BG2.6

The current main methodologies for identifying DNA fragments in ancient environmental samples are metabarcoding and shotgun sequencing which present strong advantages and limitations. Target capture is a promising method for enriching shotgun libraries for target organisms and might be able to combine the advantages from metabarcoding and shotgun sequencing into a single method. Target capture operates by hybridising DNA fragments in a sample to synthetic RNA-baits which share enough homology (≥85 %). These RNA-baits contain a magnetic molecule which is used to pull the hybridised fragments of interest to a magnet, allowing for the non-hybridised molecules to be washed away. The RNA-baits are designed according to prior knowledge of target sequences. Target capture does not require a PCR amplification step to amplify fragments using taxon-specific primers, and it might, therefore, be less prone to PCR amplification biases.

We designed a bait-set for capturing two barcoding plastidial genes matK and rbcL for all the species in four major plant orders: Asterales, Fagales, Pinales, and Poales. These orders are species-rich and/or difficult to identify to low taxonomic levels (family, genus or species) using metabarcoding. Our objectives were: 1) to design a universal method for trimming and selecting sequences for bait design using online sequence repositories, 2) to investigate a potential capture bias of species with a low GC-content (proportion of guanine and cytosine nucleotides) and 3) to investigate taxonomic resolution of target capture compared to metabarcoding. Because species with an overall low GC content (<32%) might be less efficiently captured than species with a higher GC content, we used mock communities with a known proportion of amplicons fragment size distribution and GC content. Further, we used sequence data simulations to investigate taxonomic resolution using varies species pools.

How to cite: Nota, K., Orlando, L., Marchesini, A., Girardi, M., Vernesi, C., and Parducci, L.: Shotgun barcode baiting: capturing barcoding genes from environmental samples for species identification, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13501, https://doi.org/10.5194/egusphere-egu21-13501, 2021.

Understanding patterns of colonisation is important for explaining both the distribution of single species and anticipating how ecosystems may respond to global warming. Insular flora may be especially vulnerable because oceans represent severe dispersal barriers. Here we analyse two lake sediment cores from Iceland for ancient sedimentary DNA to infer patterns of colonisation and Holocene vegetation development. Our cores from lakes Torfdalsvatn and Nykurvatn span the last c. 12,000 cal. yr BP and c. 8600 cal. yr BP, respectively. With near-centennial resolution, we identified a total of 191 plant taxa, with 152 taxa identified in the sedimentary record of Torfdalsvatn and 172 plant taxa in the sedimentary record of Nykurvatn. The terrestrial vegetation at Torfdalsvatn was first dominated by bryophytes, arctic herbs such as Saxifraga spp. and grasses. Around 10,100 cal. yr BP, a massive immigration of new taxa was observed, and shrubs and dwarf shrubs became common whereas aquatic macrophytes became dominant. At Nykurvatn, all dominant taxa occurred already in the earliest samples; shrubs and dwarf shrubs were more abundant at this site than at Torfdalsvatn. There was an overall steep increase both in the local and regional species pool until 8000 cal. yr BP, by which time ¾ of all taxa identified had arrived. In the period 4500-1000 cal. yr BP, a few new taxa of bryophytes, graminoids and forbs are identified. The last millennium, after human settlement of the island (Landnám), is characterised by a sudden disappearance of Juniperus communis, but also reappearance of some high arctic forbs and dwarf shrubs. Notable immigration during the Holocene coincides with periods of dense sea-ice cover, and we hypothesise that this may have acted as a dispersal vector. Thus, although ongoing climate change might provide a suitable habitat in Iceland for a large range of species only found in the neighbouring regions today, the reduction of sea ice may in fact limit the natural colonisation of new plant species.

