Fire history and the relationship with late Holocene anthropogenic activity in Tăul Mare peat bog in the Lăpuș Mts (Eastern Carpathians). Romania

Predicted climate warming and increasing anthropogenic pressure on environmental resources are expected to increase wildfire risk in Central and Eastern Europe (including Romania) and thus may affect areas currently outside fire risk areas. Therefore, knowledge of the natural and anthropogenic variability of wildfire, as well as its long-term impacts on the environment can provide an important perspective and be used to enhance the environmental management of this region.

Our study aims to reconstruct fire history in relation to anthropogenic disturbances and climate variability, over the last 2000 years in a now forested but former mining area from Lăpuș Mts (Eastern Carpathians, Romania) based on an ombrotrophic peat sequence. To reconstruct past fire activity, we employed sedimentary macroscopic charcoal (counts and morphological characteristics), a widely used proxy for gaining insight into long-term fire history and vegetation burning. Ombrotrophic peat bogs are sensitive to local environmental changes and, given that the deposition of allochthonous material is exclusively atmospheric, they are ideal archives for recording charcoal fluxes resulted from vegetation burning. Past local soil/bedrock erosion and regional atmospheric pollution from (pre)historical mining were reconstructed on the basis of abiotic sediment properties such as elemental geochemistry, mineral magnetic characteristics, organic matter content and particle size. Published sources were used to extract information regarding regional climate variability and extra-local to regional vegetation history.

Results show that increases in macro-charcoal concentration, particularly the woody charcoal morphotype, were shortly followed by marked increases in heavy metal concentration and by enhanced soil and bedrock erosion, as inferred from geochemical, magnetic and grain-size proxies. This suggests increased local disturbance during intervals with mining activities and indicates the likelihood that humans used fire to clear the forests and open the access to the mining sites. Alternatively, humans could have deforested the landscape to obtain charcoal in kilns, for ore smelting. Such actions likely resulted in topsoil removal and exposed bedrock surfaces, which is supported by the increase in the concentration of detrital elements and small, topsoil-derived magnetic particles in our record. Over recent centuries, the recovery of the local environment is evident in the proxies, with low fire activity and decreased soil/bedrock erosion, which coincides with the abandonment of the mining sites. This multi-proxy study shows the impact of anthropogenic disturbances and the recovery of the local environment and can be used to predict future possible responses of the local environment to stressors.