Castanea sativa is classified as non-indigenous in Britain and Ireland. It was long held that it was first introduced into Britain by the Romans, until a recent study found no corroborative evidence ...of its growing here before c. AD 650. This paper presents new data on the genetic diversity of C. sativa in Britain and Ireland and potential ancestral sources in continental Europe. Microsatellite markers and analytical methods tested in previous European studies were used to genotype over 600 C. sativa trees and coppice stools, sampled from ancient semi-natural woodlands, secondary woodlands and historic cultural sites across Britain and Ireland. A single overall genepool with a diverse admixture of genotypes was found, containing two sub groups differentiating Wales from Ireland, with discrete geographical and typological clusters. C. sativa genotypes in Britain and Ireland were found to relate predominantly to some sites in Portugal, Spain, France, Italy and Romania, but not to Greece, Turkey or eastern parts of Europe. C. sativa has come to Britain and Ireland from these western European areas, which had acted as refugia in the Last Glacial Maximum; we compare its introduction with the colonization/translocation of oak, ash, beech and hazel into Britain and Ireland. Clones of C. sativa were identified in Britain, defining for the first time the antiquity of some ancient trees and coppice stools, evincing both natural regeneration and anthropogenic propagation over many centuries and informing the chronology of the species' arrival in Britain. This new evidence on the origins and antiquity of British and Irish C. sativa trees enhances their conservation and economic significance, important in the context of increasing threats from environmental change, pests and pathogens.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Little Ice Age (LIA) is a well-recognised palaeoclimatic phenomenon, although its causes, duration and severity have been matters of debate and dispute. Data from a wide range of archives have ...been used to infer climate variability before, during and after the LIA. Some published proxy-climate data from peatlands imply that two particularly severe episodes within the LIA may be contemporaneous between hemispheres; these echo a previous climatic downturn ca. 2800 cal BP of similar severity but lesser duration. Here, we present palaeoclimate data from the mid- to late-Holocene, reconstructed from three blanket peats in Yorkshire: Mossdale Moor, Oxenhope Moor and West Arkengarthdale. Multiproxy techniques used for palaeoclimatic reconstruction were plant macrofossil, pollen and humification analyses. Dating was provided by a radiocarbon-based chronology, aided by spheroidal carbonaceous particles (SCPs) for all sites, and 210Pb dates for one. The LIA presents as a distinct climatic event within each palaeoenvironmental record at the three sites. These indications are compared with terrestrial datasets from northwest Europe and elsewhere. A broad degree of synchronicity is evident, signifying that the LIA is one of the most pronounced downturns in global climate in the last ca. 6000 years, and arguably the most routinely recorded within the Holocene.
Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists ...of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan Plateau. For all northern peatlands, carbon content in organic matter was estimated at 42 ± 3% (standard deviation) for Sphagnum peat, 51 ± 2% for non-Sphagnum peat, and at 49 ± 2% overall. Dry bulk density averaged 0.12 ± 0.07 g/cm3, organic matter bulk density averaged 0.11 ± 0.05 g/cm3, and total carbon content in peat averaged 47 ± 6%. In general, large differences were found between Sphagnum and non-Sphagnum peat types in terms of peat properties. Time-weighted peat carbon accumulation rates averaged 23 ± 2 (standard error of mean) g C/m2/yr during the Holocene on the basis of 151 peat cores from 127 sites, with the highest rates of carbon accumulation (25–28 g C/m2/yr) recorded during the early Holocene when the climate was warmer than the present. Furthermore, we estimate the northern peatland carbon and nitrogen pools at 436 and 10 gigatons, respectively. The database is publicly available at https://peatlands.lehigh.edu.
