Nutritional strategies in woody species of cerrado and semi-deciduous seasonal forest.

Abstract

The savanna is a tropical and subtropical biome, where the herbaceous layer is almost continuous, interrupted only by shrubs and trees at varying densities, with growth and reproductive patterns linked to climatic seasonality and to the occurrence of fires. Since savannas appear in climates that also harbour forests, only the climate is not enough to explain the occurrence of the former. One of the factors postulated to explain the occurrence of savannas in areas whose climate allows forests is nurient-poor soils. Although the cerrado varies from grassland to woodland, most of its physiognomies lie within the definition of savanna. As long as nutrient availability, especially nitrogen and phosphorus, is one of the main resources that determines the presence and abundance of savanna and forest species, we will analyse nutritional strategies of a congeneric pair, Handroanthus aureus, a cerrado species, and Handroanthus impetiginosus, a seasonal forest species, through four treatments: (1) all nutrients, (2) all nutrients but nitrogen,(3) all nutrients but phosphorus, and (4) all nutrients but nitrogen and phosphorus. During three months, we will analyse the individuals, measuring how long cotyledons persist, the time for the appearance of the first pair of leaves, height, leaf area, root:shoot ratio, total biomass, and leaf nitrogen and phosphorus concentrations. We will compare the treatments using analyses of variance. Since savanna species tend to be adapted to oligotrophic conditions, we expect that the cerrado species will be less sensitive to nutrient depletion than the forest species. (AU)