Soil-vegetation relationships in cerrado (Brazilian savanna) and semideciduous forest, Southeastern Brazil

Several studies pointed out soil properties as the prime determinant of cerrado (the Brazilian savanna) physiognomies, and a gradient from "campo cerrado" (a shrub savanna) to "cerradão" (a tall woodland) has been correlated with a soil fertility gradient. Based on this hypothesis, we investigated soil-vegetation relationships in the Pé-de-Gigante Reserve (São Paulo State, Southeastern Brazil). We randomly distributed 10 quadrats (10 × 10 m) on each of the following physiognomies: "campo cerrado", "cerrado sensu stricto", "cerradão", and seasonal semideciduous forest, previously defined by the analysis of satellite images (LANDSAT-5). We sampled the woody individuals with stem diameter > 3 cm at soil level, identifying their species. In each quadrat, we collected soil samples at the depths of 0-5, 5-25, 40-60, and 80-100 cm, and determined pH, K, Ca, Mg, P, Al, H + Al, base saturation, aluminium saturation, cation exchange capacity, and percentage of sand, clay and loam. Obtained data were submitted to a canonical correspondence analysis (CCA) and to a detrended correspondence analysis (DCA). Our results showed a clear distinction between semideciduous forest and the cerrado physiognomies, based in soil parameters. The former was related to higher concentrations of cations and clay in the soil, while the latter was related to higher concentrations of exchangeable aluminium in the soil surface. The three cerrado physiognomies - "campo cerrado", "cerrado sensu stricto", and "cerradão" - could not be distinguished considering plant density and the analysed soil features.