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1. Recurring cycles of ice and vegetation on Baffin Island, Nunavut

   Raynolds, Martha K; Bültmann, Helga; Kasanke, Shawnee A; Miller, Gifford; Raberg, Jonathan H (January 2025, Arctic antarctic and alpine research)

   Vegetation has recolonized the Arctic numerous times throughout the Holocene. The most recent retreat of glaciers on Baffin Island, Nunavut, has been since the Little Ice Age, due to anthropogenic warming. Retreating cold-based ice often uncovers ancient vegetation. Recently exposed plants can tell us about past plant communities and colonization rates, important information for parameterizing vegetation feedback in climate models. Here, we provide complete descriptions of vegetation communities recently exposed by two retreating ice caps on Baffin Island and compare them with modern vegetation in the surrounding areas. We found that the ancient vegetation was similar to current vegetation, meaning that the current vegetation had not significantly changed during the past several hundred years. Colonization of bare ground was evident and differed depending on the substrate (rock versus finer substrates), with saxicolous lichens colonizing rocks and acrocarpous mosses and liverworts colonizing areas with finer substrates. The mature communities differed at the two sites, mostly because of a warmer climate at the southern site. Vegetation colonization, especially of light-colored rocks, reduces albedo, but the process can take hundreds of years. Changes in plant community composition are likely to continue for thousands of years due to climate change and the arrival of new species. 

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2. Arctic shrub colonization lagged peak postglacial warmth: Molecular evidence in lake sediment from Arctic Canada

   https://doi.org/10.1111/gcb.14836  

   Crump, Sarah E.; Miller, Gifford H.; Power, Matthew; Sepúlveda, Julio; Dildar, Nadia; Coghlan, Megan; Bunce, Michael (October 2019, Global Change Biology)

   Abstract Arctic shrubification is an observable consequence of climate change, already resulting in ecological shifts and global‐scale climate feedbacks including changes in land surface albedo and enhanced evapotranspiration. However, the rate at which shrubs can colonize previously glaciated terrain in a warming world is largely unknown. Reconstructions of past vegetation dynamics in conjunction with climate records can provide critical insights into shrubification rates and controls on plant migration, but paleoenvironmental reconstructions based on pollen may be biased by the influx of exotic pollen to tundra settings. Here, we reconstruct past plant communities using sedimentary ancient DNA (sedaDNA), which has a more local source area than pollen. We additionally reconstruct past temperature variability using bacterial cell membrane lipids (branched glycerol dialkyl glycerol tetraethers) and an aquatic productivity indicator (biogenic silica) to evaluate the relative timing of postglacial ecological and climate changes at a lake on southern Baffin Island, Arctic Canada. ThesedaDNA record tightly constrains the colonization of dwarf birch (Betula, a thermophilous shrub) to 5.9 ± 0.1 ka, ~3 ka after local deglaciation as determined by cosmogenic¹⁰Be moraine dating and >2 ka later thanBetulapollen is recorded in nearby lake sediment. We then assess the paleovegetation history within the context of summer temperature and find that paleotemperatures were highest prior to 6.3 ka, followed by cooling in the centuries precedingBetulaestablishment. Together, these molecular proxies reveal thatBetulacolonization lagged peak summer temperatures, suggesting that inefficient dispersal, rather than climate, may have limited Arctic shrub migration in this region. In addition, these data suggest that pollen‐based climate reconstructions from high latitudes, which rely heavily on the presence and abundance of pollen from thermophilous taxa likeBetula, can be compromised by both exotic pollen fluxes and vegetation migration lags. 

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3. Ancient plant DNA reveals High Arctic greening during the Last Interglacial

   https://doi.org/10.1073/pnas.2019069118  

   Crump, Sarah E.; Fréchette, Bianca; Power, Matthew; Cutler, Sam; de Wet, Gregory; Raynolds, Martha K.; Raberg, Jonathan H.; Briner, Jason P.; Thomas, Elizabeth K.; Sepúlveda, Julio; et al (March 2021, Proceedings of the National Academy of Sciences)

