Vegetation dynamics and anthropogenically forced changes in the Estanilles peat bog (southern Pyrenees) during the last seven millennia
Résumé
Estanilles peat bog, located in the northeastern
Iberian peninsula,was studied to determine the anthropogenic
changes in the landscape over the past seven millennia. The
pollen diagram and sedimentary charcoal analyses from this
site permit us to reconstruct the landscape changes in an area
of both Mediterranean and Atlantic influence. In addition,
Montarenyo ombrotrophic peat bog was studied to strengthen
the analysis of data from more recent centuries. This paper
attempts a reconstruction of historical cultural landscapes
using two complementary palaeobotanical proxies (pollen and
charcoal) in high mountain environments. The macroscopic
charcoal record shows a fire signal since 7500 cal. B.P. However,
the relationship between fire frequency and human
impact is not always linear. This divergence is linked to fuel
availability and fire activity. Fire has been used repeatedly to
clear ground and to maintain open areas, and has been a key
tool for the management of these high mountain areas. The
intensity of use of the landscape implies the expansion of
agricultural areas into higher altitudes, including cereal cultivation
above 2,200 m a.s.l., during the Middle Ages. The
first clear human influence detected in the pollen percentage
data is recorded between 6000 and 7000 cal. B.P. and, until
present times, the greatest changes in vegetation and landscape
history occurred during periods of particular specialization
in socioeconomic activities during the Middle Ages.