Abstract
Wildfire occurrence is influenced by climate, vegetation and human activities. A key challenge for understanding the risk of fires is quantifying the mediating effect of vegetation on fire regimes. Here, we explore the relative importance of Holocene land cover, land use, dominant functional forest type, and climate dynamics on biomass burning in temperate and boreo-nemoral regions of central and eastern Europe over the past 12 kyr. We used an extensive data set of Holocene pollen and sedimentary charcoal records, in combination with climate simulations and statistical modelling. Biomass burning was highest during the early Holocene and lowest during the mid-Holocene in all three ecoregions (Atlantic, continental and boreo-nemoral) but was more spatially variable over the past 3-4 kyr. Although climate explained a significant variance in biomass burning during the early Holocene, tree cover was consistently the highest predictor of past biomass burning over the past 8 kyr. In temperate forests, biomass burning was high at ∼ 45% tree cover and decreased to a minimum at between 60% and 70% tree cover. In needleleaf-dominated forests, biomass burning was highest at ∼60 %-65%tree cover and steeply declined at > 65% tree cover. Biomass burning also increased when arable lands and grasslands reached ∼15 %-20 %, although this relationship was variable depending on land use practice via ignition sources, fuel type and quantities. Higher tree cover reduced the amount of solar radiation reaching the forest floor and could provide moister, more wind-protected microclimates underneath canopies, thereby decreasing fuel flammability. Tree cover at which biomass burning increased appears to be driven by warmer and drier summer conditions during the early Holocene and by increasing human influence on land cover during the late Holocene. We suggest that longterm fire hazard may be effectively reduced through land cover management, given that land cover has controlled fire regimes under the dynamic climates of the Holocene.
| Original language | English |
|---|---|
| Pages (from-to) | 1213-1230 |
| Number of pages | 18 |
| Journal | Biogeosciences |
| Volume | 17 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 4 Mar 2020 |
Funding
Acknowledgements. TraCE-21ka was made possible by the DOE INCITE computing program and supported by NCAR, the NSF P2C2 program, and the DOE Abrupt Change and EaSM programs. We thank Marc Metzger for providing the environmental stratification of Europe and Olivier Blarquez for guidance with the paleofire package. This study is based on the PAGES Global Charcoal Database (https://www.paleofire.org, last access: 22 February 2020) initiative developed by the Global Paleofire Working Group phase 2 (https: //www.paleofire.org/index.php, last access: 24 February 2020), which in turn received support from the US National Science Foundation and the Swiss Academy of Sciences. This database is hosted and funded by the Chrono-environment laboratory at the University of Burgundy Franche-Comté (France). Data consolidation was undertaken during a PAGES-funded workshop in 2016 in Frankfurt, Germany. by the German Research Foundation (grant nos. FE-1096/4-1 and FE-1096/6-1). Additional financial support also came from the Slovenian Research Agency (grant nos. P6-0064 and J7-6857); the UEFISCDI in Romania (grant no. PN-III-P4-ID-PCE-2016-0711); the Research Council of Lithuania (grant no. S-MIP-17-133); the Swiss Government Excellence Postdoctoral Scholarship (grant no. FIRECO 2016.0310); the National Science Centre in Poland (grant nos. 2015/17/B/ST10/01656 and 2015/17/B/ST10/03430); the Czech Science Foundation (grant nos. 16-06915S, 19-14271Y and GA14-22658S); the Estonian Research Council (grant no. PRG323); the Czech Academy of Sciences (grant no. RVO 67985939); the ANR OBRESOC project (grant no. ANR 09-CEP-004-01); and the Hungarian National Research, Development and Innovation Office (grant nos. NKFIH 101362 and GINOP-2.3.2-15-2016-00019). The publication of this article was funded by the Open Access Fund of the Leibniz Association.
