DescriptionReconstruction of past vegetation cover and agro-pastoral activities was originally assessed through pollen. Lake sediment DNA is an emergent tool offering great promises for paleoenvironmental as well as archeological studies, giving the access to taxa from the lake and the catchment even in absence of macrofossils. Thus, here lake sediment DNA sequencing approach targeting plants and mammals extra-cellular DNA was coupled with pollen data to i) ensure the robustness of the vegetation reconstruction, ii) compare the methods and finally iii) reconstruct the history of past agro-pastoral activities and landscapes. This approach was applied on lake sediments from a small mountain lake in the North French Alps (Lake La Thuile, 875 m asl). Results show that pollen and plant DNA data are complementary. Both methods recovered similar taxa but additional taxa were found only with either a method. Reconstruction of past vegetation covers well concords with both methods along all the chronosequence. However, some discrepancies were observed likely due to i) bias linked to specific sediment composition not favorable to the extra-cellular DNA binding and ii) to the difference in the mode of transfer and thus the origin of the DNA (run-off and soil erosion in the catchment) relative to the pollen (also wind transported). Results show important pastoral activities started at the Iron Age (2600 cal. yr BP). Cereal crops are recorded from the Medieval times (1600 yr cal. BP) and corresponds also to a deforestation. From this period, pig livestock is suggested by the appearance of DNA from Sus scrofa sp. From about 900 yr cal. BP, human activities were more diversified, particularly with the appearance of fruit gardens. Interestingly this period was concomitant with lake eutrophication. We conclude that DNA sequencing from sediment is an effective approach to access to a detail history of both past vegetation cover and human land use through the direct access to both plant and mammal data.
|11 Jun 2014 → 14 Jun 2014
|International Conference on Culture and Climate
- Lake sediment DNA