Browsing by Author "Olley, JM"
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- ItemAnomalous tree-ring identification facilitated by AMS 14C analysis in subtropical and tropical Australian Araucariaceae samples enables development of a long-term, high-resolution climate reconstruction(Australian Nuclear Science and Technology Organisation, 2021-11-17) Haines, HA; Palmer, JG; Hua, Q; English, NB; Hiscock, W; Turney, CSM; Marjo, CE; Gadd, PS; Kemp, J; Olley, JMIn Australia the majority of tropical and subtropical regions lack long-term instrumental climate records. Paleoclimate reconstructions from tree rings provide one alternative but very few dendrochronological investigations have so far been undertaken. Early assessments of mainland Australian tree species were discouraging due to the high prevalence of anomalous ring boundaries. Some species, however, were seen as more favourable than others including those in the Araucariaceae family which is common along the subtropical-tropical Australian east coast. These trees are longer lived than many other species in the region and contain growth rings known to be annual in nature and responsive to climatic conditions. There is however, a heavy prevalence of anomalous ring boundaries in species from this family which must be accounted for when dating these species. Here we describe the tree-ring characteristics and growth response from two stands of Hoop pine (Araucaria cunninghamii) trees located in subtropical and tropical Queensland, Australia (regions known for experiencing extreme hydroclimatic events). Confirmation of annual growth driven by moisture sensitivity was determined using radius dendrometers on four trees in Lamington National Park (c. 28º S). Tree cores were collected from both the Lamington stand as well as a stand at Hidden Valley near Paluma, Queensland (c. 19º S). Ring-width assessment showed the presence of false, faint, locally absent, and wedging rings in both sites. Results of bomb-pulse radiocarbon dating of selected single tree rings demonstrated that trees from this species can fall into one of three categories: A – those with locally-absent rings around the circumference of the trees, B – those where false rings were observed, and C – those with many wedging and locally-absent rings. Only trees in the first two categories were able to be included in the master chronologies. Traditional dendrochronological analysis with age validation by bomb-pulse radiocarbon dating allowed for a robust ring-width chronology from 1805-2014 CE to be developed for the Lamington National Park site. Growth-climate analysis of the master tree-ring chronology determined that the strongest environmental correlation was to wet season drought conditions. The strength of this response was compared to local and regional drought indices as well as to a long-term drought reconstruction. The combined analysis led to the development of a 200-year drought reconstruction for the region which shows influences from both the El Niño Southern Oscillation and the Interdecadal Pacific Oscillation. © The Authors
- ItemDeveloping tree-ring chronologies and climate reconstructions from moisture sensitive Araucariaceae trees in tropical and subtropical Australia(Australasian Quaternary Association Inc., 2018-12-10) Haines, HA; English, NB; Hua, Q; Olley, JM; Gadd, PS; Palmer, JG; Kemp, JMany parts of tropical and subtropical Australia lack both annually-resolved long-term instrumental climate data and proxy climate records. This limits our understanding of past climate patterns and impacts. There are however, remnant forest stands where dendroclimatology could be applied to extend the climate record. Tree species in these regions are known to be compromised by numerous ring anomalies and as such are understudied resulting in indistinct tree growth-climate relationships. Recent research of trees in the Araucariaceae family has attempted to address these issues with the goal being to develop long-term climate reconstructions across tropical and subtropical Australia. Araucariaceae trees are commonly found across northern and eastern Australia and are longer lived than many other local non-temperate species. They are known to produce growth rings that are mostly annual and their growth appears sensitive to climate, specifically to moisture conditions. Three Araucariaceae species, hoop pine (Araucaria cunninghamii), bunya pine (Araucaria bidwillii) and purple kauri pine (Agathis atropurpurea) have been studied at five locations within the rainforests of eastern Queensland. Ring anomalies including false, faint, locally absent, and pinching or wedging rings, were identified. This was done by applying bomb-pulse radiocarbon dating and Itrax radiographic analysis to hoop pine trees from subtropical Lamington and D’Aguilar National Parks respectively. Additionally, dendrometers were installed on trees of all three species so that the climate variables influencing seasonal growth could be identified. It was found that moisture conditions drive annual growth in Araucariaceae trees but that the onset and cessation of the growth season is dependent on temperature. Forest elevation also needs to be considered as the growth season length is longer at lower elevation and there is an influence of cloud cover seen in the north Queensland rainforest, which is close to a cloud forest classification. Annual growth was confirmed for all species through this analysis and the suitability for their use in climate reconstruction proven. Following this, a 164-year drought reconstruction for Southeast Queensland was developed using hoop pine trees from the subtropical rainforest of Lamington National Park. Additional work is continuing to further develop a network of long-term Queensland tree-ring climate records. © The Authors
