Human-environment interactions during the Holocene in the Lake Banyoles area

Abstract

This study provides valuable information concerning the impact of Early and Mid-Holocene climate variability in sub-Mediterranean and Mediterranean lowland PrePyrenean regions, as well as vegetation responses against climatic oscillations occurred during the first half of the Holocene. The synthetic analysis of several pollen records from the coastal area of L'Empordà and the inland areas of Pla de l'Estany and La Garrotxa evidences expansion of forests during the Early Holocene in Northeastern Iberia, and the establishment of dense broadleaf deciduous forests during the Holocene Climate Optimum. Pollen records show the broadleaf deciduous trees forests resistance against cooling phases during the Mid-Holocene period, showing slight regressions of oak woodlands and expansion of conifers or xerophytic taxa contemporary to some cooling episodes (i.e. 8.2 and 7.2 cal ka BP). Major vegetation changes influenced by climate change occurred in the transition to the Late Holocene, in terms of the start of succession from broadleaf deciduous forests to evergreen sclerophyllous woodlands. Available radiocarbon dates evidence a gap in human presence in the region during the first half of the 8th millennium cal BP, with very few dates corresponding to the 9th millennium. In that sense, in the current state of knowledge we are unable to assess human-environment interactions during the Late Mesolithic. However, no direct relationship between climate change and this gap in human settlement dynamics can be established. The lack of evidence of previous occupation seems to support the Neolithisation of the NE Iberian Peninsula as a result of a process of migration of farming populations to uninhabited or sparsely inhabitated territories. In that context, remarkable changes in vegetation were recorded from 7.3 cal ka BP onwards in the Lake Banyoles area, where the establishment of permanent farming settlements caused the deforestation of oak woodlands. In La Garrotxa region, short deforestation episodes of broadleaf deciduous forests, together with expansion of grasslands and presence of Cerealia-type were documented in the period 7.4-6.0 cal ka BP. Finally, in the coastal area, where less evidence of Early Neolithic occupations is recorded, evidence of Neolithic impact is reflected in the presence of Cerealia-type in 6.5-6.2 cal ka BP, but no strong human transformation of landscape was carried out until more recent chronologies.