Deglaciation and catchment ontogeny in coastal south‐west Greenland: implications for terrestrial and aquatic carbon cycling
22
Citation
58
Reference
10
Related Paper
Citation Trend
Abstract:
Abstract Here we present Holocene organic carbon, nitrogen, sulphur, carbon isotope ratio and macrofossil data from a small freshwater lake near Sisimiut in south‐west Greenland. The lake was formed c. 11 cal ka BP following retreat of the ice sheet margin and is located above the marine limit in this area. The elemental and isotope data suggest a complex deglaciation history of interactions between the lake and its catchment, reflecting glacial retreat and post‐glacial hydrological flushing probably due to periodic melting of local remnant glacial ice and firn areas between 11 and 8.5 cal ka BP. After 8.5 cal ka BP, soil development and associated vegetation processes began to exert a greater control on terrestrial–aquatic carbon cycling. By 5.5 cal ka BP, in the early Neoglacial cooling, the sediment record indicates a change in catchment–lake interactions with consistent δ 13 C while C/N exhibits greater variability. The period after 5.5 cal ka BP is also characterized by higher organic C accumulation in the lake. These changes (total organic carbon, C/N, δ 13 C) are most likely the result of increasing contribution (and burial) of terrestrial organic matter as a result of enhanced soil instability, as indicated by an increase in Cenococcum remains, but also Sphagnum and Empetrum . The impact of glacial retreat and relatively subdued mid‐ to late Holocene climate variation at the coast is in marked contrast to the greater environmental variability seen in inland lakes closer to the present‐day ice sheet margin. Copyright © 2012 John Wiley & Sons, Ltd.Keywords:
Deglaciation
Macrofossil
Last Glacial Maximum
Cite
Macrofossil
Cite
Citations (4)
Macrofossil
Tree line
Scots pine
Betula pubescens
Holocene climatic optimum
Cite
Citations (61)
Abstract Paleoclimate reconstructions based on biological proxies present methodological challenges, especially during non-analog conditions, such as the early Holocene. Here, two chironomid-based training sets from Finland were amalgamated to create a more accurate transfer function of summer air temperature. The aim was to reconstruct Holocene paleoclimate in northernmost Lapland, in an area that has been either too warm or too cold for reliable reconstructions using the original calibration models. The results showed that the combined calibration model had improved performance statistics. The temperature trends inferred from the downcore chironomid record using the original and combined models were very similar. However, there were major changes in their absolute values with the combined model showing greatly improved accuracy. The chironomid-based temperature reconstruction showed significant correlation with the previous pollen-based reconstructions from northwestern Finnish Lapland. However, differences were observed in the temperature trends of the early Holocene, when the chironomid-inferred temperatures rapidly increased, but the pollen-based reconstructions lagged behind suggesting that a cool climate continued for much longer. However, similar to the chironomid record, new plant macrofossil evidence from northwestern Finland also showed warmer-than-present early Holocene temperatures. Therefore, we conclude that the early Holocene was probably warm in northern Lapland.
Macrofossil
Paleoclimatology
Subarctic climate
Holocene climatic optimum
Cite
Citations (58)
The data file presents information on the quantitative taxa distribution for plant macrofossils in the Holocene sediment cores of mires in the Kaliningrad region (Russian Federation, South-Eastern Baltic Region), as well as 24 radiocarbon dates (14C). The dataset contains percentages of 51 most common (more than 1%) taxa in 1361 samples of 45 sediment cores. These data provide information on environmental development and evolution of the azonal wetland vegetation in the south-eastern part of the Baltic region during the Holocene.
Macrofossil
Mire
Cite
Citations (1)
Lateglacial and early Holocene macrofossils of Norway spruce (Picea abies) found in the Swedish Scandes have challenged the prevailing theory, based on pollen analyses, that spruce arrived rather late ( c. 3500 yr cal. BP) to Sweden. The aim of this study was to investigate whether the early-Holocene spruce establishment could be effectively assessed by pollen analysis. Four pollen analyses were carried out on peat mires in a river valley in the southern Swedish Scandes, where spruce has been present since the lateglacial. One site was analysed for the occurrence of macrofossil wood remains. The pollen diagrams display the local vegetation history for the last c., 10 000 years, and reveal the first occurrence of spruce pollen c. 9000 yr cal. BP. Spruce apparently became established in the northern part of the valley around 9000 BP, and thereafter spread south wards. The results are discussed in terms of the background pollen signal for spruce, i.e., local versus regional pollen, the presence or absence of forest on the sites during the Holocene, and the selection of study sites in relation to the aim of the investigation. Pollen analysis, as applied in this study, is shown to be a relevant method for the study of tree immigration in the early Holocene, at both a local and a landscape level.
Macrofossil
Cite
Citations (64)
Macrofossil
Cite
Citations (0)
Holocene summer temperature reconstructions from northern Europe based on sedimentary pollen records suggest an onset of peak summer warmth around 9,000 years ago. However, pollen-based temperature reconstructions are largely driven by changes in the proportions of tree taxa, and thus the early-Holocene warming signal may be delayed due to the geographical disequilibrium between climate and tree populations. Here we show that quantitative summer-temperature estimates in northern Europe based on macrofossils of aquatic plants are in many cases ca. 2 °C warmer in the early Holocene (11,700-7,500 years ago) than reconstructions based on pollen data. When the lag in potential tree establishment becomes imperceptible in the mid-Holocene (7,500 years ago), the reconstructed temperatures converge at all study sites. We demonstrate that aquatic plant macrofossil records can provide additional and informative insights into early-Holocene temperature evolution in northernmost Europe and suggest further validation of early post-glacial climate development based on multi-proxy data syntheses.
Macrofossil
Holocene climatic optimum
Proxy (statistics)
Cite
Citations (94)
Macrofossil
Ombrotrophic
Sphagnum
Testate amoebae
Cite
Citations (34)