Reconstructing Anthropocene dynamics of subtropical vegetation and plant diversity by combining sedimentary ancient...

Human-induced transitions in vegetation community and plant diversity have shown far-reaching ecological and socioeconomic consequences worldwide during the Anthropocene. Sedimentary ancient DNA (sedaDNA) is increasingly used to study paleoecological dynamics; however, this promising approach has never been directly compared with pollen records for subtropical floristic reconstruction, particularly in intensively modified landscapes. Here, we conducted high-resolution sedaDNA and pollen analysis on Lake Taihu sediment archives from the eastern China floodplain, together with contemporary surveys, to examine the evolutionary dynamics in the terrestrial and aquatic plant communities spanning the past hundred years. Terrestrial plant DNA was successfully amplified, and 57 taxa were well identified through the sediment core, but the molecular detection of aquatic macrophytes was subject to some issues associated with hydrological fluctuations and the reference library/primer used. The plant diversity recovered from sedaDNA showed a specific local signal and greater taxonomic resolution for crops and grasses related to cultivated land use, while the pollen records mainly captured regional terrestrial vegetation development especially forestry as well as mixed aquatic plant information mostly linked to littoral habitats. The results demonstrate that these two proxies are complementary rather than overlapping in the subtropical floodplain regions, and in combination reflect more detailed flora changes. Our comprehensive records reveal human-dominated terrestrial vegetation turnover and increase in diversity since the 1960s from the local to regional level. The succession and degradation of littoral aquatic plant community was probably attributed to hydrodynamic conditions and cultural eutrophication. Our finding highlights the broad prospects of combining morphological and molecular approaches for paleoecological research, and adds to the increasing evidence supporting that recent terrestrial and aquatic ecosystem dynamics are dominated by anthropogenic environmental changes.