Recent Holocene palaeoenvironmental evolution in the central Ebro Basin (NE Spain)

Abstract

Evolutionary aspects of landscape are analysed from the geomorphological, palynological and archaeological study of a sector in the Central Ebro Basin (NE Spain). In this study we use four representative sites, each of them offering different information about the evolution of the landscape in which they are located. Together, the data allow for the reconstruction of general patterns concerning the Holocene palaeoenvironmental evolution, erosion processes and their genetic interpretation. Climatic factors alone do not explain the key features and profound transformations suffered by this landscape. More likely, they have been the response to the changes activated by human impact. Deforestation since the Neolithic period has given rise to spaces of difficult bio-edaphic recovery. Different erosive agents have been the main source of sediments that currently fill the bottoms of the depressions and plain valleys. Human communities since the Neolithic have modified the landscape sufficiently to be recorded palynologically. Several phases of accumulation and incision stages have been identified (post-Bronze regularisation, Iberian–Roman incision, Medieval accumulative–incisive stage and Actual incision). The importance that the “climatic factor” would have had on the mentioned sites, if without any human intervention in the exploitation of the environment, is still subject to debate. From a climatic point of view, these phases are a consequence of the occurrence of dry and wet periods. Thus, the evolution of the landscape in the Ebro Basin in relation to the human occupation during the Upper Holocene is explained by a succession of dynamic changes. These fluctuations would have been due to a combination of climatic conditions conducive to the triggering of erosive processes, along with the strengthening of them by humans due to their intervention in the environment.