Crops and weeds from the Estany de Montcortès catchment, central Pyrenees, during the last millennium: a comparison of palynological and historical records.

We use palynological and historical records to reconstruct the evolution of agricultural practices and their consequences on landscape development in a mid-elevation Pyrenean small lake catchment during the last millennium. A total of ten cultivated plants and eight weed taxa were recognised and their changes in time recorded in detail. Two main phases of agricultural development were identified, A1 (9th-14th centuries ad) and A2 (16th-19th centuries ad). A1 coincided with the medieval climate anomaly and began after a widespread loss of woodland by fire, as manifested in a decline of arboreal pollen from ~60 to ~30 %, which affected mainly the pine woods (~40 to ~10 %). This phase was characterised by cultivation of the cereals Secale and Triticum/Avena, with Plantago as the main weed, alternating with pastures dominated by Artemisia, in a ca. 60 year land-use rotation scheme. A1 also coincided with a feudal socio-economic system that replaced the shifting cultivation practices of the earlier inhabitants with intensive agriculture. This type of land use was interrupted by the onset of the Little Ice Age, coinciding with a great social crisis with wars and plagues, leading to the depopulation of the zone and the recovery of woodlands. The onset of A2 coincided with the Spanish monarchy of the modern age and was characterised by Cannabis cultivation, which attained a maximum in the post-modern age, at the transition between feudalism and capitalism. Hemp was mainly used to supply fibre to the Spanish navy and the cultivation of this plant was mandatory until the disestablishment of this navy in ad 1834. After this date, a second socio-economic crisis took place as a consequence of massive emigration to large cities, promoted by the growing industrialisation. The combination of fossil and historical evidence significantly improves palaeoecological reconstructions in areas under heavy human impact, which is useful to enhance historical soundness, to understand how modern landscapes have been shaped and also to disentangle natural causes of ecological change from human ones. [ABSTRACT FROM AUTHOR]