Soil attributes and classes determining tropical savanna physiognomies at Assis Ecological Station, São Paulo State, Brazil

Abstract

The Cerrado vegetation encompasses a mosaic of physiognomies ranging from "campo limpo" (mainly grassland) to "cerradão" (forest type of vegetation). This transition of types of vegetation is thought to be associated to soils as well as to other factors, such as climate and fire. The understanding of those associations is essential for managing the already small extension of cerrado remnants. This study aims to investigate how soil physical, physico-hydrical and chemical attributes relates to the cerrado physiognomies at Assis Ecological Station, SP, that are free from disturbance for the last 44 years. Composite soil samples of the 0-20 and 60-80-cm layers were characterized regarding particle size distribution (PSD) and macro and micronutrients at 30 permanent plots of 1000 m2, representing the physiognomies of typical cerrado, dense cerrado and cerradão. These data are already collected and available, and will be analized with vegetation structure data by regression and correlation. In 2 m-deep pits at 15 permanent plots representing the same physiognomies described above, soil morphology will be described and soil profile samples will be collected for physical, physico-hydrical and chemical characterization and soil classification. The Genuchten-adjusted soil water retention curve parameters, and chemical and PSD soil variables of the soil profiles will be analyzed by multivariate analyses (Cluster, Principal Component and Canonical Correspondence-CCA - Analyses) in association with vegetation structure (basal area, density and biomass) and floristic composition data, data already collected and available. Distribution of vegetation and soils (environmental) data in the CCA ordination axis will be used to infer the role of soil attributes in determining the studied cerrado physiognomies. (AU)