Deciduous trees could benefit more from the rise in [CO2] than evergreens in the Brazilian Cerrado

The Cerrado, a Neotropical savanna, is the second largest vegetation domain in Brazilian territory and presents a gradient of physiognomies. Among the savanna formations, the cerrado stricto sensu stands out. The responses of woody species of the cerrado related to increased CO2 concentration ([CO2]), as predicted by global climate change, may differ among distinct leaf persistence groups. Elevated [CO2] could enhance the resprouting capacity of woody species, which might intensify encroachment in grasslands, such as the cerrado stricto sensu. We investigated the influence of elevated [CO2] (eCO2) on vegetative growth, root non-structural carbohydrates (NSC), and biomass allocation pattern among roots, stems, and leaves in two deciduous and three evergreen cerrado woody species. We carried out the experiment in open-top chambers with five young individuals of cerrado woody species under ambient [CO2] (aCO2) and eCO2 of 430 and 700 ppm, respectively. Measurements occurred in young plants with 294, 379, and 466 days old, i.e., after 104, 189, and 276 days of eCO2 exposition. While the species under aCO2 decreased the NSC in roots on the 189th day, the plants under eCO2 did not show a decrease over time. The deciduous species under eCO2 showed higher RGR at the beginning of the experiment (104 days) than the evergreens species under eCO2. Also, the eCO2 promoted fast leaf development in four out of five studied species (except Anadenanthera peregrina). The characteristics analyzed among the species could demonstrate that the deciduous grown under eCO2 presented higher relative growth rate and root/stem ratio than the species with evergreen habit.