A UNSW researcher has contributed data and expertise to an international study on the decline of vegetation greenness and water content in Congolese rainforests over the past decade.

Dr Yi Y. Liu, an ARC DECRA Research Fellow in the Climate Change Research Centre, is a co-author of a research letter published online in Nature today.

The study, which was led by University at Albany Professor Liming Zhou, used satellite data to track changes in Central Africa's rainforests.

One of the datasets used was created by Dr Liu for his PhD.*

"I spent my three-year PhD candidature developing a global long-term vegetation optical depth (VOD) dataset to represent the total water content in aboveground vegetation biomass," Dr Liu says.

"After I finished my PhD, I spent nearly all my time exploring how we could use this unique dataset to more comprehensively understand the change of vegetation at any scale - local, regional or global.

"I think this study is a good example of how the dataset can be used."

Dr Liu's long-term VOD dataset is one of a number of independent sources used to identify and verify the pattern of large-scale persistent browning of the Congolese forests.

"You can imagine if a number of independent sources show the same change, it's most likely to reveal what is occurring," Dr Liu says.

He believes the international study will put a spotlight on the light of Congolese rainforests, which have generally been afforded less attention than those in the Amazon and South-East Asia.

"I expect this paper will lead to more analysis of the situation in the Congo," Dr Liu says.

Central African rainforests are the second largest on Earth. The forests have experienced a long-term drying trend but the impact on vegetation dynamics remain mostly unknown because on-site observations have been very limited, the researchers argue.

The researchers say that the implications for the study relate directly to the growing concerns of climate change on rainforests in tropical regions of the world during the next century.

Dr Liu's long-term VOD dataset is not limited to rainforests: it can capture water content changes in grassland, savannah, shrubland and tropical forests over a 20-30 year period.

* UNSW Adjunct Associate Professor Matthew McCabe and Associate Professor Jason Evans, as well as ANU Professor Albert van Dijk and VU Amsterdam Assistant Professor Richard de Jeu supervised Dr Liu's PhD. Dr Liu's PhD thesis was awarded the Malcolm Chaikin Prize for Research Excellence in Engineering, UNSW.

Media contact: Ry Crozier, UNSW Media Office, 02 9385 1933 r.crozier@unsw.edu.au