Image copyright M.Venturas
By Mark Kinver Environment reporter
26 November 2019
Forests can cope with a warming world if – and only if – temperature rises increase in line with increases in atmospheric carbon dioxide.
Increased CO2 allows trees to develop physiological characteristics, such as greater foliage, that can cope with higher temperatures.
But researchers warn that a break in the temperature-CO2 increase ratio could trigger mortality in forests.
The findings appear in the Proceedings of the National Academy of Sciences.
“Nobody had really considered incorporating the ability of trees, the forests, to adjust to novel conditions and to acclimate,” explained co-author John Sperry from the University of Utah.
“So it felt like we were bringing in two new approaches to this longstanding question of whether CO2 or warming were going to play out in the future.”
Delicate balancing act
Higher levels of atmospheric CO2 allow trees to consume relatively less water and photosynthesise more, whereas increased temperatures result in trees consuming more water and photosynthesising less.
Using a unique model that took into account the trees’ physiology, Prof Sperry and his colleagues reached a rather surprising conclusion.
“What’s interesting is that it is not the magnitude of the CO2 increase or the magnitude of the warming, it was the ratio of the two,” he told BBC News.