The iconic Plaza Tree of Pueblo Bonito is widely believed to have been a majestic pine standing in the west courtyard of the monumental great house during the peak of the Chaco Phenomenon (AD 850–1140). The ponderosa pine ( Pinus ponderosa ) log was discovered in 1924, and since then, it has been included in “birth” and “life” narratives of Pueblo Bonito, although these ideas have not been rigorously tested. We evaluate three potential growth origins of the tree (JPB-99): Pueblo Bonito, Chaco Canyon, or a distant mountain range. Based on converging lines of evidence—documentary records, strontium isotopes ( 87 Sr/ 86 Sr), and tree-ring provenance testing—we present a new origin for the Plaza Tree. It did not grow in Pueblo Bonito or even nearby in Chaco Canyon. Rather, JPB-99 originated from the Chuska Mountains, over 50 km west of Chaco Canyon. The tree was likely carried to Pueblo Bonito sometime between AD 1100 and 1130, although why it was left in the west courtyard, what it meant, and how it might have been used remain mysteries. The origin of the Plaza Tree of Pueblo Bonito underscores deep cultural and material ties between the Chaco Canyon great houses and the Chuska landscape.
ABSTRACT Our understanding of land‐based cool season temperature variability over the past millennium is limited by the relative lack of annually resolved temperature proxies, especially in the Southern Hemisphere. Here, we develop the first earlywood (EW) and latewood (LW) width chronologies from Australia based on the Tasmanian endemic conifer Athrotaxis s elaginoides in the far southeast of Australia. We also develop total ring width (RW), EW and LW chronologies from a new site in the far south. We compare the climate responses of RW, EW and adjusted LW chronologies of three A. selagnoides sites near the southern extent of the species with three sites of the species near the northern extent of the species. RW and EW at the southern sites are strongly and positively related to cool season temperature (July–October), but in the north, RW and EW are more strongly and positively related with summer (December–February) temperatures. Once adjusted for the influence of the same growing season EW, LW in the north is very strongly negatively correlated with January–February temperatures across southeastern Australia. The new southern RW and EW chronologies can be used to extend one of only two annually resolved regional cool season temperature reconstructions in the Southern Hemisphere back a further 180 years.
For Australia, there are only a few east coast low (ECL) databases that have been generated to explore aspects of ECL development, movement and subsequent impacts. Improved databases that include ECL track data will enhance future forecasting and damage mitigation on the east coast of Australia. This paper compares ECL track characteristics of a new low-pressure dataset, NCEP1 (1950–2019), to the recently updated MATCHES (Maps and Tables of Climate Hazards of the Eastern Seaboard) database (1950–2019) in order to identify similarities and differences of track characteristics that may be important for future ECL research. To achieve this, defining parameters such as intensity – used to make the MATCHES database – were applied to NCEP1 to ensure a direct comparison of historical ECL events. Although both databases display similar patterns in ECL seasonality and track characteristics, we show that the NCEP1 database identifies additional events not captured in MATCHES and provides improved track morphology of certain well-known historical events (such as the 2007 Pasha Bulker storm and the 1998 Sydney to Hobart Yacht Race). Importantly, this research builds upon Australian ECL research and notes an improvement on the MATCHES database, with NCEP1 offering an almost two-fold outperformance in storm tracking (track length and duration) and greater spatial coverage outside the traditional ECL box.
<p>In Australia the majority of tropical and subtropical regions lack any long-term (multi-decadal to centennial scale) instrumental climate records highlighting a need for alternatives such as proxy climate reconstructions. Despite this need, only a limited number of terrestrial proxy sources are available. Tree-rings provide one of the few options for climate reconstructions yet very little dendrochronological investigation has been undertaken as early assessments of tropical Australian species in the 1970s and 1980s indicated most species had short life-spans, poorly preserved timbers, or were compromised by having many ring anomalies. There has also been limited effort into understanding the growth-climate relationships of these trees with only a few studies undertaken targeting specific species that have unfortunately been heavily cleared from the region (eg. <em>Toona ciliata</em>). One exception noted in the early species assessment suggested that trees in the <em>Araucariaceae</em> family, a common tree family along the tropical Australian east coast, is longer lived than many other species in the region, contains growth rings which are annual in nature, and grows in response to climatic conditions.</p><p>Here we describe the results from a stand of <em>Araucaria cunninghamii</em> trees located in Lamington National Park, a World Heritage listed rainforest in subtropical Southeast Queensland, Australia (a region known for experiencing extreme hydroclimatic events). Our assessment discovered the presence of false, faint, locally absent, and pinching rings. By combining traditional dendrochronological analysis (eg. crossdating) with more recent techniques such as age validation by bomb-pulse radiocarbon dating and tree-ring density analysis, a robust ring-width chronology from 1805-2014 was developed. Dendrometers installed on four trees at the Lamington site confirmed that tree growth was annual and that moisture sensitivity was driving growth. Further growth-climate analysis indicated that the strongest correlation to the tree-ring chronology was specifically related to drought conditions in the region. The strength of this response was compared to both local and regional spatial areas and to drought indices such as the self-calibrating Palmer Drought Severity Index (scPDSI), the Standardized Precipitation Evaporation Index (SPEI), and the long-term drought conditions shown by the Australian and New Zealand Drought Atlas (ANZDA). The combined analysis led to the development of a 200-year drought reconstruction for the region and demonstrates influences from both the El Ni&#241;o Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO).</p>
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