title: Elevated CO2enhances resprouting of a tropical savanna tree.
abstract: The savannas (cerrado) of south-central Brazil are currently subjected to frequent anthropogenic burning, causing widespread reduction in tree density. Increasing concentrations of atmospheric CO2could reduce the impact of such frequent burning by increasing the availability of nonstructural carbohydrate, which is necessary for resprouting. We tested the hypotheses that elevated CO2stimulates resprouting and accelerates replenishment of carbohydrate reserves. Using a factorial experiment, seedlings of a common Brazilian savanna tree, Keilmeyera coriacea, were grown at 350 ppm and 700 ppm CO2and at two nutrient levels. To simulate burning, the plants were either clipped at 15 weeks or were left unclipped. Among unclipped plants, CO2and nutrients both stimulated growth, with no significant interaction between nutrient and CO2effects. Among clipped plants, both CO2and nutrients stimulated resprouting. However, there was a strong interaction between CO2and nutrient effects, with CO2having a significant effect only in the presence of high nutrient availability. Under elevated CO2, carbohydrate reserves remained at higher levels following clipping. Root total nonstructural carbohydrate remained above 36% in all treatments, so carbohydrate reserves did not limit regrowth. These results indicate that under elevated CO2this species may be better able to endure the high frequency of anthropogenic burning in the Brazilian savannas.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA, , , , , , US.
authors.forename: W A
authors.initials: WA
authors.lastname: Hoffmann
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA, , , , , , US.
authors.forename: F A
authors.initials: FA
authors.lastname: Bazzaz
authors.affiliation: USDA-Agriculture Research Service, Forage and Range Research, Utah State University, Logan, UT 84322-6300, USA, , , , , , US.
authors.forename: N J
authors.initials: NJ
authors.lastname: Chatterton
authors.affiliation: USDA-Agriculture Research Service, Forage and Range Research, Utah State University, Logan, UT 84322-6300, USA, , , , , , US.
authors.forename: P A
authors.initials: PA
authors.lastname: Harrison
authors.affiliation: Department of Botany, Duke University, Durham, NC 27708, USA, , , , , , US.
authors.forename: R B
authors.initials: RB
authors.lastname: Jackson
keywords: Carbohydrate; Cerrado; Elevated CO2; Fire; Key words Savanna