New research to help determine how well forests are adapting to the rising levels of carbon dioxide in the atmosphere has shown drier forests are adapting more rapidly than their wetter cousins.
Water use in dry conditions
The joint Australian-American study, which focused on tropical forests, calculated efficiency of water use amongst plants by observing and comparing how much CO2 they took in and how much water they put back into the atmosphere.
Using this method, the researchers from Swinburne University of Technology and the University of California observed more efficient water use in plants found in the drier forests. They concluded the plants were acclimatising two to three times more quickly to increased CO2 than their wetter equivalents.
The results of this new research could be used to develop refined and improved models of rainfall prediction, as well as having implications for how water is stored and used in areas where plants are known to release less water back into the atmosphere.
Professor Mark Adams, Lead Researcher of the project at Swinburne University of Technology, said the study was strengthened by using data from multiple sources globally.
“Our findings are not reliant on any one study or research group. Many previous studies have observed that water-use efficiency rises with atmospheric carbon dioxide. What hasn’t been clear is the rate of change. Once we focused on that, novel patterns emerged,” said Professor Adams.
The study also showed leguminous trees use water more efficiently on average than non-legumes. This is particularly significant for Australia, as much of the country’s inland tropical and sub-tropical region is dominated by Acacias, which are leguminous.
“If thoseAcaciawoodlands are transpiring less water as a result of the rise in atmospheric carbon dioxide, then we have a serious job ahead to understand potential consequences for run-off and infiltration to replenish ground water, as well as impacts on rainfall,” said Professor Adams.
Growth responses to increased CO2
Elsewhere in Australia, a collaboration between the Australian National University, the University of Western Sydney and the CSIRO is leading the way in biological science relating to climate change.
As part of an initiative known as The Forests Project, a potential strategy is being developed to identify tree species which demonstrate strong growth in response to increased levels of CO2, as well as the genetic attributes that enable these responses. This new approach is inexpensive and less labour-intensive when compared to existing procedures.
While the rise in atmospheric CO2 presents many challenges globally, it can actually lead to increased forest production and bio-sequestration via what is known as the CO2 fertilisation effect. Essentially, increasing levels of CO2 lead to increased photosynthesis, meaning improved plant growth.
The project worked by measuring Eucalyptus seedling growth compared to increased levels of atmospheric CO2. The idea was to explore whether there are genetic differences between various genotypes within species, with the hope of using this information to identify the genes involved in controlling this highly useful biological response.
Work to draw conclusions of causality and underlying mechanism is ongoing, with further experiments and funding required.
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