How to cite: Alsos, I., Lammers, Y., Kjellman, S. E., Merkel, M. K. F., Bender, E. M., Rouillard, A., Erlendsson, E., Guðmundsdóttir, E. R., Benediktsson, Í. Ö., Farnsworth, W. R., Brynjólfsson, S., Gísladóttir, G., Eddudóttir, S. D., and Schomacker, A.: Ancient sedimentary DNA shows rapid post-glacial colonisation of Iceland followed by relatively stable vegetation until Landnám, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14474, https://doi.org/10.5194/egusphere-egu21-14474, 2021.

About 14,000 years ago, on the cusp of major environmental changes that affected the distribution of animals, vegetation cover and hydrology, humans entered interior Alaska for the first time.  A sedimentary ancient DNA (sedaDNA) record from a lake in the Tanana valley, which lies close to several of the oldest dated archaeological sites, documents plant community changes over the past ca. 15,000 years and makes an important contribution towards resolving late MIS-2 floristic composition of the northern, ice-free region of northwest North America.  Macroscopic charcoal and sediment properties provide further information on changes in climate and fire regimes.

For sedaDNA analysis, we amplified a short locus of the plant chloroplast genome in all samples, and a total of 167 vascular plant and 14 bryophyte taxa were detected in the lake sedaDNA record. A rich herbaceous flora, including taxa typical of open tundra habitats, dominates the record until ca. 14,000 cal yr BP; diverse grass taxa are present, and Salicaceae is recorded in every sample in this period. This flora continued (though with compositional changes) as a dominant element in the following period, which was also characterized by the presence of shrub and/or tree birch, and which ended with the establishment of coniferous forest ca. 10,000-11,000 yr BP. This last change is also reflected in sediment organic content, sedimentation rate, and the addition of a diverse range of shrubs, sub-shrubs, boreal forbs, spore-plants and aquatic macrophytes, all reflecting profound alterations in both terrestrial and lacustrine plant communities. Macro-charcoal is present in all floristic zones, with higher concentrations afterca. 14,000 yr BP, indicating that both deciduous and evergreen woody communities burned.  

This lake record provides a picture of key landscape-scale changes experienced by early human populations.SedaDNA results obtained from contemporaneous cultural and non-cultural layers at nearby archaeological sites in the Tanana Valley can provide further complementary information on natural resource use by early human communities in response to a changing environment. The loessal sediments at these archaeological sites present challenges to sedaDNA studies, including anthropogenic disturbance of the matrix, rootlet penetration, and unfrozen conditions for around four months of the year that may accelerate bacterial degradation and fragmentation of DNA. We present here some preliminary results from these archaeological localities.

How to cite: Edwards, M., Clarke, C., Bigelow, N., Heintzman, P., Potter, B., Alsos, I., and Reuther, J.: Late Quaternary vegetation dynamics in interior Alaska revealed by sedimentary ancient DNA (sedaDNA) from lake sediment and unfrozen (loessic) archaeological sediments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16451, https://doi.org/10.5194/egusphere-egu21-16451, 2021.

The eastern Tibetan Plateau, particularly the Hengduan Mountains and Sanjiangyuan region, is a biodiversity hotspot also known for its sensitivity to climate change. How these vegetation communities assembled since the Last Glacial Maximum is still unclear. Here we present new results from plant metabarcoding of sediments from Lake Ximencuo (Nianbaoyeze Mountains, Sanjiangyuan region) covering the last 18 ka and compare them with records from Lake Naleng (Hengduan Mountains).  We investigate temporal changes of within-site and between-site alpha and beta diversities. Both sites show the highest richness between 14 and 10 ka when alpine meadows covered the areas while richness was rather low in forested periods during the early Holocene. Ordination results support that the vegetation composition was relatively low between-site beta-diversities indicate that the vegetation composition was relatively similar in the two study areas before the Holocene, particularly during the early late-glacial when alpine steppes dominated. The maximal between-site beta-diversity occurred between 10 and 8 ka when environmental filtering was most relevant, as suggested by the dominating turnover component. The nestedness component of beta-diversity reached a maximum during the middle Holocene indicating that between-site differences during this period possibly originated from e.g., dispersal limitation.