We examine mid- to late Holocene centennial-scale climate variability in Ireland using proxy data from peatlands, lakes and a speleothem. A high degree of between-record variability is apparent in ...the proxy data and significant chronological uncertainties are present. However, tephra layers provide a robust tool for correlation and improve the chronological precision of the records. Although we can find no statistically significant coherence in the dataset as a whole, a selection of high-quality peatland water table reconstructions co-vary more than would be expected by chance alone. A locally weighted regression model with bootstrapping can be used to construct a ‘best-estimate’ palaeoclimatic reconstruction from these datasets. Visual comparison and cross-wavelet analysis of peatland water table compilations from Ireland and Northern Britain show that there are some periods of coherence between these records. Some terrestrial palaeoclimatic changes in Ireland appear to coincide with changes in the North Atlantic thermohaline circulation and solar activity. However, these relationships are inconsistent and may be obscured by chronological uncertainties. We conclude by suggesting an agenda for future Holocene climate research in Ireland.
Holocene paleoclimate reconstructions and comparisons largely rely on accurate age-depth modeling. However, uncertainties in chronology, such as those caused by sparse radiocarbon dates, will hamper ...inter-core comparisons and correlations, and might result in misleading “cause and consequence” conclusions. This study aimed to find a solution to increase the comparability and minimize the uncertainty of wetland chronology as much as possible. Sediment cores were recovered and radiocarbon dated from the Lianhuachi wetland located in Southeastern China. Humification degree and loss-on-ignition (LOI) were determined using colorimetric and combustion methods respectively. Our data were compared with previously published datasets obtained in the same wetland. The results show that independent humification profiles from the Lianhuachi wetland displayed high similarities. This high similarity between the humification profiles allowed us to transfer radiocarbon ages from one core to another using sequence slotting correlation. Applying the humification-based chronology refinement method to all sediment cores resulted in an improvement in the correlation coefficients between the same but independently measured proxy sequences from the wetland, which suggests both the inter- and intra-core comparability was improved. Because determining peat humification degree is easy, inexpensive, and time-saving, we suggest that humification can serve as a tool that can be used to correlate different cores and to transfer published radiocarbon ages within the same wetland (peatland) or in a comparable geological setting, to establish a more robust chronology of these comparable cores. The degree of peat humification can thus serve as a relative dating technique to refine the chronology of wetland (including peatland) records.
Sweet chestnut is a tree of great economic (fruit and wood production), ecological, and cultural importance in Europe. A large-scale landscape genetic analysis of natural populations of sweet ...chestnut across Europe is applied to (1) evaluate the geographic patterns of genetic diversity, (2) identify spatial coincidences between genetic discontinuities and geographic barriers, and (3) propose certain chestnut populations as reservoirs of genetic diversity for conservation and breeding programs. Six polymorphic microsatellite markers were used for genotyping 1608 wild trees sampled in 73 European sites. The Geostatistical IDW technique (ArcGIS 9.3) was used to produce maps of genetic diversity parameters (He, Ar, PAr) and a synthetic map of the population membership (Q value) to the different gene pools. Genetic barriers were investigated using BARRIER 2.2 software and their locations were overlaid on a Digital Elevation Model (GTOPO30). The DIVA-GIS software was used to propose priority areas for conservation. High values of genetic diversity (He) and allelic richness (Ar) were observed in the central area of
C. sativa
’s European distribution range. The highest values of private allelic richness (PAr) were found in the eastern area. Three main gene pools and a significant genetic barrier separating the eastern from the central and western populations were identified. Areas with high priority for genetic conservation were indicated in Georgia, eastern Turkey, and Italy. Our results increase knowledge of the biogeographic history of
C. sativa
in Europe, indicate the geographic location of different gene pools, and identify potential priority reservoirs of genetic diversity.