   Summer warming is driving a greening trend across the Arctic, with the potential for large-scale amplification of climate change due to vegetation-related feedbacks [Pearson et al.,Nat. Clim. Chang.(3), 673–677 (2013)]. Because observational records are sparse and temporally limited, past episodes of Arctic warming can help elucidate the magnitude of vegetation response to temperature change. The Last Interglacial ([LIG], 129,000 to 116,000 y ago) was the most recent episode of Arctic warming on par with predicted 21st century temperature change [Otto-Bliesner et al.,Philos. Trans. A Math. Phys. Eng. Sci.(371), 20130097 (2013) and Post et al.,Sci.Adv. (5), eaaw9883 (2019)]. However, high-latitude terrestrial records from this period are rare, so LIG vegetation distributions are incompletely known. Pollen-based vegetation reconstructions can be biased by long-distance pollen transport, further obscuring the paleoenvironmental record. Here, we present a LIG vegetation record based on ancient DNA in lake sediment and compare it with fossil pollen. Comprehensive plant community reconstructions through the last and current interglacial (the Holocene) on Baffin Island, Arctic Canada, reveal coherent climate-driven community shifts across both interglacials. Peak LIG warmth featured a ∼400-km northward range shift of dwarf birch, a key woody shrub that is again expanding northward. Greening of the High Arctic—documented here by multiple proxies—likely represented a strong positive feedback on high-latitude LIG warming. Authenticated ancient DNA from this lake sediment also extends the useful preservation window for the technique and highlights the utility of combining traditional and molecular approaches for gleaning paleoenvironmental insights to better anticipate a warmer future. 

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4. Southern Baffin Island mean annual precipitation isotopes modulated by summer and autumn moisture source changes during the past 5800 years

   https://doi.org/10.1002/jqs.3390  

   Gorbey, Devon B.; Thomas, Elizabeth K.; Crump, Sarah E.; Hollister, Kayla V.; Raynolds, Martha K.; Raberg, Jonathan H.;  Wet, Gregory; Sepúlveda, Julio; Miller, Gifford H. (July 2021, Journal of Quaternary Science)

   Paleo water isotope records can elucidate how the Arctic water cycle responded to past climate changes. We analyze the hydrogen isotope composition (δ2H) of plant‐derived n‐alkanoic acids (waxes) from Lake Qaupat, Baffin Island, Nunavut, Canada, to assess moisture sources and seasonality during the past 5.8 ka. We compare this record to a sedimentary ancient DNA (sedaDNA)‐inferred vascular plant record from the same lake, aiming to overcome the uncertainty of plant community impacts on leaf waxes. As the sedaDNA record reveals a stable plant community after the colonization of Betula sp. at 6.1 ka, we interpret plant wax δ2H values to reflect climate, specifically mean annual precipitation δ2H. However, the distributions of n‐alkanoic acid homologs suggest that aquatic mosses, which are not represented in the sedaDNA record, may become more abundant towards the present. Therefore, we cannot exclude the possibility that changes in the plant community cause changes in the plant wax δ2H record, particularly long‐chain waxes, which become less abundant through this record. We find that Lake Qaupat mid‐chain plant wax δ2H is enriched coincident with high Labrador Sea summer surface temperature, which suggests that local moisture sources in summer and early autumn have the greatest impact on precipitation isotopes in this region. 

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5. Lake Qaupat, Baffin Island 5,800 Year Plant Wax and Geochemical Data

   https://doi.org/10.18739/A2X05XF4C  

   Gorbey, Devon; Thomas, Elizabeth K (April 2025, NSF Arctic Data Center)

   Paleo water isotope records can elucidate how the Arctic water cycle responded to past climate changes. We analyze the hydrogen isotope composition (δ2H) of plant‐derived n‐alkanoic acids (waxes) from Lake Qaupat, Baffin Island, Nunavut, Canada, to assess moisture sources and seasonality during the past 5.8 kiloannum (ka). We compare this record to a sedimentary ancient DNA (sedaDNA)‐inferred vascular plant record from the same lake, aiming to overcome the uncertainty of plant community impacts on leaf waxes. As the sedaDNA record reveals a stable plant community after the colonization of Betula sp. at 6.1 ka, we interpret plant wax δ2H values to reflect climate, specifically mean annual precipitation δ2H. However, the distributions of n‐alkanoic acid homologs suggest that aquatic mosses, which are not represented in the sedaDNA record, may become more abundant towards the present. Therefore, we cannot exclude the possibility that changes in the plant community cause changes in the plant wax δ2H record, particularly long‐chain waxes, which become less abundant through this record. We find that Lake Qaupat mid‐chain plant wax δ2H is enriched coincident with high Labrador Sea summer surface temperature, which suggests that local moisture sources in summer and early autumn have the greatest impact on precipitation isotopes in this region. 

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