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.

Aims: An Arctic Vegetation Classification (AVC) is needed to address issues related to rapid Arctic-wide changes to climate, land-use, and biodiversity. Location: The 7.1 million km 2 Arctic tundra biome. Approach and conclusions: The purpose, scope and conceptual framework for an Arctic Vegetation Archive (AVA) and Classification (AVC) were developed during numerous workshops starting in 1992. The AVA and AVC are modeled after the European vegetation archive (EVA) and classification (EVC). The AVA will use Turboveg for data management. The EVC will use a Braun-Blanquet (Br.-Bl.) classification approach. There are approximately 31,000 Arctic plots that could be included in the AVA. An Alaska AVA (AVA-AK, 24 datasets, 3026 plots) is a prototype for archives in other parts of the Arctic. The plan is to eventually merge data from other regions of the Arctic into a single Turboveg v3 database. We present the pros and cons of using the Br.-Bl. classification approach compared to the EcoVeg (US) and Biogeoclimatic Ecological Classification (Canada) approaches. The main advantages are that the Br.-Bl. approach already has been widely used in all regions of the Arctic, and many described, well-accepted vegetation classes have a pan-Arctic distribution. A crosswalk comparison of Dryas octopetala communities described according to the EcoVeg and the Braun-Blanquet approaches indicates that the non-parallel hierarchies of the two approaches make crosswalks difficult above the plantcommunity level. A preliminary Arctic prodromus contains a list of typical Arctic habitat types with associated described syntaxa from Europe, Greenland, western North America, and Alaska. Numerical clustering methods are used to provide an overview of the variability of habitat types across the range of datasets and to determine their relationship to previously described Braun-Blanquet syntaxa. We emphasize the need for continued maintenance of the Pan-Arctic Species List, and additional plot data to fully sample the variability across bioclimatic subzones, phytogeographic regions, and habitats in the Arctic. This will require standardized methods of plot-data collection, inclusion of physiogonomic information in the numeric analysis approaches to create formal definitions for vegetation units, and new methods of data sharing between the AVA and national vegetation-plot databases.

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