Crossing forest thresholds: inertia and collapse in a Holocene sequence from south-central Spain

A Holocene palaeoecological sequence from Villaverde, south-central Spain, is presented. The pollen stratigraphy is used to infer past vegetation chan ges within a catchment area that represents the boundary between semi-arid, plateau and mountain vegetation. From c. 9700-7530 cal. yr BP, Pinus is do minant, probably as a result of a combination of a relatively dry climate a nd natural fire disturbance. From c. 7530-5900 cal. yr BP, moderate invasio n by Quercus appears to be a migrational response following increased moist ure and temperature, but in part shaped by competitive adjustments. From c. 5900-5000 cal. yr BP, the pine forests are replaced by deciduous-Quercus f orests with an important contribution from Corylus, Betula, Fraxinus and Al nus. Mediterranean-type forests spread from c. 5000 to 1920 cal. yr BP coin cident with expansions of Artemisia, Juniperus and other xerophytes. From c . 1920-1160 cal. yr BP, Pinus becomes dominant after a disturbance-mediated invasion of the oak forests. Human impact upon the regional landscape, was negligible during the Neolithic, and limited in the Bronze and Iron Ages. Local deforestation and the expansion of agro-pastoral activities occur aft er c. 1600 cal. yr BP.