First Spatial Reconstruction of Past Fires in Temperate Europe Suggests Large Variability of Fire Sizes and an Important Role of Human-Related Ignitions

Abstract

The spatial component of past forest fires in temperate Europe has been little studied, despite the value of such data in quantifying human and natural factors driving fire activity and associated forest dynamics. Changes in fire regimes reported across a range of ecosystems call for a better understanding of variability in historic fires and may help define reference points that can be relied upon when discussing climate change effects. We provide the first dendrochronological reconstruction of historical fire sizes in Central Europe and analyze the minimum extent of fires during the last four centuries in a 9.2 km2 (920 ha) conifer-dominated section of Białowieża Forest, one of the largest continuous lowland forests of the subcontinent. We recorded 82 fires between 1666 and 1946, using 275 sample trees, while 92% of fires (76 out of 82) spread beyond the studied area. Fires varied considerably in size, from events recorded at only one site (1–200 ha) to fires recorded in more than half of the studied area, thus exceeding 500 ha in size. The fire cycle was 11 years over the whole study period, with three distinct periods revealed by the regime shift analysis. In the years 1670–1750, the fire cycle averaged 12 years. It shortened to 7 years between 1755–1840 and increased to 22 years over the 1845–1955 period. In comparison with present day data, the reconstructed fire density of 3.2 fires per 100 km2 (10 000 ha) and year exceeded lightning ignition density by one to two orders of magnitude, suggesting a significant contribution of human-related ignitions. Our results highlight the important role of fire disturbance in Białowieża Forest and provide critical baseline information to design biological conservation strategies for European forests.

Pyric herbivory in a temperate European wood‐pasture system

“…Pyric herbivory has since long been integrated into studies on the ecology and management of grassy ecosystems in many continents, but much less so in Europe and especially in the more temperate parts (Allred et al., 2011), where it has rarely been applied or even examined, despite recent studies showing that herbivory (Bakker et al., 2016; Kuijper et al., 2010; Svenning, 2002; Vera, 2000) and fire (Bond & Keeley, 2005; Feurdean et al., 2018; Niklasson et al., 2010; Svenning, 2002; Zin et al., 2022) have had a great impact on the European vegetation since the early Holocene. Compared with tropical grasslands and savannas, large wild grazing herbivores have been absent from European temperate grasslands since the extinction of Europe's wild cow, the Aurochs Bos primigenius , in 1627 and wild horse, the Tarpan Equus ferus gmelini , in 1909.…”

High-resolution data reveal a surge of biomass loss from temperate and Atlantic pine forests, contextualizing the 2022 fire season distinctiveness in France

“…This represents on average of 0.05 % of wildland area each year, with the majority (95 %) occurring in Mediterranean ecosystems which experience drier and warmer summers. In contrast, temperate forests in Europe are less prone to fires due to their humid and mild climate conditions and, consequently, receiving less attention by the fire science community (Zin et al, 2022). However, the 2022 fire season in Europe was particularly out of the norm compared to previous decades, characterized by a severe drought and heat waves leading to numerous extreme fire events and widespread burned areas throughout the western part of the continent (Rodrigues et al, 2023).…”