Maximum latewood density records of Great Basin Bristlecone pine (Pinus Longaeva) from the White Mountains, California

<p>Great Basin Bristlecone pine (Pinus longaeva) is known for its longevity. The longest continuous tree-ring width chronology covers more than 9000 years. Tree-ring width of upper treeline bristlecone pine trees is influenced by summer temperature variability at decadal to centennial scales, but to infer a temperature signal on interannual scales, Maximum Latewood Density (MXD) is a better proxy. Here, we present a preliminary MXD chronology to investigate the temperature signal in upper treeline and lower elevation bristlecone pines. MXD was measured with an X-ray Computed Tomography toolchain in 24 dated cores,  with the oldest sample dating back to 776 CE. Ring and fibre angles were corrected and two MXD chronologies for different elevations were developed, which will be used to study climate-growth relationships and the effect of elevation on them. Future scanning will allow constructing a 5000+ year-long MXD chronology from upper treeline sites, which will provide an annual-resolution North American temperature record covering the mid-to-late Holocene.</p>

Annual Variation in Atmospheric 14C Between 1700 BC and 1480 BC

ABSTRACTIn 2018 Pearson et al. published a new sequence of annual radiocarbon (14C) data derived from oak (Quercus sp.) trees from Northern Ireland and bristlecone pine (Pinus longaeva) from North America across the period 1700–1500 BC. The study indicated that the more highly resolved shape of an annually based calibration dataset could improve the accuracy of 14C calibration during this period. This finding had implications for the controversial dating of the eruption of Thera in the Eastern Mediterranean. To test for interlaboratory variation and improve the robustness of the annual dataset for calibration purposes, we have generated a replicate sequence from the same Irish oaks at ETH Zürich. These data are compatible with the Irish oak 14C dataset previously produced at the University of Arizona and are used (along with additional data) to examine inter-tree and interlaboratory variation in multiyear annual 14C time-series. The results raise questions about regional 14C offsets at different scales and demonstrate the potential of annually resolved 14C for refining subdecadal and larger scale features for calibration, solar reconstruction, and multiproxy synchronization.

Maximum latewood density records of the oldest trees in the world: Great Basin Bristlecone pine (Pinus Longaeva)

<p>Great Basin Bristlecone pine (Pinus longaeva) is known for its trees that attain old age. The longest chronology is more than 9000 years long, and the temperature-sensitive upper treeline chronology extends back to 5000 years. The ring width pattern of upper treeline bristlecone pine trees are strongly influenced by temperature variability at decadal to centennial scales. To infer a climate signal on annual scales, MXD is shown to be a better temperature proxy. Here, we present a preliminary Maximum Latewood Density (MXD) chronology of bristlecone pine to investigate the temperature signal in upper treeline and below. Maximum latewood density (MXD) from 24 dated cores (from various sites ranging from the upper treeline and below, oldest sample dates back to 776 AD) was determined with an X-ray CT toolchain. Ring and fibre angles were corrected and a MXD chronology was constructed. The resulting MXD chronology will be correlated to summer temperature. Future scanning will allow constructing a + 5000 year MXD chronology and could reveal the cooling effect of volcanic eruptions through this period.</p>

Pinus aristata, P. balfouriana und P. longaeva, drei bemerkenswerte Kiefernarten aus dem Südwesten der USA

Pinus aristata, Pinus balfouriana und Pinus longaeva sind drei ähnliche Kiefernarten. Sie sind im Westen der USA heimisch und können mit über 1000 Jahren sehr alt werden. Wichtige Unterscheidungsmerkmale beziehen sich auf die Nadeln. Eigene Untersuchungen zeigen, dass aber die Zahl der Harzkanäle pro Nadel kein bestimmungsrelevantes Merkmal ist, obwohl dies in der Literatur oft angegeben wird. Die drei Kiefernarten werden mit ihrer Biologie, Morphologie und Ökologie vorgestellt.