Human impact on fire regimes in temperate Europe: tree ring reconstruction of fire sizes in Białowieża Forest

The spatial dimension of past fire regimes in European temperate forests remains insufficiently studied, despite its significance for understanding human influence on fire activity, the variability of historical fires, associated ecosystem dynamics, and implications for fire management and nature conservation, particularly in the context of ongoing climate change. We dendrochronologically reconstructed and analysed the minimum spatial extent of fires over the past four centuries in a 9.2 km² (920 ha) coniferous section of the Białowieża Forest, the best-preserved forest area in temperate Europe. Using tree ring data from cross-sections of 275 dead sample trees (Scots pine, Pinus sylvestris), we spatially reconstructed 82 fires between 1666 and 1946. Most fires (92%) spread beyond our study area. Fire size varied greatly, from events recorded at only one site (covering 1–200 ha) to those detected in more than half of the study area, thus exceeding 500 ha. The reconstructed ignition density of 3.2 fires per 100 km² (10,000 ha) per year was 10–100 times higher than the current lightning ignition density, indicating substantial human impact. Furthermore, analysis of temporal changes in the fire cycle revealed three periods of differing fire activity: 1670–1750, 1755–1840, and 1845–1955, which correspond to land use changes in the Białowieża Forest. Our results (Zin et al. 2022, Front Ecol Evol) highlight the importance of fire for the long-term ecosystem dynamics of the Białowieża Forest and the role of natural and anthropogenic disturbances in shaping temperate forests of Europe.