Historia del fuego y la vegetación en una secuencia holocena del Pirineo central: la Basa de la Mora

Abstract

The importance of studying past fire regimes is derived from the need to understand the effects of current Global Change on present and future fire activity. Studying the relationship between long-term fire ecology, ecosystems and climate allows us to understand how vegetation responds to this perturbation and to define the thresholds triggering irreversible changes in the vegetation. This work presents the last 10 000 years of vegetation change and fire activity on a high altitude ecosystem from the Pyrenees range: the mountain lake Basa de la Mora located in the central southern Pyrenees. Holocene fire activity has been inferred through fossil carbon particle identification in the sedimentary sequence obtained in this lake. We observe that the strongest Holocene fire activity in the area occurred between 8.1 and 4 cal Kyr BP. This period was followed by a phase, between 3.2 and 1.7 cal Kyr BP, where almost no fire activity was recorded. These changes seem to be due to biomass availability and fire-conductive climate conditions. Positive correlation has been found between fire activity and Betula, Corylus, as the key fueling taxa and groups of ariditytolerant taxa. Additionally, fire dynamics seems coupled to higher anthropogenic activities after 1.7 cal Kyr BP.