F. E. Wielgolaski

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.

Phenology and Performance of Mountain Birch Provenances in Transplant Gardens: Latitudinal, Altitudinal and Oceanity-Continentality Gradients

Phenology is the study of timing of annually recurring events in plants, especially in relation to year-to-year variation in environmental factors. In forestry, it has been known for many years that transplantation of coniferous tree provenances between southern and northern latitudes has a considerable impact on both phenology and productivity of the trees (Hagem 1931; Kalela 1938; Heikinheimo 1949; Magnesen 1992; Beuker 1994). It has, for instance, been observed that bud break and flowering occur earliest in trees of the northernmost origin when grown under uniform conditions in a transplant garden (Reader 1982; Beuker 1994). They also end growth earliest in autumn (Morgenstern 1996). Generally, the photoperiod has been found to be the dominant factor in determining the cessation of growth in northern plants (Partanen and Beuker 1999). The long-continuing growth of southern provenances planted further north has often caused a weak hardening of the shoots by the end of the summer, which has resulted in frost damage during winter and spring. Transplantation experiments are often used in determining the degree of ecotypic differentiation among different provenances of a tree species. In a transplantation experiment, seedlings or micropropagated saplings of different provenances are transferred to given environmental conditions and their responses are then determined. When the provenances are grown under uniform conditions for comparative ecophysiological research, all the observed phenotypic differences among the provenances are due to differences in their genotypes – provided that the transplants of different provenances have been treated in the same way before and during transplantation. These different responses may be used to estimate the degree of ecotypic differentiation within a tree species. On the other hand, when the same provenance or geno-

Rates and processes of natural regeneration in disturbed habitats.

Surface disturbance from recreational hiking and camping has been reported from a number of ecosystems in various parts of the world, and is also common in the Nordic mountain birch ecosystem. This will be of increasing importance in the future as the use of these birch forests and adjacent alpinearctic areas for tourism purposes has grown dramatically in recent decades (Back et al. 1989; Ilyina and Mieczkowski 1992; Sippola et al. 1995; Gnieser 2000; Godde et al. 2000; Prokosch 2001; Monz 2002; Chaps. 15 and 24). Recovery after surface disturbances in high altitude and latitude mountain birch systems is normally slow due to the generally low temperatures, short growing seasons, and the often nutrient-poor soil (see below). In dense mountain birch forests also low light intensity may reduce the recovery rate. Very few controlled field experiments have been carried out on the ecological effect of surface disturbance within the northern mountain birch forest itself. However, it may be postulated that the effects will be of the same order as in similar vegetation types above and north of the present tree line. The Nordic mountain birch forest is also expected to expand in response to climate change to higher elevation and further north, as stressed in several chapters in this volume (see, e.g., Chaps. 1 and 21). This means that the plant field and bottom layers of today’s low alpine-arctic ecosystems in the future may be within the subalpine–subarctic mountain birch forests in Fennoscandia. Ecological impacts of surface disturbance, natural or man-made, are many and include, among others, reductions in the diversity and abundance of plant species (Liddle 1997), growth forms (Bayfield et al. 1981; Forbes 1992b) and soil fauna (Bayfield 1979a; Kevan et al. 1995), changes in vegetation cover, structure and productivity (Cole and Bayfield 1993; Forbes et al. 2001), floristic convergence among sites and colonization by non-native species (Schreiner 1982; Gorchakovskii 1985; Gorchakovskii and Korobeinikova

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

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