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Ecological Modelling Platform at UTS

Dr Longhui Li

The words “sparsely populated” and “China” don’t normally go together but for Dr Longhui Li growing up in a mountainous region in the west of China meant lots of trees, small villages and a limited transport network.

“My first experience of a train was after graduating from High School in 1997 when I had a 32 hour trip across several Chinese provinces to get to my university. But I couldn’t sleep, it was very exciting as I got to see China’s geography. Before that I only knew it from a text book,” Dr Li said.

Li’s travel bug must have been ignited by that inaugural trip. Before joining UTS in 2010 as a C3 Research Fellow his agricultural meteorology studies, and subsequent research on carbon dioxide and vapour exchange between plants and the atmosphere, had taken him from the Chinese Academy of Sciences (CAS) to the USA, The Netherlands and France. Now, as a member of the Ecological Modelling and Remote Sensing Research Group (EMRS), lead jointly by Profs Alfredo Huete and Qiang Yu, Li is using his passion for research to gain a better understanding of the interactions between vegetation and climate so that crop and land use models can be improved in the face of climate change impacts. Together with colleagues from C3 Terrestrial Echohydrology Research Group (TERG) Dr Li analyses data sets collected via the Oz Flux Network: a network of micrometeorological flux stations located at various sites within Australia and New Zealand where exchanges of carbon dioxide, water vapour, and energy between terrestrial ecosystem and atmosphere are measured continuously over long periods.

“I had a connection with Professor Yu from CAS and Australia has a good reputation within the global Flux-Net community. With C3 UTS has an excellent platform and environment to extend ecological modelling research through collaborations with the Oz Flux Network and CSIRO,” he said.

Li’s current research focus includes the tropical savannah region of Northern Australia: a very significant feature of the Australian landscape, that includes stands of trees, and one that poses a number of issues for ecological and land-surface modellers.

“The annual rainfall is high, around 1700mm, but there is a wet and a dry season. In the wet both the trees and the savannah are ok but in the dry season the trees may undergo water stress. Because I am a modeller I see that when there is sufficient rainfall the model works well but in drought the model does not match the observations. This is the challenge for modellers,” he said.

Dr Li uses data sets collected from the OZ Flux network, including the C3 TERG flux tower located near Alice Springs, to help validate CSIRO’s CABLE model: a model of biosphere atmosphere exchange allowing for interaction between microclimate, plant physiology and hydrology.

The formulae in the CABLE model describe different plant ecophysiological processes - such as photosynthesis and transpiration – and how these processes react to changes in environmental factors like solar irradiation, air temperature, and soil moisture. By combining all the processes – from vegetation, the soil and atmosphere - ecological land-surface models aim to simulate what happens in reality.

“The problem is that because there are lots and lots of different driving variables, for example those related to different types of soils and plants, it is very complex. We can only ever hope to improve the model. Models are only mimics. However by understanding the real processes we can improve the models and even small improvements can make a big change to large scale simulations,” he said.

Dr Li believes that remote sensing technology, as well as new techniques and instrumentation that will allow the ecological processes taking place under the ground to be quantified, will ultimately give modellers like him the essential data needed to do whole earth system research.

“It’s difficult to predict but the next generation of models will be more complex still. All ecological models tend to be coupled to GCMs [General Circulation Models]. Only then will we get a better understanding of how land use change, for example removing savannah or trees to plant crops, will affect global and regional climate,” Li said.

For Li his journey from farming village to inner city campus has also been accompanied by a growth in his research development.

“In my shift from student to scientific researcher I have come to understand the value of research. This research has an economic value, a practical use. There is a connection between my research and the economy and society, which there should be because of the dollars invested,” he said.

 

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