Hot Topics

Climate Change: trees under pressure

Hot Topics in Ecology

Climate Change: trees under pressure

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.
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