Hot Topics in Ecology

Climate Change: trees under pressure

Climate change causes widespread tree mortality and health declines
Synthesis by Dr Niels Brouwers (1,2), Professor Giles Hardy (1,2), Dr Katinka X. Ruthrof (1,2), Dr George Matusick (1,3), Dr Melanie Zeppel (4); Affiliations: (1) Centre of Excellence for Climate Change, Woodland and Forest Health; (2) Murdoch University; (3) The Nature Conservancy; (4) Macquarie University.
  • Trees are dying in response to gradual changes in climate and extreme climatic events.
  • Not only are dying and dead trees visually disturbing, species dependant on trees for food and shelter are negatively affected, and carbon storage potential of forests is being lost.
  • Climate change will continue into the future, and investigating where, when, and what kind of changes are likely to occur in the landscape through modelling will be an important research challenge and a priority for effective adaptation and mitigation.
Forest dieback caused by an extreme drought and multiple heatwaves in 2010 and early 2011 in the Northern Jarrah Forest region in southwest Western Australia. Photo: George Matusick, May 2011.

Global changes in climate are having a significant impact on forested ecosystems, causing increases in tree mortality rates, and decreases in tree growth and health. Besides changes in temperature and rainfall, climate change projections for Australia indicate an increase in the frequency and intensity of extreme climatic events. More intense extreme events will have a major impact on tree-dominated ecosystems. Declines in tree health and mass mortality will occur, and associated services, such as food provision and carbon sequestration, will be affected.
In the southwest of Western Australia, for example, 26% of mature trees across ~7,000 hectares of forest died in response to extreme drought and multiple heatwaves in 2010/2011. Similar levels of tree mortality were found across the 18.6 million hectare Mulga Lands bioregion in Queensland in response to the 2003-2007 drought. Dying and dead trees are not only visually disturbing; tree declines also affect species that are dependent on trees for food and shelter. For instance, the Australian Glossy Black-cockatoo showed less breeding success in a drought because their food, she-oak cones, was less available. A further negative effect of tree decline is a potential reduction in long-term carbon storage in forests. Forests play an important role in reducing the effects of climate change by capturing carbon from the atmosphere. Long-lived trees are extremely valuable in capturing and locking-in carbon for prolonged periods (>150 years). Increasing tree mortality rates with no additional seedling recruitment are therefore highly undesirable for the mitigation of climate change.
Whether climate change will have a permanent (undesirable) effect on forested ecosystems needs to be determined by consistent monitoring. Finding out where, when, and what kind of changes are likely to occur in the landscape through modelling will be critical to effectively adapt to the future climate.

Hot Topic Lead Author: 
Name: Dr Niels Brouwers
Phone: +61893602737

Date approved: 
Monday, November 30, 2015 - 15:53
ID Title Location Type
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7946 van Mantgem P. J., Stephenson N. L., Byrne J. C., Daniels L. D., Franklin J. F., Fulé P. Z., Harmon M. E., Larson A. J., Smith J. M., Taylor A. H. & Veblen T. T. (2009) Widespread increase of tree mortality rates in the western United States. Science 323, USA, western United States observational
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7948 Cameron M. (2006) Distribution and cone production in Allocasuarina diminuta and A. gymnanthera (Casuarinaceae) in central New South Wales. The Rangeland Journal 28, 153-61. Australia, New South Wales, Goonoo State Forest (31◦00 S, 148◦80 E), 40 km north of Dubbo in central NSW. observational
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7796 Allen C. D., Macalady A. K., Chenchouni H., Bachelet D., McDowell N., Vennetier M., Kitzberger T., Rigling A., Breshears D. D., Hogg E. H., Gonzalez P., Fensham R., Zhang Z., Castro J., Demidova N., Lim J.-H., Allard G., Running S. W., Semerci A. & Cobb N Global review
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7798 Brouwers N., Matusick G., Ruthrof K., Lyons T. & Hardy G. (2013) Landscape-scale assessment of tree crown dieback following extreme drought and heat in a Mediterranean eucalypt forest ecosystem. Landscape Ecology 28, 69-80. Australia, southwest Western Australia, Northern Jarrah Forest region observational
7799 Brouwers N. C., Mercer J., Lyons T., Poot P., Veneklaas E. & Hardy G. (2012) Climate and landscape drivers of tree decline in a Mediterranean ecoregion. Ecology and Evolution 3, 67-79. Australia, southwest Western Australia observational
7800 Bureau of Meteorology. (2015) Climate change and variability. Australian climate variability & change - Trend maps. Commonwealth of Australia, URL: Australia N/A
7801 Carnicer J., Coll M., Ninyerola M., Pons X., Sanchez G. & Penuelas J. (2011) Widespread crown condition decline, food web disruption, and amplified tree mortality with increased climate change-type drought. Proceedings of the National Academy of Sciences Europe and Spain observational
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7810 IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA Global review
7811 Matusick G, Ruthrof KX, Brouwers NC, Dell B, Hardy GSJ (2013) Sudden forest canopy collapse corresponding with extreme drought and heat in a mediterranean-type eucalypt forest in southwestern Australia. European Journal of Forest Research 132(3): 497-510 Australia, southwest Western Australia, Northern Jarrah Forest region observational
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Dr Niels Brouwers

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Dr Brett Murphy