The Experts below are selected from a list of 6264 Experts worldwide ranked by ideXlab platform

Griggs Carol - One of the best experts on this subject based on the ideXlab platform.

Peder Gjerdrum - One of the best experts on this subject based on the ideXlab platform.

  • estimating missing sapwood rings in three european gymnosperm species by the heartwood age rule
    Dendrochronologia, 2013
    Co-Authors: Peder Gjerdrum
    Abstract:

    Abstract Precise dating of the year of felling is one intended outcome of Dendrochronology. However, occasionally some or all sapwood rings might be missing, either due to deterioration or because they were carved off, or for some other reason. Consequently, while heartwood is preserved, sapwood might be fully or partially missing. In such cases, the year of felling must be estimated by adding a suitable number of sapwood rings. A heartwood age rule (HAR) has been advocated for Scots pine and adapted to European larch and Cembra pine, implying a linear relationship between sapwood ring count and the square root of heartwood ring count, largely irrespective of position in the stem. The same rule applied to all observations of a species, irrespective of silviculture, location or fertility of the growth site. Scots pine had twice or thrice as many sapwood rings as Cembra pine, which had 10% more rings than larch. The magnitude of model residuals was proportional to estimated sapwood ring count. Relative residuals were roughly normally distributed. To be applicable in Bayesian modelling in Dendrochronology analyses, detailed information on model errors has been provided.

  • estimating missing sapwood rings in three european gymnosperm species by the heartwood age rule
    Dendrochronologia, 2013
    Co-Authors: Peder Gjerdrum
    Abstract:

    Abstract Precise dating of the year of felling is one intended outcome of Dendrochronology. However, occasionally some or all sapwood rings might be missing, either due to deterioration or because they were carved off, or for some other reason. Consequently, while heartwood is preserved, sapwood might be fully or partially missing. In such cases, the year of felling must be estimated by adding a suitable number of sapwood rings. A heartwood age rule (HAR) has been advocated for Scots pine and adapted to European larch and Cembra pine, implying a linear relationship between sapwood ring count and the square root of heartwood ring count, largely irrespective of position in the stem. The same rule applied to all observations of a species, irrespective of silviculture, location or fertility of the growth site. Scots pine had twice or thrice as many sapwood rings as Cembra pine, which had 10% more rings than larch. The magnitude of model residuals was proportional to estimated sapwood ring count. Relative residuals were roughly normally distributed. To be applicable in Bayesian modelling in Dendrochronology analyses, detailed information on model errors has been provided.

Johannes Koch - One of the best experts on this subject based on the ideXlab platform.

  • improving age estimates for late holocene glacial landforms using Dendrochronology some examples from garibaldi provincial park british columbia
    Quaternary Geochronology, 2009
    Co-Authors: Johannes Koch
    Abstract:

    Abstract Dating of late Holocene landforms below treeline in high mountains is commonly done using Dendrochronology. Four factors can reduce the accuracy of ages obtained by Dendrochronology: (1) locating the oldest living tree on a surface; (2) the method of counting the rings; (3) the age-height correction factor; and (4) ecesis, which is the time it takes trees to successfully germinate on a bare surface. A review of published studies from the western Cordillera of the Americas shows that some of these issues have not been fully addressed. Research in Garibaldi Provincial Park in the southern Coast Mountains of British Columbia shows that the accuracy of tree-ring ages can be improved if (1) crossdating and chronology construction, rather than simple ring counts, are done; (2) individual age-height correction factors are applied; and (3) site-specific ecesis estimates are made. While these suggestions are not always necessary to their fullest extent, researchers should at least report their methods in more detail and provide uncertainties in their age estimates that take into account age-height and ecesis corrections.

Richard G Everett - One of the best experts on this subject based on the ideXlab platform.

