Do shifting forest limits in south-west Norway keep up with climate change?

Abstract

In this paper, high-resolution remote sensing data were used to investigate whether a change in the alpine forest limit is observable on the Hardangervidda plateau in south-west Norway. A comparison of declassified CORONA images from 1965 with modern digital aerial surveys from 2004 provided evidence for a change of forest limits towards higher elevations. However, the observed upslope movement is lower than should be expected considering local climate warming and changes in land use. Projections of climate-induced impacts on the forest limits on Hardangervidda based on equilibrium assumptions do not hold true. There are considerable differences between the reaction of forest cover and changes in tree line. Forest cover in alpine areas might show an extensive time lag in the reaction to climatic change, even though conditions for growth of individual trees may have improved considerably. Consequentially, it should be expected that warming temperatures will not cause an immediate and homogenous advancement of forest cover towards higher elevations.

Keywords:

• Climate change
• CORONA images
• forest dynamics
• Hardangervidda
• remote sensing
• Scandes
• timberline

Acknowledgements

I am thankful to the German Academic Exchange Service and the European Community for the funding that was essential for this study. Special thanks are due to Knut Krzywinski and the Ecological and Environmental Change Research Group at the University of Bergen for providing exceptional suitable research environment and to Leif Kastdalen and Einar Lieng from Hedmark University College for providing crucial data and valuable help.