Drought, deluge and elevated CO2 – A large-scale approach to understanding climate change

Predictions for future climate are varied, however, what is certain is that we will see changes to both temperature and precipitation regimes across the globe. While the impacts of temperature are widely assessed, it is not as common to see experiments that assess changes to precipitation. It could be that future precipitation is harder to estimate, or maybe because manipulative experiments are more difficult. Experiments that look at all projected aspects of climate change are important and Associate Professor Sally Power, an ecosystems ecologist with Hawkesbury Institutes, has been doing some fantastic work across a range of ecosystems. Baker visited Macquarie University this month to provide an overview of three key projects that she has been lucky to be a part of.

Professor Power is originally from the UK and she completed her undergraduate, post graduate and PhD at the Imperial College of London. Following 5 years of research in the UK she moved to Melbourne for work. It was an exciting job opportunity from the Hawkesbury Institute for the Environment (HIE) that bought her to Sydney as deputy theme leader for the Ecosystem Function & Integration research theme. Her research broadly focuses on the impacts of atmospheric pollution and climate change on the structure and functioning of terrestrial ecosystems. No stranger to recognition, Power has been awarded a number of awards in the last 10 years, she was a Council member of the British Ecological Society from 2004 – 2007 and is currently a Steering Committee member for the Ecological Continuity Trust and the Committee on Air Pollution Effects Research.

Figure 1: DIRECT experiment (Source: Imperial College London)

Figure 1: DIRECT experiment (Source: Imperial College London)

While at the Imperial College in London, Power worked on an experiment called DIRECT (Diversity, Rainfall and Elemental Cycling in a Terrestrial Ecosystem). Rainfall predictions for the UK are a 30% reduction in summertime rainfall and a 15% increase in winter rainfall by 2100. The DIRECT experiment sought to understand the effects of rainfall change on the function of a grassland ecosystem and how having a diverse range of plant traits (grasses, perennials and annuals) buffered these changes. Surprisingly, having a diversity of plant traits did not make a difference to ecosystem processes. Rather, it was the abundance of perennial species which provided better resistance through deeper rooting systems and nutrient uptake processes  (Fry et al. 2013). While future studies should include factors such as temperature and CO2, this research is key in providing useful strategies for future management of grassland ecosystems.

More recently, Professor Power has been involved in experiments a little closer to home, working on rainfall experiments in Sydney. Best estimate models predict an overall reduction in annual rainfall from 20-30% and Power has been working to understand these impacts. The DRI-Grass experiment (Drought and Root herbivore Interaction in a Grassland ecosystem) is a study, which not only looks at changes to rainfall, but it also looks to understand the impacts on root herbivores.  The numbers of root herbivores underground can exceed mammals grazing aboveground and so grasslands can be particularly susceptible to changes in the underground abundance herbivores (Johnson et al. 2014). Power explained that root herbivores are susceptible to changes in rainfall and so there is potential for substantial influence to the ecosystem. The experiment started in June last year and beetles were only added to the plots this year so outcomes from this study so far are minimal. Similar studies which have assessed temperature and CO2 have found significant impacts (Johnson et al. 2014, Tariq et al. 2013) and so it will be interesting to see the findings from the DRI-Grass experiment.

Some of the most exciting work at HIE is an experiment called EucFACE (Eucalyptus Free Air CO2). EucFACE is Australia’s largest climate change research experiment based in the Cumberland Plain woodland in Sydney’s Hawkesbury district. It is a unique experiment that allows the simulation of future projections of atmospheric CO2 in large outdoor plots (figure 2), and the first of its kind in the Southern Hemisphere.

Figure 3: The EucFACE experiment site in the Cumberland Plains Woodland (Source:www.thinkoholic.com)

Figure 2: The EucFACE experiment site in the Cumberland Plains Woodland (Source:www.thinkoholic.com)

The rings are an impressive 28m high x 25m wide and it provides a CO2 at mid-century estimates of 550ppm. Results are limited so far but one of the most interesting observations to date is the increase in phosphate availability. In fact, as soon as the CO2 was turned on there was an increase in soil phosphate. The reasons for this are not known yet but Power certainly finds it intriguing. Power has some ideas, which include soil respiration rates or increased root biomass but whatever the driver, it certainly provides an interesting topic for future research.

The work that Power has been involved is not only impressive with regards to size and scale but what it aims to understand. We have not previously been able to look at climate change impacts on large scale communities and given the technology available we can start to look increased CO2 coupled with temperature and rainfall. Multifaceted experiments on a large scale are what we need if we are to get a thorough understanding of how our ecosystems will manage and adapt in the future.

References:

Fry E.L., Manning P., Allen D.G.P., Hurst A., Everwand G., Rimmler M. & Power S.A. 2013. Plant Functional Group Composition Modifies the Effects of Precipitation Change on Grassland Ecosystem Function. PLoS ONE 8(2):e57027

Hawkesbury Institute for the Environment (2014) EucFACE. Accessed 20 May 2014. http://www.uws.edu.au/hie/facilities/face

Johnson, S. N., Lopaticki, G., & Hartley, S. E. (2014). Elevated Atmospheric CO2 Triggers Compensatory Feeding by Root Herbivores on a C3 but Not a C4 Grass. PloS one, 9(3), e90251.

Tariq M., Wright D.J., Bruce T.J.A. & Staley J.T. 2013. Drought and Root Herbivory Interact to Alter the Response of Above-Ground Parasitoids to Aphid Infested Plants and Associated Plant Volatile Signals. PLoS ONE 8(7): e69013

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About loutosetto

A research masters student currently studying at Macquarie University. My interests are in coastal marine ecosystems. I like the interaction between the urban and the marine environments and the specialised environments that the fauna have evolved to survive in such variable environments.
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