How to cite: Shen, W., Liu, S., Stoof-Leichsenring, K. R., Courtin, J., Mischke, S., and Herzschuh, U.: Vegetation composition in Sanjiangyuan region compared with Hengduan Mountains (eastern Tibetan Plateau) since the Last Glacial Maximum revealed by plant metabarcoding of sedimentary ancient DNA, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13710, https://doi.org/10.5194/egusphere-egu21-13710, 2021.

Since the seminal paper in 1998 (Coolen and Overmann), sedimentary ancient DNA (sedaDNA) has become a powerful tool in paleoecology to reconstruct past changes in terrestrial and aquatic biodiversity. Still, sedaDNA is an emerging tool and there is a need for calibrations and validations to ensure the reliability of sedaDNA as a proxy to reconstruct past biota. One way to pursue this goal is by unifying the sedaDNA scientific community. Here, we present a few initiatives taken over the last years to transmit information, augment our knowledge about best practices and method standardisation related to sedaDNA analysis and strengthen collaborations between research groups. Also, we discuss tools and ideas that could be used to increase the visibility of sedaDNA research by the scientific community. Finally, we would like to use this opportunity to discuss with the audience about new strategies to unify experts from different research fields - including paleoecology, paleolimnology, paleoceanography, molecular ecology, aquatic ecology, terrestrial ecology, microbial ecology - around the use of sedaDNA.

How to cite: Capo, E. and the sedaDNA scientific community: Unifying the sedaDNA scientific community, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4697, https://doi.org/10.5194/egusphere-egu21-4697, 2021.

Arctic sea ice is declining at an unprecedented pace as the Arctic Ocean heads towards ice-free summers within the next few decades. Because of the role of sea ice in the Earth System such as ocean circulation and ecosystem functioning, reconstructing its past variability is of great importance providing insight into past climate patterns and future climate scenarios. Today, much of our knowledge of past sea-ice variability derives from a relatively few microfossil and biogeochemical tracers, which have limitations, such as preservation biases and low taxonomic resolution. Marine sedimentary ancient DNA (marine sedaDNA) has the potential to capture more of the arctic marine biodiversity compared to other approaches. However, little is known about how well past communities are represented in marine sedaDNA. The transport and fate of DNA derived from sea-ice associated organisms, from surface waters to the seafloor and its eventual incorporation into marine sediment records is poorly understood.  Here, we present results from a study applying a combination of methods to examine modern and ancient DNA to material collected along the Northeast Greenland Shelf. We characterized the vertical export of genetic material by amplicon sequencing the hyper-variable V4 region of the 18S rDNA at three water depths, in surface sediments, and in a dated sediment core.  The amplicon sequencing approach, as currently applied, includes some limitations for quantitative reconstructions of past changes such as primer competition, PCR errors, and variation of gene copy numbers across different taxa. For these reasons we quantified amplicons from a single species, the circum-polar sea ice dinoflagellate Polarella glacialis in the marine sedaDNA, using digital droplet PCR. The results will increase our understanding on the taphonomy of DNA in sea ice environments, how sedimentation differs among taxonomic groups, and provide indications to potentially useful marine sedaDNA-based proxies for climate and environmental reconstructions.

How to cite: Harðardóttir, S., Lovejoy, C., Seidenkrantz, M.-S., and Ribeiro, S.: Sea ice protists in arctic marine sedaDNA records: origins, diversity, and vertical export of DNA from the sea surface to the seafloor, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8030, https://doi.org/10.5194/egusphere-egu21-8030, 2021.

How to cite: Giguet-Covex, C., Bajard, M., Chen, W., Walsh, K. J., Rey, P.-J., Messager, E., Etienne, D., Sabatier, P., Ficetola, F. G., Gielly, L., Blanchet, C., Guffond, C., Arnaud, F., and Poulenard, J.: Mountain agro-ecosystems long-term trajectories in the North Western Alps, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6072, https://doi.org/10.5194/egusphere-egu21-6072, 2021.

