Leaf chemistry of woody species in the Brazilian cerrado and seasonal forest: response to soil and taxonomy and effects on decomposition rates

摘要

The Brazilian cerrado occurs interspersed with the semi-deciduous seasonal forest, and soil fertility is considered as the main determinant of the abrupt transitions between both vegetation types. We aimed to study patterns across chemical traits of green leaves in 121 cerrado and seasonal forest woody species from southeastern Brazil, their response to soil nutrient status, and their effects on decomposition rates. We compared leaf traits of both cerrado and forest species and constructed multilevel models to account for partitioning of variance in each trait. We calculated the community-weighted mean of each trait to assess their response to soil nutrient status and their effects on decomposition rates of standard plant material. Most of the traits were significantly correlated among themselves, with cerrado species having lower nutrient concentrations than the seasonal forest. Taxonomy accounted for 52 % of the total variance in leaf traits, whereas vegetation type accounted for 19 %. All leaf traits but leaf manganese and aluminium concentrations were significantly related to soil properties. Decomposition rates were affected indirectly by soil features through its effects on leaf traits. Contrary to the expected, the higher the leaf nitrogen concentration in the surrounding litter, the lower the decomposition rate. Even with a large effect of taxonomy on leaf nutrient-related traits, soil exerted an important role on the chemical traits. Strategies of both cerrado and seasonal forest species were carried out through multi-element control of soil on leaf nutrient composition. The effect of such different strategies on functioning was, however, less prominent.