Holocene fire in Fennoscandia and Denmark Jennifer L. Clear A,C,D , Chiara Molinari B and Richard H. W. Bradshaw C A Department of Forest Ecology, Czech University of Life Sciences, Kamy ´cka 129, CZ-16521 Prague, Czech Republic. B Department of Physical Geography and Ecosystem Science, Lund University, S-22362 Lund, Sweden. C Present address: Department of Geography and Planning, University of Liverpool, Chatham Street, Liverpool, L69 7ZT, UK. D Corresponding author. Email: clear@fld.czu.cz Abstract. Natural disturbance dynamics, such as fire, have a fundamental control on forest composition and structure. Knowledge of fire history and the dominant drivers of fire are becoming increasingly important for conservation and management practice. Temporal and spatial variability in biomass burning is examined here using 170 charcoal and 15 fire scar records collated throughout Fennoscandia and Denmark. The changing fire regime is discussed in relation to local biogeographical controls, regional climatic change, anthropogenic land use and fire suppression. The region has experienced episodic variability in the dominant drivers of biomass burning throughout the Holocene, creating a frequently changing fire regime. Early Holocene biomass burning appears to be driven by fuel availability. Increased continentality during the mid-Holocene Thermal Maximum coincides with an increase in fire. The mid–late Holocene front-like spread of Picea abies (Norway spruce) and cooler, wetter climatic conditions reduce local biomass burning before the onset of intensified anthropogenic land use, and the late Holocene increase in anthropogenic activity created artificially high records of biomass burning that overshadowed the natural fire signal. An economic shift from extensive subsistence land use to agriculture and forestry as well as active fire suppression has reduced regional biomass burning. However, it is proposed that without anthropogenic fire suppression, the underlying natural fire signal would remain low because of the now widespread dominance of P. abies. Additional keywords: biomass burning, climate change, fire suppression, slash and burn. Received 8 November 2013, accepted 21 March 2014, published online 29 July 2014 Introduction Heavily managed forests and active fire suppression have created an ecosystem almost free of fire throughout Fennos- candia and Denmark (Zackrisson 1977; Wallenius 2011). The absence of fire from the landscape not only affects natural forest regeneration (Ruokolainen and Salo 2006) but also reduces floral and faunal biodiversity and threatens the sur- vival of red-listed species such as saproxylic beetles that are reliant on the regular occurrence of forest fire (Lindbladh et al. 2003). This absence of fire from the Fennoscandian Boreal ecosystem is thought to have contributed to the widespread dominance of Picea abies and subsequent decline in deciduous species (Bjune et al. 2009) with P. abies becoming the most abundant tree species in northern European forests and emerging as a new boreal forest keystone species (Seppa ¨ et al. 2009). Fire has not always been so rare throughout Fennos- candia and Denmark: fire scars record a significantly more intensive fire regime in the recent past (e.g. Niklasson and Granstro ¨m 2000; Power et al. 2013; Storaunet et al. 2013). Fire scars are valuable for understanding past human fire activity (Neolithic to present day slash and burn activity). However, fire scar records rarely exceed 600 years of age in Fennoscandia (Wallenius et al. 2007) and do not pre-date the time of significant anthropogenic influence. The anthropogenic fire signal recorded in fire scars gives an artificially high perception of the historical fire frequency regime that dilutes the natural fire frequency signal in Fennos- candia and Denmark. By contrast, charcoal series record fire history on a palaeoecological timescale, which is far beyond the temporal capability of fire scars and pre-dates significant anthropogenic disturbance (Clear et al. 2013), with macro- scopic charcoal recording local fires with high spatial precision (Ohlson and Tryterud 2000; Higuera et al. 2007). It is only because of palaeoecological data on biomass burning that we can understand the influence of natural drivers of fire. Even with minimal anthropogenic disturbance it remains difficult to disentangle the complex interactions of natural drivers of biomass burning: climate variability, vegetation type and fuel availability (Molinari et al. 2013). The aim of this paper is to combine available charcoal and fire scar records from Fennoscandia and Denmark to explore spatial and temporal heterogeneity and variability in biomass burning. We aim to identify the changing dominant drivers and controls of fire throughout the early, mid- and late Holocene. CSIRO PUBLISHING International Journal of Wildland Fire 2014, 23, 781–789 http://dx.doi.org/10.1071/WF13188 Journal compilation Ó IAWF 2014 Open Access www.publish.csiro.au/journals/ijwf