The PPS Arctic Norway project is the Norwegian contribution to the circumpolar IPY core project PPS Arctic (Present day processes, Past changes, and Spatiotemporal variability of biotic, abiotic and socio-environmental conditions and resource components along and across the Arctic delimitation zone) coordinated by Dr. A. Hofgaard, NINA, and Dr. G. Rees, Scott Polar Res. Inst., UK. PPS Arctic is a ... multidisciplinary research cluster focusing on the southern border of the Arctic with its transition zone into shrub and tree dominated regions. This zone is internationally recognised due to its exceptional importance in terms of climate feedbacks, global vegetation, and settlements by indigenous people. Large scale changes in the structure and position of this zone (as predicted) will affect the total arctic environment and the global climate. The Norwegian contribution, PPS Arctic Norway, does not cover the entire scientific width of the core project but has principal responsibilities within two main scientific domains of the core project: i) vegetation structure and present tree regeneration capacity, and spatiotemporal dynamics of the tundra-taiga transition zone in the southern Arctic; and ii) definition and spatiotemporal characterisation of the zone. Study regions in focus are northern Norway and north-western Russia with reference regions in western and eastern Canada. The project has a strong international profile including close cooperation with Russian institutions. The scientific merits will be both a snapshot for IPY, of the status of the southern Arctic climate-environmental boundary, and this information placed in a broader time frame. Both which are essential for policy makers and managers when assessing regional to global consequences of environmental change in the Arctic.