The sedimentary and remote‐sensing reflection of biomass burning in Europe

Abstract

Aim We provide the first European‐scale geospatial training set relating the charcoal signal in surface lake sediments to fire parameters (number, intensity and area) recorded by satellite moderate resolution imaging spectroradiometer (MODIS) sensors. Our calibration is intended for quantitative reconstructions of key fire‐regime parameters by using sediment sequences of microscopic (MIC from pollen slides, particles 10–500 µm) and macroscopic charcoal (MAC from sieves, particles > 100 µm). Location North–south and east–west transects across Europe, covering the mediterranean, temperate, alpine, boreal and steppe biomes. Time period Lake sediments and MODIS active fire and burned area products were collected for the years 2012–2015. Methods Cylinder sediment traps were installed in lakes to annually collect charcoal particles in sediments. We quantitatively assessed the relationships between MIC and MAC influx (particles/cm2/year) and the MODIS‐derived products to identify source areas of charcoal and the extent to which lake‐sediment charcoal is linked to fire parameters across the continent. Results Source area of sedimentary charcoal was estimated to a 40‐km radius around sites for both MIC and MAC particles. Fires occurred in grasslands and in forests, with grass morphotypes of MAC accurately reflecting the burned fuel‐type. Despite the lack of local fires around the sites, MAC influx levels reached those reported for local fires. Both MIC and MAC showed strong and highly significant relationships with the MODIS‐derived fire parameters, as well as with climatic variation along a latitudinal temperature gradient. Main conclusions MIC and MAC are suited to quantitatively reconstructing fire number and fire intensity on a regional scale. However, burned area may only be estimated using MAC. Local fires may be identified by using several lines of evidence, e.g. analysis of large particles (> 600 µm), magnetic susceptibility and sedimentological data. Our results offer new insights and applications to quantitatively reconstruct fires and to interpret available sedimentary charcoal records.

Wrong response

“…These analyses, however, show a strong dependency on vegetation type and fire regime and the need to apply calibrations accounting for charcoal source area in the 5 same way as for the interpretation of pollen abundances (Prentice, 1985: Sugita, 1994. Such calibrations have been made for Europe (Adolf et al, 2017). Our analyses establish that there is a relationship (R 2 = 0.77) between global charcoal abundance, expressed as normalized anomalies, and the methane isotopic record.…”

Unprecedented herbivory threatens rear‐edge populations of Betula in southwestern Eurasia

“…, Adolf et al. ), we also focus on charcoal influxes or accumulation rates (CHAR, no. particles·cm −2 ·yr −1 ).…”

“…sporesÁcm À2 Áyr À1 ) because, on the one hand, they are independent from changes in vegetation and sedimentation that may strongly bias percentages and concentrations, respectively, and, on the other hand, they show a highly significant correlation with local herbivore densities (Baker et al 2016). Concerning microscopic charcoal, a proxy for regional fire activity (10 4 m radii; Tinner et al 1998, Adolf et al 2018, we also focus on charcoal influxes or accumulation rates (CHAR, no. particlesÁcm À2 Áyr À1 ).…”

“…Finally, we produced high-resolution macroscopic charcoal series (contiguous subsamples at 1-cm intervals, Appendix S2) to reconstruct local to regional fire occurrence (10 1 -10 4 m radii; Higuera et al 2011, Adolf et al 2018. In this case, we mostly discuss CHAR values (no.…”

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“…The workshop gathered 18 participants from 12 countries, including 10 researchers from Africa-based institutions. It opened with introductory lectures and laboratory practical courses on study-site selection, sampling techniques, laboratory preparation and charcoal morphology analyses, and a discussion on charcoal calibration approaches for African sites (Ekblom and Gillson 2010;Adolf et al 2018;Hawthorne et al 2018; Fig. 1).…”