A high-resolution GIS null model of potential forest expansion following land use changes in Norway

Abstract

During recent decades, forests have expanded into new areas throughout the whole of Norway. The processes explained as causing the forest expansion have focused mainly on climate or land use changes. To enable a spatially explicit separation of the effects following these two main drivers behind forest expansion, the authors set out to model the potential for natural forest regeneration following land use abandonment, given the present climatic conditions. The present forest distribution, a number of high-resolution land cover maps, and GIS methods were used to model the potential for natural forest regeneration. Furthermore, the results were tested with independent local models, explanatory variables and predictive modelling. The modelling results show that land use abandonment, in a long-term perspective, has the climatic and edaphic potential to cause natural forest regeneration of 48,800 km², or 15.9% of mainland Norway. The future natural forest regeneration following land use change or abandonment can now be spatially separated from the effects of climate changes. The different independent model tests support the main findings, but small fractions of the modelled potential natural forest regeneration will probably be caused by other processes than land use abandonment.

Keywords:

• Climatic forest line
• land use
• model testing
• natural forest regeneration
• potential forest
• predictive modelling
• semi-natural landscape

Acknowledgements

Børre Aas, Vegar Bakkestuen, Esgo Kuiper, Catriona Turner and the reviewers gave valuable comments, technical assistance or helped to improve the language. All are gratefully acknowledged. This article has been supported by the Norwegian Research Council (Project Number 189977).