Human–landscape interactions in the Conquezuela–Ambrona Valley (Soria, continental Iberia): From the early Neolithic land use to the origin of the current oak woodland

The sedimentological, geochemical and palynological analyses performed in the Conquezuela palaeolake (41°11′N; 2°33′W; 1124ma.s.l.) provide a detailed, multiproxy palaeoenvironmental reconstruction in one of the key areas of inner Iberian Neolithic colonization. Combined with archaeobotanical and archaeological data from well-dated settlements along the Conquezuela–Ambrona Valley we investigate how environmental conditions may affect both socio-economic adaptations and livelihood strategies of prehistoric communities. The first evidences of early Neolithic occupation in the valley ca. 7250–6450calyrBP (5300–4500BC) coincided with the onset of a period (7540–6200calyrBP, 5590–4250BC) with higher water availability and warmer climate as alluvial environments were substituted by carbonate-wetland environments in the basin. The Conquezuela record supports an early Neolithic colonization of the inner regions of Iberia favored by warmer and humid climate features and with preferential settlement patterns associated to lakes. The maximum human occupation of the valley occurred during the mid–late Neolithic and Chalcolithic (6200–3200calyrBP, 4250–1250BC) as evidenced by the high number of archaeological sites. Although a number of hydrological oscillations have been detected during this period, the intense landscape transformation at basin-scale, leading to a deforested landscape, was largely a consequence of widespread farming and pastoral practices. Socio-economic activities during Bronze, Iron and Roman times modified this inherited landscape, but the second largest ecosystem transformation only occurred during Mediaeval times when a new agrarian landscape developed with the expansion of stockbreeding transhumance. The current vegetation cover characterized by patches of holm and marcescent oaks and fields reflects an intense human management combining both extensive herding with agrarian activities in order to transform the previous forested landscape into a dehesa-like system.