Forest Drought and Mortality PDF Print E-mail

Improving predictions of drought-induced mortality and its consequences for Net Primary Production in Australian forests

 

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Project overview


Rising atmospheric CO2 is driving changes in climate already being observed across Australia. Across southern Australia rainfall is declining, temperatures have increased (mean increase ~ 0.9ºC since 1910) and the frequency of heat waves has increased in each decade since the 1950’s. These all affect ecosystem function and the capacity to store carbon in terrestrial ecosystems.

Forest mortality events associated with changing climates have been observed in most of the world’s biomes (Allen et al. 2010) including Australia (Fensham and Fairfax 2007; Mitchell et al. under review) and affect forest productivity and ecosystem processes. Predictive modelling is a key tool for examining the net primary production and carbon sequestration of Australia forests, yet commonly used tools do not account for forest mortality (Roxburgh et al. 2005).

Key reasons for this include: (1) lack of a common understanding of thresholds in physiological responses to changing climates; and (2) lack of appropriate data from field observations and experiments for model validation. This makes it extremely difficult to address issues such as vulnerability of forest ecosystems to future climates; the consequences of increasing mortality for carbon sequestration; and how biodiversity might be affected by future mortality events.

Our Working Group will address this gap by bringing together field and experimental researchers, modellers, and end-users focussed on native and managed Australian forest/woodland ecosystems. Undertaking a multidisciplinary analysis, we will integrate our current understanding of forest mortality with stand and landscape-level processes to determine forest vulnerability under future climates. Importantly, this exercise will increase our capacity to predict future climate related mortality events through development of a living database which is continually expanded and utilised. Potential strategic applications include; improved management of carbon and biodiversity plantings, improved modelling of terrestrial C stores and better definition of the role of forests in climate change mitigation.

References

Allen, C.D., A.K. Macalady, H. Chenchouni, D. Bachelet, N. McDowell, M. Vennetier, T. Kitzberger, A. Rigling, D., D. Breshears, E.H. Hogg, P. Gonzalez, R. Fensham, Z. Zhang, J. Castro, N. Demidova, J.-H. Lim, G. Allard, S.W. Running, A. Semerci and N. Cobb (2010). A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests. Forest Ecology and Management 259: 660-684.

Fensham, R.J. and R.J. Fairfax (2007). Drought-related tree death of savanna eucalypts: Species susceptibility, soil conditions and root architecture. Journal of Vegetation Science 18: 71-80.

Mitchell, P.J., A.P. O'Grady and E.A. Pinkard (under review). Defining past and future climate drivers of drought induced tree mortality: a case study from southern Australia. Nature Climate Change

Roxburgh, S.H., S.L. Berry, T.N. Buckley, B. Barnes and M.L. Roderick (2005). What is NPP? Inconsistent accounting of respiratory fluxes in the definition of net primary production. Functional Ecology 19: 378-38.

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Dead Eucalyptus regnans following wildfire in the Australian Alps (Photo Duursma) Dying Eucalyptus pulchella trees in the Hobart surrounds 2010 (photo O’Grady)

 

 

For further information about this group please This e-mail address is being protected from spambots. You need JavaScript enabled to view it the Principal Investigator: Anthony O'Grady This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

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Products and outcomes


 

Mortality map

A key component of the drought mortality working group is to explore and define patterns in mortality across Australia to improve understanding of ecosystem and species vulnerabilities to drought. To meet this objective we are developing a living database of observed mortality sites that will incorporate data contributed from published papers and other literature, forest management databases and unpublished work. This could form part of a multi-layered, map-based data portal that provides an integrated picture of current/future shifts in climatic zones, drought history and ecosystem response across Australia.


ACEAS Map

 

This map is a collection of observed tree mortality sites from across Australia. The sites are based on documented drought-related mortality events from published reports and journal articles.

 

Papers

 

 

Mitchell P., O’Grady, A.P., Pinkard, E.A., Brodribb, T.J., Arndt, S.K., Blackman, C.J., Duursma, R.A., Fensham, R.J., Hilbert, D.W., Nitschke C.R., Norris, J., Roxburgh, S., Ruthrof, K.X. & Tissue, D. T. (in press) An eco-climatic framework for evaluating the resilience of vegetation to water deficit. Global Change Biology. doi: 10.1111/gcb.13177

To see the paper click here

 

O'Grady A.P., Mitchell P.J.M., Pinkard E.A., Tissue D.T. (2013) Thirsty roots and hungry leaves: unravelling the roles of carbon and water dynamics in tree mortality. New Phytologist 200(2): 294-297. doi: 10.1111/nph.12451


To see the paper click here


Final report


Download their final report [1.3 MB]

Download PDF

 


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Workshop Reports


 

 

Workshop 1 Report (5 - 9 November 2012)

The first meeting for the "dead wooders" was held at the University of Queensland’s Moreton Bay Marine Research Station on North Stradbroke Island.

The aims of the meeting were to bring together people from a range of disciplines to explore the role of forest mortality in ecosystem productivity and carbon stores. The diverse participants contributed to what was a very useful meeting.

