Landscape dynamics and fire activity since 6740 cal yr BP in the Cantabrian region (La Molina peat bog, Puente Viesgo, Spain)

• There was a synergy between human action and climate regarding fires during Neolithic times.
• During the Bronze Age, decreased forest cover conditioned the fire events.
• A landscape like the present one has never existed before during the last 7000 years.
• The best analog of the recent local landscape is found during Neolithic times.
• Climate change has favored deciduous trees and led to an absence of Pinus during the Holocene.

A lack of paleobotanic studies with adequate resolution and multiproxy approaches has limited proper discussion of vegetation dynamics in Cantabria and of the role of fires in the configuration of the plant landscape during the Holocene in the northwest part of the Iberian peninsula. The pollen diagram of La Molina peat bog in Puente Viesgo (43°15′38″ N–3°58′37″ W; ETRS89), located at 484 m.a.s.l., and the study of its sedimentary charcoals allowed the acquisition of a continuous and thorough fire sequence for the last 6700 cal yr BP and an understanding of its relationship to the forest. The results show the importance of human influence on the incidence and characteristics of fire activity during the different phases studied: the Neolithic, Bronze Age, Iron Age, Roman period, and Middle Ages. A synergy seems to exist between dry climate periods (especially during Bond events 3 and 4) and a greater presence of biomass. As the Holocene advances, vegetation coverage clearly tends to decrease. This study provides key elements for understanding the role of fire activity in the forest dynamics of deciduous and evergreen Quercus, Corylus, Pinus, Fagus, and Alnus and demonstrates the strongly artificialized character of the present landscape.