The increase in plant species richness in the Alps over the last century has been described as a direct response to climate warming. Alpine ecosystems are expected to have an upward displacement of vegetation, resulting in shifts of species ranges, high replacement rates, and species loss. To apply proper management measures, it is necessary to understand how drivers of change affect species and ecosystem tipping points. Palaeoecological studies allow us to understand how species responded to similar situations in the past. However, such studies are often challenged by proxy preservation and taxonomic resolution. Metabarcoding approaches based on sedimentary ancient DNA (sedaDNA) can overcome these caveats. 

Here we use plant sedaDNA and the new PhyloAlps taxonomic reference database, which covers 4500 plant taxa from the Alps, to explore alpine floral diversity of Sulseewlii, a subalpine lake in the Central Alps (Switzerland). We present a 12,000 year record of vegetational composition and structural changes in a subalpine ecosystem. To disentangle the relationship between climate and vegetation, we used a novel local temperature reconstruction inferred from chironomids of the same lake. We also used coprophilous fungal spores and charcoal, together with pastoral and arable indicators, to infer human pressure. 

With 377 identified taxa, including 140 at species level, Sulseewlii has yielded the richest dataset of plant sedaDNA to date and emphasizes the Alps as an important biodiversity hotspot in Europe. Out of the identified taxa, 91 are indicators that allowed us to reconstruct the vegetation stages and altitudinal shifts of the main vegetation groups. Total taxonomic richness increases from the onset of the Holocene and has a similar pattern to subalpine-montane DNA taxa, with three marked drops at 8200, 3200, and ~500 cal yr BP. Plant sedaDNA registered a marked transition from alpine to subalpine communities at the onset of the Holocene. The highest proportions of montane taxa occurred during the Holocene climatic optimum (9,000-6,000 cal yr BP). Finally, a shift back to subalpine-montane species with some lowland influence occurs as we approach the present.

How to cite: Garces Pastor, S., Lammers, Y., Heintzman, P. D., Gavin Brown, A., Tinner, W., Schwörer, C., Heiri, O., Rey, F., Heer, M., Rutzer, A., Lavergne, S., Coissac, E., Taberlet, P., Theurillat, J.-P., and G. Alsos, I.: Exceptionally rich sedaDNA record from a subalpine lake in the Central Alps reveals plant responses to climate change and human land use, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15285, https://doi.org/10.5194/egusphere-egu21-15285, 2021.

The multitude of factors alleged to have contributed to the late Quaternary mass extinction of some two-thirds of Earth’s megafauna is complicated by the coarse record of buried macro-fossils. In response, micro-methods such as ancient DNA have been increasingly able to augment discontinuous palaeontological records to investigate the relative timings of vegetation turnover versus megafaunal extirpations—all in the absence of biological tissues. Here, we present sedimentary ancient DNA data retrieved using the PalaeoChip Arctic-1.0 bait-set diachronically identifying fauna and flora from permafrost cores recovered from the Klondike region of central Yukon, Canada dating between 30,000–6000 calendar years BP. We observe a substantial turnover in ecosystem composition between 13,000–10,000 BP with the rise of woody shrubs and the disappearance of mammoth-steppe vegetation. We also identify a lingering signal of Equus sp. (North American horse) and Mammuthus primigenius (woolly mammoth) from multiple samples thousands of years after their last dated macro-fossils, possibly as late as the mid-Holocene.

How to cite: Murchie, T. J., Monteath, A. J., Long, G. S., Karpsinski, E., Cocker, S., Zazula, G., MacPhee, R., Froese, D., and Poinar, H.: Ecological turnover and megafaunal ghost ranges during the Pleistocene-Holocene transition in central Yukon, Canada as revealed by palaeoenvironmental DNA, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-372, https://doi.org/10.5194/egusphere-egu21-372, 2021.

