102 research outputs found
sj-docx-1-hol-10.1177_09596836241236340 – Supplemental material for The history of Fagus sylvatica at its northern limit in Vendsyssel, Denmark
No full textSupplemental material, sj-docx-1-hol-10.1177_09596836241236340 for The history of Fagus sylvatica at its northern limit in Vendsyssel, Denmark by Gina E Hannon, Richard HW Bradshaw, Richard C Chiverrell and Jens Peter Skovsgaard in The Holocene</p
A high-resolution pollen and geochemical analysis of late Holocene human impact and vegetation history in southern Cumbria, England.
No full textThe historic era, which in Cumbria begins with the Roman invasion of AD 71, is a frequently neglected period in palaeoecological research, but its study can bring benefits in improving knowledge of landscape history and in understanding the significance and limitations of palaeoecological records. Pollen and geochemical data are presented for late Holocene records from Deer Dyke and Hulleter Mosses in southern Cumbria. The records show initially low levels of anthropogenic impact, followed by a phase of forest clearance and mixed agriculture from the 7th to 11th centuries AD. The timing of these clearances suggests that they were initially Anglo-Saxon in origin, rather than Norse. Further clearances in the 16th century AD are interpreted as a response to monastic dissolution and late Tudor population pressures; the landscapes reached their contemporary form following extensive clearances in the 17th century AD. Silicon and titanium concentrations at Deer Dyke Moss were used to reconstruct past levels of atmospheric dust loading, which is broadly related to soil erosion. Geochemical influx was found to peak during periods of landscape transition rather than from established land use. This relationship with pollen data is thought to reflect the predominantly low levels of anthropogenic impact in the region, which changes as substantial woodland clearances during the 16th century AD and continuous land use pressure since then have greatly increased the supply of airborne dust
Holocene environmental reconstruction of sediment-source linkages at Crummock Water, English Lake District, based on magnetic measurements
No full textTo reconstruct Lateglacial and Holocene environmental changes in the British uplands, two c. 5.8 m long sediment cores from Crummock Water (NW England), together with several hundred soil samples from the Crummock Water catchment, were studied using magnetic techniques. Optically stimulated luminescence (OSL) dating using fine silt quartz and 14C dating of terrestrial plant macrofossils were used to establish a chronology for the lake sediments. A good agreement between optical and 14C ages indicates first, that the OSL dating method can be used to date lake sediments in the British Isles; second that macrofossil-based 14C dating can be used to avoid the problem of 'old carbon' error associated with bulk sample 14C dating of lake sediments and third, that the established chronology is robust. The lake sediment magnetic properties indicate a series of changes in sediment composition during the Holocene, which correlate well with sediment lithology, water content and weight-loss-on-ignition. The first change corresponds to the Lateglacial/Postglacial climatic shift at around 11400 years ago; the subsequent suite of changes corresponds to a probable regional onset of human activity at 2000 BC, and particularly to the intensification of human activity at around AD 900. A comparison of the lake sediment magnetic properties and those of the catchment soils shows a clear linkage for the Lateglacial period, and for the period after AD 900. In contrast, detailed magnetic measurements of the early- through mid-Holocene sediments suggest that their magnetic properties are dominated by bacterial magnetosomes
Experimental evidence for sustained carbon sequestration in fire-managed peat moorlands
No full textThis dataset contains the raw data for the paper "Experimental evidence for sustained carbon sequestration in fire-managed peat moorlands" by R. H. Marrs, E-L Marsland, R. Lingard, P. G. Appleby, G. T. Piliposyan, R. J. Rose, J. O’Reilly, G. Milligan, K. A. Allen, J.G. Alday, V. Santana, H. Lee, K. Halsall, and R.C. Chiverrell. The paper is to be published in Nature Geoscience in 2018.
The study measures peat and C accumulation in peat cores taken from the long-term burning experiment at Moor House NNR. Moor House is an UK Environmental Change Network Site. The accumulation rates were based on measuring the Pb content through the peat profiles and referencing them to master cores, which were dated radiometrically. The experimental design is described in the README file.
Two datasets are provided:
#1.Accumulation rates: contains the peat and C accumulation rates for two time periods: recent (1963.2016) and pre-experiment (1876.1963).