  • Dendrochronology based fire history of mixed conifer forests in the san jacinto mountains california
    Forest Ecology and Management, 2008
    Co-Authors: Richard G Everett
    Abstract:

    Abstract The growing public awareness of the increasing number of large wildfires across forested landscapes, coupled with needs of resource base management has accelerated research into forest reference conditions and the historical role of fire in coniferous ecosystems. This work investigates historical fire regimes of mixed-conifer forests in the San Jacinto Mountains of southern California using fire-scar Dendrochronology. As such this is the first reconstruction of fire history in the mixed-conifer forests of southern California using landscape-scale systematic-based fire-scar Dendrochronology. The pre-historical fire size, seasonality, and frequency within these forests are reconstructed and demonstrated graphically, employing systematic sampling and Geographical Information System (GIS) reconstruction. A 250 m grid system was overlaid upon a 270 ha sample location, and fire-scar samples were collected from each of the grid intersection points. Fire-scar Dendrochronology resulted in a 653 years long chronology, indicating a point mean fire return interval of 5.2 years, and an area wide grand mean fire interval of 32.2 years. The majority of fires occurred within latewood or at the ring boundary. Graphic modelling of fire events indicate three-quarters of all fires sampled were less than 6.25 ha in size, but burned over 50% of the area sampled during the period; only a small portion of fires were larger than 18 ha within the sample area. Use of systematic sampling is an important step in modeling long-term frequency and effects of fire on a landscape level, and is invaluable to the long-term management planning.

Batenburg K.j. - One of the best experts on this subject based on the ideXlab platform.

  • A novel method for Dendrochronology of large historical wooden objects using line trajectory X-ray tomography
    'Springer Science and Business Media LLC', 2021
    Co-Authors: Bossema F.g., Domínguez-delmás M., Palenstijn, W.j. Jan), Kostenko A., Dorscheid J., Coban S.b., Hermens E., Batenburg K.j.
    Abstract:

    Dendrochronology is an essential tool to determine the date and provenance of wood from historical art objects. As standard methods to access the tree rings are invasive, X-ray computed tomography (CT) has been proposed for non-invasive dendrochronological investigation. While traditional CT can provide clear images of the inner structure of wooden objects, it requires their full rotation, imposing strong limitations on the size of the object. These limitations have previously encouraged investigations into alternative acquisition trajectories, including trajectories with only linear movement. In this paper, we use such a line-trajectory (LT) X-ray tomography technique to retrieve tree-ring patterns from large wooden objects. We demonstrate that by moving a wooden artifact sideways between the static X-ray source and the detector during acquisition, sharp reconstruction images of the tree rings can be produced. We validate this technique using computer simulations and two wooden test planks, and demonstrate it on a large iconic chest from the Rijksmuseum collection (Amsterdam, The Netherlands). The LT scanning method can be easily implemented in standard X-ray imaging units available at museum research facilities. Therefore, this scanning technique represents a major step towards the standard implementation of non-invasive Dendrochronology on large wooden cultural heritage objects

  • Line trajectory X-ray tomography for Dendrochronology of large wooden objects
    2020
    Co-Authors: Bossema F.g., Domínguez-delmás M., Hermens E., Liere R. Van, Batenburg K.j.
    Abstract:

    Abstract. Computational Tomography (CT) is a powerful non-invasive 3D imaging technique for cultural heritage research, as the interior of art-historical objects can be investigated by virtually slicing through the object. An application is Dendrochronology (i.e. tree-ring research), in which wooden objects are dated by measuring their tree rings and comparing this series with reference chronologies anchored in time. The more tree rings in a series, the higher the chances to obtain a date. Tree rings are not always accessible for measuring on the transverse surface of art-historical objects such as panel paintings and sculptures. In these cases, CT imaging can provide access to the internal tree rings patterns. Most art-historical wooden objects are too large to fit or fully rotate in a medical or lab-based CT scanner. However, for dendrochronological research only one (virtual) cut through the wood is needed, not a full 3D reconstruction. Here we propose a novel line trajectory scan, in which the object is moved sideways between source and detector and very limited angle data is collected. By choosing the orientation of the tree rings approximately parallel to the source-detector axis, they can be visualised sharply in one slice using an iterative reconstruction method. We will demonstrate both the data collection method and the associated algorithms for tomography-based Dendrochronology of large wooden objects with the line trajectory scan