The Alps contain highly biodiverse ecosystems including a large number endemic flora. As a result of climate change and anthropogenic activities, such ecosystems are at risk from upward vegetation displacement and species loss. Extensive archaeological research in the Eastern Alps has documented human settlement from ~5500 years ago driven by salt and copper mining; which has caused significant impact on the ecosystems through mining, deforestation, and pastoral farming. To elucidate the effects of climate change and anthropogenic activities on plant biodiversity, multi-proxy reconstructions have been carried out throughout the Western Alps . Despite this research, the palaeoecological history of the Eastern Alps is relatively understudied. Consequently, we are limited in our understanding of how climate change and human impact have affected past biodiversity and the formation of the contemporary vegetation in this region. Here, we focus on the Austrian sub-alpine lake, Großer Winterleitensee located at the Easternmost margin of the Alps; only locally glaciated during the Pleistocene. We applied sedimentary ancient DNA (sedaDNA) metabarcoding to reconstruct Holocene plant community dynamics within the lake catchment. These data, in conjunction with local temperature reconstructions, sediment elemental composition, magnetic susceptibility, and loss-on-ignition analyses, allowed us to identify key intervals of plant diversity change. Two such intervals begin at samples dated ~5500 cal. yr BP and ~2200 cal. yr BP, coinciding with Neolithic and Iron Age settlement phases in the area. Palaeoecological reconstructions of plant biodiversity and their responses to climate change and anthropogenic pressures may be able to provide essential information for future conservation purposes.

How to cite: Zetter, S., Garcés Pastor, S., Lammers, Y., Tribsch, A., Brown, A. G., Coissac, E., Lavergne, S., Heintzman, P. D., and Alsos, I. G.: Holocene reconstruction of plant communities and impacts of human activity from sedaDNA in the Austrian Alps., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15432, https://doi.org/10.5194/egusphere-egu21-15432, 2021.

Lake sedimentary DNA (sedDNA) is an established tool to trace past changes in vegetation composition and plant diversity. However, little is known about the relationships between sedimentary plant DNA and modern vegetational and environmental conditions. In this study, we investigate i) the relationships between the preservation of sedimentary plant DNA and environmental variables, ii) the modern analogue of ancient plant DNA assemblages archived in lake sediments, and iii) the usability of sedimentary plant DNA for characterization of terrestrial and aquatic plant composition and diversity based on a large dataset of PCR-amplified plant DNA data retrieved from 259 lake surface sediments from the Tibetan Plateau and Siberia. Our results indicate the following: i) Lake-water electrical conductivity and pH are the most important variables for the preservation of plant DNA in lake sediments. We expect the best preservation conditions for sedimentary plant DNA in small deep lakes characterized by high water conductivities (≥100 μS cm^-1) and neutral to slightly alkaline pH conditions (7–9). ii) Plant DNA metabarcoding is promising for palaeovegetation reconstruction in high mountain regions, where shifts in vegetation are solely captured by the sedDNA-based analogue matching and fossil pollen generally has poor modern analogues. However, the biases in the representation of some taxa could lead to poor analogue conditions. iii) Plant DNA metabarcoding is a reliable proxy to reflect modern vegetation types and climate characteristics at a sub-continental scale. However, the resolution of the trnL P6 loop marker, the incompleteness of the reference library, and the extent of sedDNA preservation are still the main limitations of this method. iv) Plant DNA metabarcoding is a suitable proxy to recover modern aquatic plant diversity, which is mostly affected by July temperature and lake-water conductivity. Ongoing warming might decrease macrophyte richness in the Tibetan Plateau and Siberia, and ultimately threaten the health of these important freshwater ecosystems. To conclude, sedimentary plant DNA presents a high correlation with modern vegetation and may therefore be an important proxy for reconstruction of past vegetation.

How to cite: Jia, W., Stoof-Leichsenring, K., Liu, S., Li, K., Huang, S., Liu, X., Ni, J., Cao, X., Pestryakova, L., Mischke, S., and Herzschuh, U.: Metabarcoding of modern sedimentary DNA from the Tibetan Plateau and Siberia as a training dataset for vegetation reconstructions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14835, https://doi.org/10.5194/egusphere-egu21-14835, 2021.

