Groups of Species Responding to Soil and Light in the Cerrado

Woody plants in the Cerrado have been understood to comprise two groups: calcicole species responding to soil Al-Ca gradient (CAL) and leguminous species responding to inorganic soil N gradient (LEG). However, the bulk of Cerrado woody flora was not inside these groups. Our main question was whether CAL and LEG are distinct from each other as well as from the bulk of Cerrado species that occur rather in savannas than in quasi-forests (SAV) while responding only to soil variables and light. We performed the study among five soil categories, and measured canopy openness. We evaluated the functional traits of the 34 most relevant species of the studied Cerrado. We measured specific leaf area, bark thickness, leaf nitrogen, leaf carbon, leaf C/N, maximum height, maximum, stem elongation, d15N and d13C. We determined wood density by consulting a database. RLQ and Fouth-corner analyses confirmed CAL and LEG as consistent groups as well as found a third group, the SAV. CAL and LEG were found to dominate plots with low canopy openness; only CAL were negatively associated with aluminium saturation; only LEG were negatively associated with pH; only SAV were negatively associated with inorganic nitrogen and CEC. LEG presented the lowest leaf C/N and the highest leaf N meanwhile SAV presented the highest C/N, the lowest leaf N and the lowest stem elongation. Higher values of d13C in leaves suggest higher water use efficiency for CAL and LEG than for SAV.