Strong anthropogenic signals in historic forest fire regime: a detailed spatiotemporal case study from south-central Norway

• Published in: Canadian Journal of Forest Research
• Main Authors: Storaunet, Ken Olaf, Rolstad, Jørund, Toeneiet, Målfrid, Blanck, Ylva-li
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2013
• Subjects: Norway; Fennoscandian
• Online Access: http://dx.doi.org/10.1139/cjfr-2012-0462; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjfr-2012-0462; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjfr-2012-0462

To better understand the historic range of variability in the fire regime of Fennoscandian boreal forests we cross-dated 736 fire scars of remnant Scots pine (Pinus sylvestris L.) wood samples in a 3.6 km 2 section of the Trillemarka-Rollagsfjell Reserve of south-central Norway. Using a kernel range application in GIS we spatially delineated 57 individual forest fires between 1350 and the present. We found a strong anthropogenic signal in the fire regime from 1600 and onwards: (i) infrequent variably sized fires prior to 1600 shifted to frequent fires gradually decreasing in size during the 1600s and 1700s, with only a few small fires after 1800; (ii) time intervals between fires and the hazard of burning showed substantial differences pre- and post-1600; (iii) fire seasonality changed from late- to early-season fires from the 1626 fire and onwards; and (iv) fire severity decreased gradually over time. Written sources corroborated our results, narrating a history where anthropogenic forest fires and slash-and-burn cultivation expanded with the increasing population from the late 1500s. Concurrently, timber resources increased in value, gradually forcing slash-and-burn cultivators to abandon fires on forest land. Our results strengthen and expand previous Fennoscandian findings on the anthropogenic influence of historic fire regimes.