For decades, paleoecological studies in lake sediments have focused on reconstructing the environments of the past and explaining phenomena linked to climatic variations. Recent advances in high-throughput DNA sequencing have allowed access to environmental DNA (eDNA) and ancient sedimentary DNA (sedaDNA) as a new and efficient proxy for past and present biodiversity. The basin of Mexico (BM) is located in the central part of the Trans-Mexican Volcanic Belt at 2,200 m a.s.l.; with the southern portion harboring the Chalco sub-basin. Lake Chalco is one of the last remaining natural aquatic ecosystems within the ever-expanding urban area surrounding Mexico City. The paleoenvironmental history of this lake has been previously characterized using sedimentological and geochemical proxies, as well as preserved microfossils (diatoms, pollen) with a temporal framework based on multiple radiocarbon dates. However, information for the remaining taxonomic groups and metabolic pathways remained unexplored. Here, we present the first metagenomics-based study for the Holocene in a high-altitude lake in Central Mexico –Lake Chalco. We explored the relationship between the lake’s paleoenvironmental condition and estimations of taxonomic and metabolic profiles across the sedimentary sequence (2.5 meters long). Multiple biological and abiotic variables revealed three main environmental phases: 1) a cool freshwater lake (FW1: 11,500-11,000 cal years BP), 2) a warm hyposaline lake (HS2: 11,000-6,000 cal years BP), and 3) a temperate, subsaline lake (SS3, <6,000 cal years BP). We describe the structure of the microbiota community and taxonomy richness turnover in the three Holocene paleoenvironmental phases. During the past 12 000 years BP the most abundant domains in Lake Chalco sediments were Bacteria, followed by Archaea, and Eukarya (36,722 genera). The analysis of functional proteins showed high biodiversity with a total of 27,636,243 proteins identified, but it was only possible to annotate 3,227,398 of them. Also, we identified several genes associated with some relevant pathways, such as methanogenesis. Altogether, this study allowed us to reconstruct the natural history of lake Chalco and its surroundings.

How to cite: Moguel, B., Pérez, L., Alcaraz, L. D., Lozano-García, S., Herrera-Estrella, L., Blaz, J., Caballero, M., Ávila-Arcos, M., Laclette, J. P., Muñoz-Velasco, I., Ortega-guerrero, B., Becerra, A., and Romero-Oliva, C.: Past and recent biodiversity profiling in ancient Lake Chalco Mexico by a metagenomics analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6277, https://doi.org/10.5194/egusphere-egu21-6277, 2021.

Siberian larch forests dominate large areas of northern Russia and contribute important roles for the world´s ecosystem. In order to understand the past dynamics of larches and their adaptive genetic variation, sedimentary ancient DNA (sedaDNA) extracted from lake sediment cores is a crucial source of genetic material. The difficulty of retrieving extremely rare DNA sequences from samples reaching back up to 25000 years in age, is challenging. Previous studies (Schulte et al.) showed that the hybridization capture allowed an enrichment of targeted sequences by several orders of magnitude in comparison to shotgun sequencing method. Therefore, we established for the first time, a hybridization capture method targeting 65 candidate adaptive genes laying on the Larix nuclear genome. Our preliminary results showed the ability of our newly established method to enrich extremely rare DNA sequences of the targeted Larix candidate adaptive genes, which were not retrieved by shotgun sequencing method applied on the same samples. Furthermore, the results allowed to detect and compare specific nucleotide polymorphism of adaptive candidate genes among sedaDNA samples distributed in space and time. The establishment of this new method is laying the basis to investigate possible adaptive variation of larch species acquired across the dry and cold conditions of the Last Glacial Maximum (LGM); as well as their possible advantages or disadvantages in relation to the current environmental changes toward dry and warm conditions.

