Palaeoenvironmental studies allow the assessment of long-term human-climate-environmental interactions, and furnish valuable tools for the sustainable management of lacustrine ecosystems. A good example is the multi-proxy studythat of Lake Aydat’s 19 m sedimentary core. Previous research revealed the role of climate and human activities on lake sedimentation, and identified two sedimentary units (6700 ± 200 to 3180 ± 90 and 1770 ± 60 cal. yr BP to present) separated by an erosive mass-wasting deposit (Lavrieux et al., 2013a). Pollen, non-pollen palynomorphs (e.g. fungal and algal spores, rotifer resting eggs), and diatom-based trophic reconstructionshave been used to track the impacts of past land use on landscape evolution, vegetal biodiversity and water quality. Palaeoenvironmental data were also compared with local archaeo-historical datasets which allowed refined landscape reconstructions, especially for late Antiquity. The results obtained demonstrate that even Neolithic and Bronze Age human activities (between ca 4600 and 4300 cal. yr BP and between ca 3900 and 3500 cal. yr BP) had a discernible influence on catchment vegetation and lacustrine trophic dynamics of Lake Aydat, underlining the vulnerability of the ecosystem. Recurrent and complex models of past vegetation changes, phases of water nutrient over-enrichment and lake resilience were identified and related to grazing activities, but also to land use practises, which have been overlooked in Auvergne, such as mountain agriculture and hemp retting.
This study was supported by the Erode project funded by the INSU/CNRS (AP EC2CO 2009) and we thank ARTEMIS programme for AMS radiocarbon dating. Many thanks also to all the contributors to the Erode project. Finally we would like to thank Dr E. Roussel and Dr D. Latour who took the photographs and G. Charrier who drew the map. This manuscript has also benefitted from the comments of one anonymous reviewer and of Dr S. Leroy (Brunel University London).
- lake water quality
- human impact
- Rotifer resting eggs
- diatom-inferred trophic level