This volume presents the results of an extensive, long-running program of research on mountain birch, Betula pubescens ssp. czerepanovii, conducted by the Nordic Subarctic and Subalpine Ecology (NSSE) group, as part of the UNESCO/MAB Northern Sciences Network. The book contains an almost complete overview of NSSE research and results, presented in 31 data-rich chapters in six sections: introduction, ecosystem distribution, plant growth, animal herbivory, impact by man, and conclusions. These chapters cover the history, climatic influences and interactions of animals and insects on the growth and distribution of mountain birch, considering both physical and chemical aspects of performance and distribution, and using research methods ranging from plant and animal ecophysiology to social anthropology and remote sensing. The work also examines past and future climates and the effects of air pollution on the growth and distribution of mountain birch and associated herbs, insect, rodent and bird populations. This information is especially important in view the effects of climate change, topography and grazing on the treeline. Both wild and domestic animal populations, including domestic and semi-domestic reindeer, are responsible for grazing and trampling of birch forest. Reindeer herding and migration have been prevented or limited during the last century for political and economic reasons, while farming and increased tourism have also had direct impacts on birch forest regeneration through trampling and new building projects. Mountain birch are also used as firewood, for lumber or furniture, and traditionally by the Sami (Lappish) people for tools and handicrafts. The book includes bibliographic references and index.