#2.NIRS vs L-o-I data: contains the estimated C concentrations in peat samples estimated by Near Infra-Red Spectroscopy (NIRS) and loss-on-ignition
Erratum: Human settlement of East Polynesia earlier, incremental, and coincident with prolonged South Pacific drought (Proceedings of the National Academy of Sciences of the United States of America(2020)117(8813-8819)DOI: 10.1073/pnas.1920975117)
No full textCorrection for "Human settlement of East Polynesia earlier, incremental, and coincident with prolonged South Pacific drought," byDavid A. Sear,Melinda S. Allen, JonathanD. Hassall, Ashley E. Maloney, Peter G. Langdon, Alex E. Morrison, Andrew C. G. Henderson, Helen Mackay, Ian W. Croudace, Charlotte Clarke, Julian P. Sachs, Georgiana Macdonald, Richard C. Chiverrell, Melanie J. Leng, L. M. Cisneros-Dozal, and Thierry Fonville, which was first published April 6, 2020; 10.1073/pnas.1920975117 (Proc. Natl. Acad. Sci. U.S.A. 117, 8813-8819). The authors note that Emma Pearson should be added to the author list after Thierry Fonville. Emma Pearson should be credited with performing research and analyzing data. The corrected author line, affiliation line, and author contributions appear below. The author line, affiliations, and contributions sections have been corrected online. The authors note that the following statement should be added to the Acknowledgments: "E.P. acknowledges NERC grant BRIS/ 81/0415"
Complex spatial feedbacks of tephra redistribution, ice melt and surface roughness modulate ablation on tephra covered glaciers
No full textTephra fallout from the 2011 Grímsvötn eruption onto Svínafellsjökull, Iceland, created an ice-ash landscape of a type that is rarely studied but is nevertheless common in glaciovolcanic regions. We used terrestrial laser scanning (TLS) to measure ice surface topography and absorption at high spatial resolution, confirming ablation rates either reduce or increase under thick (insulating) and thin (reduced albedo) ash deposits, respectively. Fourier transform analysis of the TLS data identified that a three-fold increase in aerodynamic roughness was attributable to an increase in larger (>0.2m) surface features. Moreover, TLS measurements revealed the importance of ash redistribution by meltwater in generating differential melting which modifies roughness and ash patchiness, such that the net effect of these spatial ash-ice feedbacks was to reduce ablation rates by up to 59%. The modulating effects of these previously undocumented feedbacks on ablation rates are, therefore, significant and must be correctly parameterized if ashcovered glacier mass balances are to be predicted correctly
Correction for Sear et al., Human settlement of East Polynesia earlier, incremental, and coincident with prolonged South Pacific drought.
No full textCorrection for "Human settlement of East Polynesia earlier, incremental, and coincident with prolonged South Pacific drought," byDavid A. Sear,Melinda S. Allen, JonathanD. Hassall, Ashley E. Maloney, Peter G. Langdon, Alex E. Morrison, Andrew C. G. Henderson, Helen Mackay, Ian W. Croudace, Charlotte Clarke, Julian P. Sachs, Georgiana Macdonald, Richard C. Chiverrell, Melanie J. Leng, L. M. Cisneros-Dozal, and Thierry Fonville, which was first published April 6, 2020; 10.1073/pnas.1920975117 (Proc. Natl. Acad. Sci. U.S.A. 117, 8813-8819). The authors note that Emma Pearson should be added to the author list after Thierry Fonville. Emma Pearson should be credited with performing research and analyzing data. The corrected author line, affiliation line, and author contributions appear below. The author line, affiliations, and contributions sections have been corrected online. The authors note that the following statement should be added to the Acknowledgments: "E.P. acknowledges NERC grant BRIS/ 81/0415"
Reply to comment: Cumulative probability functions and their role in evaluating the chronology of geomorphological events during the Holocene. Richard C. Chiverrell, Varyl, R. Thorndycraft And Thomas, O. Hoffmann, Journal of Quaternary Science 26: 76-85
No full text
Estimating aerodynamic roughness over complex surface terrain
No full textSurface roughness plays a key role in determining aerodynamic roughness length (zo) and shear velocity, both of which are fundamental for determining wind erosion threshold and potential. Whilst zo can be quantified from wind measurements, large proportions of wind erosion prone surfaces remain too remote for this to be a viable approach. Alternative approaches therefore seek to relate zo to morphological roughness metrics. However, dust emitting landscapes typically consist of complex small-scale surface roughness patterns and few metrics exist for these surfaces which can be used to predict zo for modelling wind erosion potential. In this study terrestrial laser scanning was used to characterise the roughness of typical dust emitting surfaces (playa and sandar) where element protrusion heights ranged from 1 to 199?mm, over which vertical wind velocity profiles were collected to enable estimation of zo. Our data suggest that, although a reasonable relationship (R^2?>?0.79) is apparent between 3D roughness density and zo, the spacing of morphological elements is far less powerful in explaining variations in zo than metrics based on surface roughness height (R^2?>?0.92). This finding is in juxtaposition to wind erosion models that assume the spacing of larger-scale isolated roughness elements is most important in determining zo. Rather, our data show that any metric based on element protrusion height has a higher likelihood of successfully predicting zo. This finding has important implications for the development of wind erosion and dust emission models that seek to predict the efficiency of aeolian processes in remote terrestrial and planetary environment
- …
