Any increases in plant growth as a response to climate change will always be restricted by the natural distribution of rainfall, new research has found.
It has been long assumed one significant benefit of climate change will be a huge growth in the world’s grasslands, however, researchers have found this expectation will only be met if rain falls at the right time – in spring.
Rising carbon dioxide levels were expected to create a “bonanza” of grassland productivity, with suggestions of a 20 per cent increase in grassland growth rates as a result of fertilisation effects.
University of Tasmania Associate Professor Mark Hovenden said research revealed that the increase in grassland growth rates would be closer to 6 per cent than 20 per cent.
“We found the fertilisation effect of high carbon dioxide increases as the amount of spring rainfall increases,” Associate Professor Hovenden said
“The fertilisation effect decreases as the amount of rain at other times of the year goes up.
“Growth is, therefore, stimulated more in sites that have most of their rain in spring.”
Grasslands are worth more than $22 billion a year to Australia’s economy and account for more than 40 per cent of agricultural productivity.
Globally, grasslands cover one-third of land area.
The research combined 19 different experiments from Tasmania to Denmark and produced uniform results around the globe.
“Importantly, these results are from actual experiments distributed across the world and show that the response is uniform across all grasslands, despite differences in climate and local conditions,” Associate Professor Hovenden said.
“This is something fundamental about the way this system will respond to the rising carbon dioxide concentration.”