A MILLENNIUM OF MEDITERRANEAN FOREST HISTORY: COMPARING HUMAN IMPACTS AND CLIMATE CHANGE IN CENTRAL ITALY

A 1100 year sedimentary sequence from a lake in central Italy near Rome (Lago Lungo, Lazio, 379 m a.s.l.) was sampled for pollen and charcoal at an average interval of 26 years providing a high-resolution reconstruction of vegetation from 885 AD to the present. Pollen percentages support historical documents that describe periodic deforestation and agricultural expansion during the Medieval Climate Anomaly (MCA). Forests recovered about 1400 AD following depopulation associated with the black plague and socio-economic instability and a shift to cool wet climate during the Little Ice Age (LIA). Mixed deciduous forest reached a maximum in 1550 AD, approximately one century later than many sites across Western Europe. A less diverse less dense forest emerged after 1650 AD following the plague of 1656 AD. There is no evidence that excessive cutting, burning and erosion during the medieval period caused permanent degradation of the landscape. Forests appear to have recovered rapidly when land use declined and climate became favorable. Comparison of the pollen data with reconstructed Palmer Drought Severity Index (PDSI) of Morocco and North Atlantic Oscillation (NAO) indicate periods of deforestation and woodland regeneration coincide with climate change. During warm dry climate, deforestation accelerated and agriculture expanded, and during extended cool wet climate, conditions for cereal cultivation deteriorated, forests and wetland expanded, and the local agricultural system collapsed. These results show that in the Mediterranean, collapse of local agricultural systems may also occur during extended periods of cool/wet climate.