Aim To reconstruct spatial and temporal patterns of European fire activity during the Holocene and to explore their potential drivers, by relating biomass burning to simulated biotic and abiotic parameters. Location Europe.Methods Holocene fire activity was investigated based on 156 sedimentary charcoal records from lakes and peat bogs across Europe. Charcoal data covering the last 9000 years were statistically compared with palaeoclimate data derived from the Max Planck Institute for Meteorology/University of Wisconsin-Madison Earth System Model, with vegetation and fire indices simulated with the dynamic vegetation model lpj-guess and with two independent scenarios of past anthropogenic land-cover change. ResultsThe combined sedimentary charcoal records suggest that there was little fire activity during the early and the middle Holocene compared with recent millennia. A progressive increase in fire frequency began around 3500 cal. yr bp and continues into the late Holocene. Biomass burning rose sharply from 250 cal. yr bp onwards, reaching a maximum during the early Industrial Era and then declining abruptly. When considering the whole Holocene, the long-term control of fire is best explained by anthropogenic land-cover change, litter availability and temperature-related parameters.Main conclusions While the general patterns found across Europe suggest the primary role of vegetation, precipitation and temperature-related parameters in explaining fire dynamics during the early Holocene, the increase in fire activity observed in the mid-late Holocene is mainly related to anthropogenic land-cover changes, followed by vegetation and temperature-related parameters. The 20thcentury decline in biomass burning seems to be due to increased landscape fragmentation and active fire suppression policies. Our hypothesis that human activities played a primary role in Holocene biomass burning across Europe could be tested by improved palaeoclimate reconstructions and more refined representations of anthropogenic fires in climate and vegetation models.

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.

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The influence of different drivers on changes in North American and European boreal forests biomass burning (BB) during the Holocene was investigated based on the following hypotheses: land use was important only in the southernmost regions, while elsewhere climate was the main driver modulated by changes in fuel type. BB was reconstructed by means of 88 sedimentary charcoal records divided into six different site clusters. A statistical approach was used to explore the relative contribution of (a) pollen-based mean July/summer temperature and mean annual precipitation reconstructions, (b) an independent model-based scenario of past land use (LU), and (c) pollen-based reconstructions of plant functional types (PFTs) on BB. Our hypotheses were tested with: (a) a west-east northern boreal sector with changing climatic conditions and a homogeneous vegetation, and (b) a north-south European boreal sector characterized by gradual variation in both climate and vegetation composition. The processes driving BB in boreal forests varied from one region to another during the Holocene. However, general trends in boreal biomass burning were primarily controlled by changes in climate (mean annual precipitation in Alaska, northern Quebec, and northern Fennoscandia, and mean July/summer temperature in central Canada and central Fennoscandia) and, secondarily, by fuel composition (BB positively correlated with the presence of boreal needleleaf evergreen trees in Alaska and in central and southern Fennoscandia). Land use played only a marginal role. A modification towards less flammable tree species (by promoting deciduous stands over fire-prone conifers) could contribute to reduce circumboreal wildfire risk in future warmer periods.

Questions We investigated the changing role of climate, forest fires and human population size in the broad‐scale compositional changes in Holocene vegetation dynamics before and after the onset of farming in Sweden (at 6,000 cal yr BP) and in Finland (at 4,000 cal yr BP). Location Southern and central Sweden, SW and SE Finland. Methods Holocene regional plant abundances were reconstructed using the REVEALS model on selected fossil pollen records from lakes. The relative importance of climate, fires and human population size on changes in vegetation composition was assessed using variation partitioning. Past climate variable was derived from the LOVECLIM climate model. Fire variable was reconstructed from sedimentary charcoal records. Estimated trend in human population size was based on the temporal distribution of archaeological radiocarbon dates. Results Climate explains the highest proportion of variation in vegetation composition during the whole study period in Sweden (10,000–4,000 cal yr BP) and in Finland (10,000–1,000 cal yr BP), and during the pre‐agricultural period. In general, fires explain a relatively low proportion of variation. Human population size has significant effect on vegetation dynamics after the onset of farming and explains the highest variation in vegetation in S Sweden and SW Finland. Conclusions Mesolithic hunter‐gatherer populations did not significantly affect vegetation composition in Fennoscandia, and climate was the main driver of changes at that time. Agricultural communities, however, had greater effect on vegetation dynamics, and the role of human population size became a more important factor during the late Holocene. Our results demonstrate that climate can be considered the main driver of long‐term vegetation dynamics in Fennoscandia. However, in some regions the influence of human population size on Holocene vegetation changes exceeded that of climate and has a longevity dating to the early Neolithic.

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Data from four soil profiles studied through pollen and macroscopic charcoal analyses were used to identify specific palynological assemblages associated with atraditional land-use system documented in the Eastern Ligurian Apennines (NW Italy) between the 18th and early 20th century, concerning a cyclical use of grey alder plots for temporary cultivations involving to the use of controlled fire. This is the first attempt to verify on palynological evidence some hypotheses raised by previous historical ecology studies about the consequences of this agricultural practice (recently named alnocoltura) on past and present vegetation. Our investigations underline (1) high percentages of anthropogenic pollen indicators, (2) increase of Ericaceae percentages, (3) low pollen percentages of Alnus, (4) high macrocharcoal concentrations and (5) high values of palynological richness during periods affected by the alnocoltura cycle according to the historical sources. Similar patterns are also detectable in pollen diagrams from two adjacent peat bogs. The paper shows the strength of an interdisciplinary methodology (field observations, cartographical and archival historical data, palynological and archaeological investigations) for studies of past land-use systems. By demonstrating the necessity of a long-term prospective in environmental reconstructions for the preservation of the cultural landscape, one of the important elements of this research is its potential contribution to issues of habitat management and nature-conservation policy. Further analyses are needed to test the replicability and reliability of the hypotheses derived from this study