Large scale forest mortality has captured the attention of research groups around the world, and there is a push to synthesise the knowledge surrounding these events to better understand the drivers and consequences. In Australia, forest mortality associated with drought has always occurred and one of the first questions to emerge is: ‘what is ecologically relevant drought?’ This question became a defining theme for the first couple of days of our meeting.

We recognised that while drought is a pervasive feature of the Australian landscape, defining drought and its attributes remains difficult. Australia has historically experienced severe droughts capable of inducing tree mortality, and by studying the characteristics of these droughts we have been able to define characteristics common to all droughts that have resulted in mortality. This provides a baseline from which we address a critical question - how do we define “global change type” droughts from those that have occurred in the past.

The second major theme of the meeting focused on characterising and defining the differential sensitivity of species to these drought characteristics. Australia has a long history of water relations research and as part of this working group’s activities we have been compiling an Australian database of these traits. In combination with the recently released global database on plant hydraulic vulnerability (e.g. Choat et al 2012 Nature, 491: 752-755) and rapidly expanding information on leaf hydraulics,  we are now in a position to explore species vulnerable within and across ecosystems. This information will be invaluable in predicting changes in ecosystem structure and function under changing climates.

The group had an informal meeting at the ESA conference in Melbourne in December and plans to meet again in April 2013.

 

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Back left to right: David Hilbert (CSIRO), Katinka Ruthrof (Murdoch Uni), Stefan Arndt (Uni of Melbourne Uni), Jaymie Norris (Dept of Sustainability and Environment, Vic), Anthony O'Grady (CSIRO), David Tissue (Uni of Western Sydney), Craig Nitschke (Uni of Melbourne). Front left to right: Tim Brodribb (Uni of Tasmania), Libby Pinkard (CSIRO) and Patrick Mitchell (CSIRO)

 

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Workshop 2 Report (22 - 26 April 2013)


The second meeting of the “dead wooders” - the drought and Australian terrestrial carbons stores working group - was held at the Point Lookout Surf Club on North Stradbroke Island between the 22nd and 26th of April 2013. The composition of the group varied slightly from the first meeting with incoming members being Chris Blackman (Macquarie University), Remko Duursma (University of Western Sydney) and Stephen Roxburgh (CSIRO Ecosystem Sciences). Unfortunately a couple of members Rod Fensham and Jaymie Norris were unable to make the meeting.

 

The second meeting picked up where the first meeting left off. In the interim there was considerable work done on building a database of water relations traits for Australian species. Currently the database contains relevant traits for over 300 species and water relations traits including those derived from pressure volume curves for over 180 species. Analysis of this data set is ongoing. In addition to these, a draft manuscript on defining ecologically relevant drought was table at the meeting. This work was being lead by Pat Mitchell, and there was considerable progress made during the meeting on progressing this manuscript. Importantly the paper explores how drought and its impacts on Australian ecosystems might be considered in an ecologically relevant way. The manuscript is close to being finalised and is expected to be submitted for publication by the end of the year.

 

A second theme explored during the meeting was that of defining the limits of plant function. This theme aims to explore our existing knowledge of plant traits and their relationships with climates and to explore the interplay between the adaptive significance of these traits to climate. This works build on the analysis of Choat et al. (2005) work examining global convergence in plant hydraulic traits to incorporate new and existing knowledge of plant water elations and leaf hydraulics in an Australian context. We are currently analysing these data sets with the aim of identifying the climatic tolerance of for many keystone Australian species. A manuscript will be prepared for submission to an international journal.

 

Two data sets will be available through the ACEAS and TERN data portal. The observations of Australian Mortality events and the database of plant water relations for Australian species. In general the meeting was extremely enjoyable and the venue brilliant. Collaboration within the group continues through the preparation of research proposals and manuscripts.

 

Refrerence:

Choat B, Ball MC, Luly JG (2005) Hydraulic architecture of deciduous and evergreen dry rainforest tree species from north-eastern Australia. Trees 19:305-311

 

 

A second theme explored during the meeting was that of defining the limits of plant function. This theme aims to explore our existing knowledge of plant traits and their relationships with climates and to explore the interplay between the adaptive significance of these traits to climate. This works build on the analysis of Choat et al. (2005) work examining global convergence in plant hydraulic traits to incorporate new and existing knowledge of plant water elations and leaf hydraulics in an Australian context. We are currently analysing these data sets with the aim of identifying the climatic tolerance of for many keystone Australian species. A manuscript will be prepared for submission to an international journal.
Two data sets will be available through the ACEAS and TERN data portal. The observations of Australian Mortality events and the database of plant water relations for Australian species. In general the meeting was extremely enjoyable and the venue brilliant. Collaboration within the group continues through the preparation of research proposals and manuscripts.

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Workshop 2 Participants

Back row left to right: Tony O'Grady (CSIRO), Katinka Ruthrof (University of Western Australia), Dave Tissue (University of Western Sydney), Remko Duursma (University of Western Sydney), Libby Pinkard (CSIRO), Tim Brodribb (University of Tasmania), Chris Blackman (Macquarie University).
Front row left to right: Craig Nitschke (University of Melbourne), Pat Mitchell (CSIRO), Stephen Roxburgh (CSIRO) and Stefan Arndt (University of Melbourne).

 

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Last Updated on Friday, 19 February 2016 18:15