Variations in soil properties among phytophysiognomies on different geological surfaces in the vegetation complex of Campo Maior in the ecotonal region of the Parnaíba basin in the state of Piauí

Abstract

The determinants of the phytophysiognomies in the vegetation complex of Campo Maior in the ecotonal region of the Parnaíba sedimentary basin in the state of Piaui, an area of transition between the Brazilian savanna (cerrado) and the shrubland vegetation of northeastern Brazil (caatinga), are poorly documented in literature. We investigated the availability of nutrients in the soils associated with such phytophysiognomies. The main hypothesis was that soil properties under different physiognomies are conditioned by geomorphological compartments and soils associated with more open physiognomies have lower availability of nutrients. We sampled soils of six different physiognomies on different geomorphological surfaces. Composite soil samples were collected from the surface 0-20 cm of ten 50 m x 50 m plots of each physiognomy and analysed for soil texture and availability of macro and micronutrients. Principal component analysis of soil properties separated the phytophysiognomies along the first and second axes determined principally by gradients in soil texture and the concentrations of available nutrients. The clay content of forest soils was higher than that of other open physiognomies. Although all soils were dystrophic with less than 50% base saturation, the soil under forest had higher concentrations of organic C, total nitrogen available P, Ca and Mn, confirming the original hypothesis.

DOI:https://doi.org/10.56238/sevened2023.006-058