How to cite: Meucci, S., Schulte, L., Stoof-Leichsenring, K. R., Kruse, S., Krutovsky, K., and Herzschuh, U.: Hybridization capture of Larix candidate adaptive genes from sedimentary ancient DNA., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15995, https://doi.org/10.5194/egusphere-egu21-15995, 2021.

One of the consequences of the amplified warming of the arctic ecosystems is tundra “greening” and northward expansion of Siberian boreal forests. However, it is still challenging to predict how northern tundra biodiversity will change with the ongoing climate warming as models usually overestimate forest invasion. The investigation of Quaternary records spanning different Pleistocene glacial and interglacial cycles can provide unique insights on past diversity dynamics following forest invasion and retreat events. Therefore, by “looking backward to look forward“, reconstruction of past vegetation can help to forecast the effects of global warming on northern biodiversity.

In 2017, a 46 m core was recovered from the Lake Levinson Lessing located in the tundra of the far north Taymyr Peninsula (northern Central Siberia), the upper 38 m of which span the last 62ka continuously and with a rather constant sedimentation rate. A high resolution of 84 subsamples were collected from the lake sediment core with the aim to characterise biodiversity changes between glacials and interglacials in Russian Arctic during Late Quaternary. We studied pollen and non-pollen-palynomorphs and extracted the ancient DNA (sedaDNA), from the same sediment core samples. We also investigated past vegetation composition changes by a plant metabarcoding approach (chloroplast trnL P6 loop). We compared both pollen and sedaDNA signals to reconstruct changes in biodiversity in the Taymyr Peninsula emphasizing changes in diversity during forest invasion and retreat events.

How to cite: Courtin, J., Schulte, L., Andreev, A., Stoof-Leichsenring, K., Lenz, M., Melles, M., and Herzschuh, U.: Effects of forest invasion and retreat on tundra biodiversity inferred from sedimentary ancient DNA of lake Levinson Lessing, Taymyr Peninsula, Russia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14218, https://doi.org/10.5194/egusphere-egu21-14218, 2021.

The colonization of recently deglaciated landscapes by tundra vegetation during the early Holocene is an important case study for understanding possible rates and patterns of plant migration in a rapidly warming world. Fossil pollen in lake sediment has traditionally served as the primary tool for reconstructing paleovegetation and understanding postglacial biogeography. However, because pollen can be wind-transported long distances and, in some cases, reworked from older deposits on the landscape, pollen-based vegetation histories can sometimes obscure the true history of plant colonization. In contrast, lacustrine sedimentary ancient DNA (sedaDNA) is sourced locally and is less likely to be adequately preserved through reworking events, thus making it a more reliable proxy for determining the precise timing of plant colonization. Here, we present three sedaDNA records from Holocene lake sediment across southern Baffin Island, Arctic Canada, that clarify the timing of postglacial vegetation changes. In particular, DNA from the subarctic shrub Betula (dwarf birch) first appears thousands of years after deglaciation in all three lake catchments, suggesting delayed colonization despite its strong pollen signal in early postglacial sediments. While moderate levels of Alnus (alder) pollen characterize early to mid-Holocene lake sediments from the region, sedaDNA suggests that Alnus was likely not present in any of the three lake catchments during the Holocene. In addition, aquatic plant community changes indicated by sedaDNA faithfully reflect the timing of early Holocene warmth in the region, highlighting the potential utility of aquatic plant DNA as a qualitative temperature proxy. We suggest that ancient plant DNA in lake sediment provides key paleoecological information that is distinct from traditional proxy records, particularly during periods of relatively rapid ecological change like the early Holocene. 

How to cite: Crump, S. E., Power, M., Fréchette, B., de Wet, G., Raynolds, M. K., Raberg, J. H., Allentoft, M., Bunce, M., and Miller, G. H.: Patterns of postglacial vegetation establishment clarified by lacustrine sedaDNA from Baffin Island, Arctic Canada, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10391, https://doi.org/10.5194/egusphere-egu21-10391, 2021.