Paper Reviewed
Souza, J.P., Melo, N.M.J., Pereira, E.G., Halfeld, A.D., Gomes, I.N. and Prado, C.H.B.A. 2016. Responses of woody Cerrado species to rising atmospheric CO2 concentration and water stress: gains and losses. Functional Plant Biology 43: 1183-1193.

The Brazilian Cerrado occupies approximately 21 percent of the country and is considered the most diverse savanna in the world, containing some 7,000 species of herbaceous plants, shurbs, vines and trees. Despite the uniqueness and ecological importance of this incredible tropical savanna ecoregion, in the words of Souza et al. (2016), "few studies have focused on the effects of climate change on the ecology of Cerrado species," a shortcoming that the six-member Brazillian research team set out to address. As their contribution to the subject, Souza et al. conducted an experiment to "evaluate the changes in functional and phenological traits in woody Cerrado seedlings that were grown under high CO2 and low soil water availability."

To accomplish their objective, the scientists grew 30-day-old seedlings of three native Cerrado tree species (Hymenaea stigonocarpa, Solanum lycocarpum and Tabebuia aurea) for 515 days in open-top chambers under ambient (430 ppm) or elevated (700 ppm) CO2 concentrations. Various measurements pertaining to the growth and development of the plants were then made after 60, 150, 240, 330, 420 and 510 days of CO2 treatment. Additionally, half of the plants in each CO2 treatment were subjected to water stress by halting irrigation for one month prior to surveying their responses after 330, 420 and 510 days of CO2 enrichment. Both prior to the water stress treatments and upon completing morphophysiological surveys, all seedlings were watered daily until the next water stress cycle.

In discussing their results, Souza et al. say they "found that the ecophysiological responses of woody Cerrago plants to isolated effects of increased CO2 were positive," and that "even with water stress, Cerrado species under elevated CO2 had better growth." In light of such findings, the researchers conclude that "in future climatic scenarios, in ecosystems with episodic droughts such as Cerrado vegetation, water stress will be attenuated because of the increased atmospheric CO2. And that would be yet another example of a future benefit of atmospheric CO2 enrichment awaiting the biosphere.