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

Abstract

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.