The
n-alkane distributions from total lipid extracts of ten modern
Sphagnum moss species, collected from a suite of ombrotrophic bogs across Europe, were determined using gas chromatography/mass ...spectrometry (GC/MS).
n-Alkane distributions are reported for the first time for
Sphagnum balticum,
S. majus,
S. angustifolium and
S. lindbergii, which are all dominated by C
23 with the exception of
S. lindbergii, which exhibits a bimodal distribution with C
23 and C
31 as the major homologues. The distributions for individual species generally agree with published compositions, confirming the conservative nature of the
n-alkane compositions, which provide a basis for differentiating the
n-C
23 and
n-C
25 dominated species. Investigations of the variation in
n-C
23/
n-C
25 and
n-C
23/
n-C
31 ratios of
Sphagnum species, using the new and published
n-alkane distributions, reveal that
intra-species variation is generally minor. Critically, the distributions and ratios for most species do not vary among the sites studied, suggesting that they are conservative tracers for a given species, despite differences in growth conditions. In contrast,
inter-species variation exists, allowing differentiation of individual
Sphagnum species based on vegetation biomarkers, specifically the C
25
n-alkane in
S. fuscum and the
n-C
23/
n-C
25 ratio. Biomarker stratigraphic analysis of a 150
cm peat core (Kontolanrahka Bog, Finland) reveal shifts in the
n-C
23/
n-C
25 ratio, which track changes in the abundance of
S. fuscum in the macrofossil record. This supports the application of
n-alkane biomarkers in peat archives for tracking past shifts in individual
Sphagnum species abundance. This will be particularly important where fossil plant remains are highly degraded in, or absent from, peat records.
ACC Task Force on Expert Consensus Decision Pathways∗∗ James L. Januzzi, Jr, MD, FACC Luis C. Afonso, MBBS, FACC Brendan Everett, MD, FACC Adrian F. Hernandez, MD, MHS, FACC William Hucker, MD, PhD ...Hani Jneid, MD, FACC Dharam Kumbhani, MD, SM, FACC Joseph Edward Marine, MD, FACC Pamela Bowe Morris, MD, FACC Robert N. Piana, MD, FACC Karol E. Watson, MD, FACC Barbara S. Wiggins, PharmD, AACC∗∗Formerly named ACC Task Force on Clinical Expert Consensus Documents.Table of Contents Preamblee286 Introductione287 1.1.Document Development Process and Methodologye287 1.1.1.Writing Committee Organizatione287 1.1.2.Document Development and Approvale287 2. Nuclear Cardiology Techniquese327 7.4.1.Nuclear Cardiology General Principlese327 7.4.2.Nuclear Cardiology Equipment Quality, Calibration, and Maintenancee327 7.4.3.Nuclear Cardiology Spatial Resolution and Image Detector Dosee328 7.4.4.Procedures and Practices to Minimize Patient Exposuree328 7.4.5.Procedures and Practices to Protect Occupationally Exposed Healthcare Workers in Nuclear Cardiology Facilitiese330 7.4.6.Summary Checklist of Dose-Sparing Practices for Nuclear Cardiologye330 7.5. Need for Quality Assurance and Traininge344 Referencese344 Appendix A Author relationships With Industry and Other Entities (Relevant): 2018 ACC/ASNC/HRS/NASCI/SCAI/SCCT/SNNMI Expert Consensus Document on Optimal Use of Ionizing Radiation in Cardiovascular Imaging: Best Practices for Safety and Effectivenesse348 Appendix B Peer Reviewer Information: 2018 ACC/ASNC/HRS/NASCI/SCAI/SCCT/SNNMI Expert Consensus Document on Optimal Use of Ionizing Radiation in Cardiovascular Imaging: Best Practices for Safety and Effectivenesse350 Appendix C Abbreviationse351 Preamble This document has been developed as an Expert Consensus Document by the American College of Cardiology (ACC) in collaboration with the American Society of Nuclear Cardiology, Heart Rhythm Society, Mended Hearts, North American Society for Cardiovascular Imaging, Society for Cardiovascular Angiography and Interventions, Society for Cardiovascular Computed Tomography, and Society of Nuclear Medicine and Molecular Imaging. Expert Consensus Documents are intended to inform practitioners, payers, and other interested parties of the opinion of ACC and document cosponsors concerning evolving areas of clinical practice and/or technologies that are widely available or new to the practice community.
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