New pedoanthracological data for the long-term history of forest species at mid-high altitudes in the Queyras Valley (Inner Alps)

In the context of global change, the assessment of the past history and current dynamics of forest species is essential for improving our knowledge of the settlement and evolution of the present-day landscape. Several paleoecological approaches are well suited for reconstructing past landscapes and Holocene dynamics. Today, the subalpine forest of Queyras is composed primarily of larch, with lesser proportions of stone pine, mountain pine and fir. During the Holocene, the subalpine forest was subject to natural disturbances, particularly fires. By the end of the Atlantic period, human perturbations resulting from agro-sylvo-pastoral practices became an important factor, and this factor serves to explain the landscape dynamics and the dominance of certain woody species. In this study, a pedoanthracological approach was used to enhance existing knowledge of the history of forest species and to reach a good understanding of the processes that have shaped the current floristic assemblage.The results of the analyses of soil charcoal performed in this study provide the following new information: (i) a longer Holocene history for larch and stone pine, (ii) a lack of evidence for a natural presence of fir and (iii) a long-term history for Scots pine. The dates obtained reveal the early occurrence of recolonization by stone pine and larch following the last glaciation. The charcoals analyzed demonstrate the overall presence of stone pine, which is found throughout the studied history of the area. In terms of the changes presently occurring, among which both the abandonment of human land-use practices and climate change are especially important, the current conditions at mid-high altitudes might potentially allow the establishment of larch forests for a long period as preclimax ecosystems. The low frequency of fir in charcoal samples raises questions about the status and possible presence of fir in the past despite palynological evidence.