Dynamic land-plant carbon sources in marine sediments inferred from ancient DNA

Abstract

Terrigenous organic matter in marine sediments is considered a significant long-term carbon sink, yet our knowledge regarding its source taxa is severely limited. Here, we leverage land-plant ancient DNA from six globally distributed marine sediment cores covering the Last Glacial-Holocene transition as a proxy for the share, accumulation rate, preservation, and composition of terrigenous organic matter. We show that the spatial and temporal plant composition as revealed by sedaDNA records reflects mainly the vegetation dynamics of nearby continents as revealed by comparison with pollen from land archives. However, we also find indications of a global north-to-south translocation of sedaDNA. The plant composition shows that upland vegetation is strongly underrepresented in the record compared to riverine and coastal sources. We also find that plant sedaDNA has a higher accumulation rate in samples from the Late Glacial, which is characterized by high runoff and mineral load. Thus plant DNA in marine sediments allows for new perspectives on the global linkages between the terrestrial and marine carbon cycle which would benefit from a more quantitative understanding of DNA preservation and dispersal. This represents the basis of how climate change and land-use change translate into carbon-sink dynamics and also informs about natural carbon-capture solutions.