Developing tree-ring chronologies and climate reconstructions from moisture sensitive Araucariaceae trees in tropical and subtropical Australia
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Date
2018-12-10
Journal Title
Journal ISSN
Volume Title
Publisher
Australasian Quaternary Association Inc.
Abstract
Many 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
Description
Keywords
Tree rings, Climates, Climate models, Moisture, Trees, Australia, Tropical regions, Forests, Climatic change, Queensland
Citation
Haines, H. A., English, N. B., Hua, Q., Olley, J. M., Gadd, P. S., Palmer, J. G., & Kemp, J. (2018). Developing tree-ring chronologies and climate reconstructions from moisture sensitive Araucariaceae trees in tropical and subtropical Australia. Paper presented at the AQUA Biennial Conference, Canberra, 10-14 December 2018. (pp. 85). https://aqua.org.au/wp-content/uploads/2019/10/AQUA-2018-Program.pdf