Burning boreal forests: how did fire regimes in Fennoscandia change during the Holocene and why?

Abstract

Wildfire is an important natural phenomenon that affects Fennoscandian boreal forest ecosystems and their functioning. Due to the increase in large boreal wildfires and the damage they cause, knowledge on the natural fire regime is needed to manage these fires. This knowledge can be gained through the reconstruction of fire histories with methods such as palaeoecological studies of past ecosystems, which are able to look back to the period when humans had little impact on the landscape. This review aims to summarise knowledge on wildfires in Fennoscandian boreal forests throughout the Holocene and their drivers. This is done in order to discuss how the study of historical wildfires may be relevant for the management of future wildfires, and where the main challenges lie. Different methods for the reconstruction of fire regimes have their own strengths and weaknesses, and depending on the objectives of a study, the most suitable approach should be chosen. Wildfire regimes in Fennoscandia changed throughout the Holocene and were mostly driven by climate, vegetation and different forms of human activity. However, connecting drivers to fire regimes remains a large challenge, due to the interactions between the different drivers and varying local conditions and variables between study sites. Moreover, there still exist uncertainties about climate in Fennoscandia during the Holocene. Multi-proxy approaches may be a valuable addition to the toolbox of fire history reconstruction, as they can provide a more complete picture of past ecosystems, climates and fire histories. The outcomes of palaeoecological research can then be applied to appropriate management for boreal forests and wildfires in those ecosystems.