- ItemIdentifying flood and drought events using a 500-year reconstruction of rainfall in the Australian subtropics as determined from hoop pine (Araucaria cunninghamii) tree rings(Science Council of Japan, Japan Association for Quaternary Research, and International Union for Quaternary Research, 2015-07-01) Haines, HA; English, NB; Olley, JM; Hua, Q; Heijnis, H; Palmer, JGSubtropical Australia is highly susceptible to extreme events like the catastrophic floods that occurred in Southeast Queensland (SEQ) in 2011. This event was suggested to be a 1 in 1000 year flood, however, preliminary research of past flood deposits has indicated that a similar sized event occurred about 200 years ago. Our understanding of the past frequency of these types of events is limited because there are few long-term climate records available for this region. Historical precipitation records extend back to the 19th century, which is not of a sufficient duration to understand extreme event frequencies. Other annual proxy methods of rainfall reconstruction are needed to better understand the flood and drought history of this area. Tree rings provide an annual record of past conditions based on a single environmental variable that is limiting tree growth. Here we present the first long-term (>150 years) Australian subtropical tree ring reconstruction of rainfall from Lamington National Park, a natural area of rainforest on the southern boundary of SEQ. Hoop Pine (Araucaria cunninghamii) trees were used as they are one of the longest lived tree species in subtropical Australia, they grow in response to precipitation conditions, and they put on a visible annual ring that can be measured. This record was developed using a multi-technique approach where traditional ring width measuring, X-ray densitrometry, and radiocarbon dating were combined to create a robust chronology that was then used to reconstruct rainfall. Years with major rainfall events are confirmed through Calcium and Strontium signals identified in the tree rings using ITRAX XRF trace elements. Climate conditions for years with known flood and drought events were then compared to our reconstruction to identify potential extreme events in SEQ beyond the period of instrumental record. The methodology, results, and future directions of this research will be discussed.
- ItemA new method for dating tree-rings in trees with faint, indeterminate ring boundaries using the Itrax core scanner(Elsevier, 2018-05-15) Haines, HA; Gadd, PS; Palmer, JG; Olley, JM; Hua, Q; Heijnis, HEastern Australia is known to experience multi-decadal periods of flood and drought. Subtropical Southeast Queensland is one region where these devastating extreme events occur regularly yet a full understanding of their frequency and magnitude cannot be determined from the short duration (<100 years) climate data available for the region. Tree-rings are a potential source of long-term (>100 years) proxy rainfall information but locating suitable forest stands is difficult due to extensive land clearing by European settlers. Another factor deterring the use of trees as proxy data sources is that longer-lived species frequently contain anomalous rings, particularly faint rings, hindering their use for paleoclimate study. Here we present a method which overcomes the problems of identifying faint ring boundaries in trees by using X-radiographs and density patterns developed on the Itrax core scanner. We analysed 39 tree cores from 20 trees at a site in D'Aguilar National Park located just north of Brisbane city in Queensland, Australia. Each core had a 2 mm lath cut perpendicular to its rings which was then passed through an Itrax core scanner. The tree-ring boundaries were identified on the image by both the visual features in the radiograph and the change in density observed between rings. From this information we developed a tree-ring chronology. The chronology was checked using bomb-pulse radiocarbon dating on five trees to confirm the annual nature of the rings, and to correct dating errors in the chronology due to false rings which are common in this species. Climate response function analysis showed Austral annual rainfall (June–May) was the dominant environmental variable driving tree growth. Finally, a 69-year statistically significant reconstruction of Brisbane precipitation was produced showing that this non-destructive Itrax ring identification technique together with age validation by bomb-pulse radiocarbon dating is useful for dendroclimatological studies of trees with faint ring boundaries. Crown Copyright © 2018 Published by Elsevier B.V
- ItemThe use of multiple dendrochronological techniques to develop a 200-year drought record for subtropical Southeast Queensland, Australia(European Geosciences Union (EGU), 2020-05-04) Haines, HA; Palmer, JG; English, NB; Hua, Q; Gadd, PS; Kemp, J; Olley, JMIn 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. Toona ciliata). One exception noted in the early species assessment suggested that trees in the Araucariaceae 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. Here we describe the results from a stand of Araucaria cunninghamii 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 Niño Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.