University of Oulu

Aakala, T., Pasanen, L., Helama, S., Vakkari, V., Drobyshev, I., Seppä, H., Kuuluvainen, T., Stivrins, N., Wallenius, T., Vasander, H. and Holmström, L. (2018), Multiscale variation in drought controlled historical forest fire activity in the boreal forests of eastern Fennoscandia. Ecol Monogr, 88: 74–91. doi:10.1002/ecm.1276

Multiscale variation in drought controlled historical forest fire activity in the boreal forests of eastern Fennoscandia

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Author: Aakala, Tuomas1; Pasanen, Leena2; Helama, Samuli3;
Organizations: 1Department of Forest Sciences, University of Helsinki
2Department of Mathematical Sciences, University of Oulu
3Natural Resources Institute Finland (LUKE)
4Finnish Meteorological Institute
5Sveriges lantbruksuniversitet (SLU)
6Institut de recherche sur les forêts, Université du Québec en Abitibi-Témiscamingue (UQAT)
7Department of Geosciences and Geography, University of Helsinki
8Department of Geography, Faculty of Geography and Earth Sciences, University of Latvia
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: John Wiley & Sons, 2018
Publish Date: 2018-02-13


Forest fires are a key disturbance in boreal forests, and characteristics of fire regimes are among the most important factors explaining the variation in forest structure and species composition. The occurrence of fire is connected with climate, but earlier, mostly local-scale studies in the northern European boreal forests have provided little insight into fire–climate relationship before the modern fire suppression period. Here, we compiled annually resolved fire history, temperature, and precipitation reconstructions from eastern Fennoscandia from the mid-16th century to the end of the 19th century, a period of strong human influence on fires. We used synchrony of fires over the network of 25 fire history reconstructions as a measure of climatic forcing on fires. We examined the relationship between fire occurrence and climate (summer temperature, precipitation, and a drought index summarizing the influence of variability in temperature and precipitation) across temporal scales, using a scale space multiresolution correlation approach and Bayesian inference that accounts for the annually varying uncertainties in climate reconstructions. At the annual scale, fires were synchronized during summers with low precipitation, and most clearly during drought summers. A scale-derivative analysis revealed that fire synchrony and climate varied at similar, roughly decadal scales. Climatic variables and fire synchrony showed varying correlation strength and credibility, depending on the climate variable and the time period. In particular, precipitation emerged as a credible determinant of fire synchrony also at these time scales, despite the large uncertainties in precipitation reconstruction. The findings explain why fire occurrence can be high during cold periods (such as from the mid-17th to early-18th century), and stresses the notion that future fire frequency will likely depend to a greater extent on changes in precipitation than temperature alone. We showed, for the first time, the importance of climate as a decadal-scale driver of forest fires in the European boreal forests, discernible even during a period of strong human influence on fire occurrence. The fire regime responded both to anomalously dry summers, but also to decadal-scale climate changes, demonstrating how climatic variability has shaped the disturbance regimes in the northern European boreal forests over various time scales.

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Series: Ecological monographs
ISSN: 0012-9615
ISSN-E: 1557-7015
ISSN-L: 0012-9615
Volume: 88
Issue: 1
Pages: 74 - 91
DOI: 10.1002/ecm.1276
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: This work was supported by the Academy of Finland (projects. no 276255, 252629, and 275969, and project. no 288267 for S. Helama). V. Vakkari is beneficiary of an AXA Research Fund postdoctoral grant. I. Drobyshev was supported by EU consortium PREREAL, Formas grant 239-2014-1866, and NSERC grant (DDG-2015-00026).
Academy of Finland Grant Number: 276255
Detailed Information: 276255 (Academy of Finland Funding decision)
252629 (Academy of Finland Funding decision)
275969 (Academy of Finland Funding decision)
288267 (Academy of Finland Funding decision)
Copyright information: © 2017 by the Ecological Society of America. Published in this repository with the kind permission of the publisher.