Breath-testing the grasslands

Watching the grass growing is proving intensely interesting to researchers in Queensland. At a unique research facility near Townsville scientists are gaining an insight into how climate change might affect more than a quarter of Australian land.

The Free Air Carbon Dioxide Enrichment (FACE) facility was established in 2001 to simulate climate change, allowing researchers to examine potential impacts on tropical grassland systems.

"Glasshouse experiments have given us some understanding of the impacts of climate change at an individual plant level," says CSIRO's Dr Chris Stokes. "But until now, little has been known about how whole ecosystems - with all their interacting components - might respond."

Named OzFACE, the facility is the first of its kind in Australia and the first established in any tropical ecosystem.

The facility comprises 6 rings, each 15m in diameter, that allow regulated delivery of carbon dioxide to the vegetation within them. Each vegetation type under investigation is exposed to different carbon dioxide levels ranging from current levels (370 parts per million) to the projected levels for the year 2070 (550 ppm).

Researchers from CSIRO and James Cook University, with infrastructure support from Queensland Nickel, have been measuring ecosystem response for two full growth seasons.

Early results indicate that higher carbon dioxide levels have enhanced production and made the plants more efficient users of water. This result suggests a possible buffer against rainfall variability and drought for the savanna ecosystem, but was probably favoured by the dryness of the past wet season.

"These are obviously short-term impacts and we will need at least 3-5 years' more data, from wet and dry years, before we'll be able to draw any confident conclusions," says Dr Stokes.

The results of this experiment have important implications for the pastoral industry, water resources, biodiversity for carbon sequestration/storage by savanna vegetation and for other aspects of natural resource management.

"It's important to keep in mind that climate change will produce both opportunities and challenges - for existing land use practices and for the altered environments of the future," Dr Stokes says.

Item provided courtesy of The CSIRO