Land snail fauna and Holocene environmental changes in Mediterranean France: A digest from three representative sedimentary sequences

Abstract

The Holocene terrestrial malacofauna of the northern shore of the Mediterranean remains poorly known. Its importance however is twofold, first to better understand the recolonization of Europe by woodland snails from different kinds of glacial refugia, secondly to bring to light the development of Mediterranean ecosystems. This paper is based on molluscan analyses of three sedimentary sequences from a catchment basin near Aix-en-Provence, all of which being representative of the most common pedo-sedimentary and malacological postglacial successions in southeastern France. A special effort has been made to establish the chronology. The results first show the lasting of temperate steppes, lasting in places all the way into the Boreal period (∼9000 cal yr BP). Less open environments appeared soon after with assemblages including thermophilic species. The Boreal period shows unstable conditions in an open and heterogeneous woodland landscape. A malacofauna indicating true woodland developed during the Older Atlantic (∼8000 cal yr BP). Dominated by “semi-forest” snails, it still contained some xerophilic ones. These assemblages lost their true woodland character between ∼7000 and ∼6500 cal yr BP due to anthropogenic influence. An increase in human activity and merchandise flow within a more open landscape caused a progressive but deep turnover of land snail communities since the Early Neolithic. It must be admitted that, during the Holocene as a whole, Mediterranean ecosystems remained heterogeneous and frequently open. The human impact is such that it is difficult to discuss the role of climate since ∼7000 cal yr BP.