forest lines have varied over time (see Chap. 1) owing to variations in climate and in the human exploitation of birch forests, including domestic herbivores. Particularly in recent times, other human activities, such as tourism and pollution, have had impacts on this ecosystem. Another important, natural cause for long-term dynamics in forest density and productivity is the outbreak of major insect herbivores (mainly the autumnal moth, see Chaps. 5, 9, 12). Events where the stems are killed and the forest is rejuvenated, or the forest is killed, have a major impact on all aspects of the forest’s biology and socio-economic utilization for many decades. There is thus a potential conflict between the longterm dynamics of the mountain birch forest caused by the natural insect herbivores and human utilization of these ecosystems. The effects from severe

Changes of Plant Community Patterns, Phytomass and Carbon Balance in a High Arctic Tundra Ecosystem Under a Climate of Increasing Cloudiness

Climate models predict a pronounced warming in the Arctic which will be accompanied by an increasing cloudiness during the vegetation period in summer. This study determines which consequences can be expected regarding the spreading of plant communities, their phytomass and the spatial carbon balance in a high arctic catchment under a climate with increased cloudiness after 40–50 years. Using the present and the most likely future distribution patterns of the prevailing plant communities, changes in phytomass and CO2 fluxes were calculated. The calculations showed that an alteration in the distribution of the plant communities is much less effective in changing the carbon balance of the high arctic tundra than a change of important prevailing ecological conditions, such as light or length of the snow-free period.

Competition Over Nature, Space, Resources and Management in the Mountain Birch Forest Ecosystem in Northernmost Fennoscandia: A Synthesis

Since deglaciation,human populations have lived in and used resources in arctic and subarctic terrestrial ecosystems. Especially the mountain birch (Betula pubescens ssp. czerepanovii) forest ecosystem of northernmost Fennoscandia and coastal areas of the European North Atlantic arch has seen a variety of human adaptations to this physical environment over the last few millennia. Local populations in the North Atlantic rimland – from east to west,the aboriginal Sami, immigrant Finnish,Scandinavian,Celtic (Scotland) settlers,and to a lesser degree Icelanders and Inuit (Kalaallit Nunaat/Greenland) – along with herded and domestic animals, such as reindeer and sheep, have utilized these northern forest environments, intensively competing over specific resources through hunting, fishing, gathering, reindeer herding, hay–dairy agriculture, forestry, material production and, finally, modern industrial activities including tourism and recreation. Moreover, nature at the timberline, the forests and in particular those dominated by birch, also holds intrinsic cultural and spiritual values that are inherent elements of northern peoples’ quality of life (see Chap.18). It is this varied human interest and its impact on the mountain birch forests that are the focus of the studies in this section. There exists an intricate relationship between humans and mountain birch forests expressed by detailed environmental knowledge based on the historic and current use of birch by both local residents and external users (see Chaps. 16 and 18). In the early 21st century, the socio-economic relationships with these forest resources and the cultural values given to them are changing rapidly, locally and globally, within the context of increased competition over space and resources, expanding modernization, political and economic globalization (see Chaps. 19, 23, 24) and environmental conditions (see Chap. 17). Thus, for example, the recent northern extension of the European Union with its administrative and political apparatus is just one example of impact on