干旱区生态环境知识资源中心

The use of a high resolution pollen record in combination with geochemical data from sediments composed mainly of layers of charophytes alternating with layers of vegetal remains plus some detrital beds permits the reconstruction of the environmental evolution of the last 3000 years in an inland wetland of the Mediterranean domain, thus introducing a new climatic dataset for the Late Holocene. Hydrological fluctuations, reflected in the relationship between emerged and aquatic vegetation and inorganic and organic C and N changes, can be related to aridity or humid phases, while relations among arboreal taxa (Quercus and Pinus) and Artemisia are used as temperature indicators. Five climatic periods have been identified: a Subatlantic Cold Period (< 150 B.C.), cold and arid; the Roman Warm Period (150 B.C-A.D. 270), warmer and wetter; the Dark Ages (A.D. 270-A.D. 950), colder and drier; the Medieval Warm Period (A.D. 950-A.D. 1400), warmer and wetter; and the Little Ice Age (> A.D. 1400) indicated by a cooling and drying trend. Despite the lack of any direct evidence of human action, there are some episodes related to deforestation during the Reconquista (Middle Ages) that mask the real climatic signal.