Pedogenesis in a topo-climosequence in the Agreste region of Pernambuco

Carlos Roberto Pinheiro Junior,Ademir Fontana,Thaís De Andrade Corrêa Neto,Lucia Raquel Queiroz Pereira Da Luz,Marcos Gervasio Pereira

doi:10.5935/1806-6690.20190021

Abstract

The Borborema Plateau is characterized by different stages of relief evolution, which modify the climate and vegetation, and where high-altitude tropical forests can be seen surrounded by caatinga. The aim of this study was to characterize the soils of a topo-climosequence in the Agreste region of the State of Pernambuco, and evaluate the influence of the relief and climate on the pedogenesis. A topo-climosequence was selected, and trenches were opened in the geomorphological features of high-altitude forest (P1), between forest and pediplane (P2) and on a pediplanation surface (P3 and P4). A morphological description and a physical, chemical and micromorphological characterization were carried out. In general, the soils are sandy, with the predominance of a single-grain structure or weak aggregation. Higher values for pH, S, V% and assimilable P were found on the lower parts of the landscape. From the micromorphological analysis, the incipient development of pedogenic structures was detected in the C horizon in P1 and P3, clay translocation in P2 and the degradation of iron micronodules in P4. The P1 and P3 profiles were classified as Neossolos Regoliticos Distroficos espessarenicos (Regolsols), the P2 profile as a Argissolo Amarelo Distrofico tipico (Alisol), and P4 as an Planossolo Haplico Eutrofico arenico (Planosol). Soil variation in the landscape was determined by climate, relief and parent material. Micromorphology was efficient in detecting attributes not seen in the field, such as incipient aggregation in the Neossolos Regoliticos (Regosols) and the degradation of iron micronodules in the Planossolo Haplico (Planosol).

Highlights

Among the factors that influence soil formation, relief and climate are most often considered the main determinants of pedogenesis due to their influence on water flow and chemical weathering
The district of Jurema, located in the Agreste region of Pernambuco, is inserted in the Borborema Plateau, characterized by different stages of relief evolution, which is reflected in the variations in climate, plant cover and predominant lithostructure (GURGEL et al, 2013; RODAL; BARBOSA; THOMAS, 2008)
The topographic variations in the region promote changes in the climate and the occurrence of orographic rainfall with indices greater than 1,000 mm year-1 in the highest parts of the landscape, where the altitude can reach 900 m. Such conditions are responsible for the formation of pockets of moisture where ombrophilous, evergreen, and semi-evergreen forests, known as high-altitude tropical forests, can be seen, surrounded by caatinga vegetation with a semi-arid climate (RODAL; BARBOSA; THOMAS, 2008)

Summary

Introduction

Among the factors that influence soil formation, relief and climate are most often considered the main determinants of pedogenesis due to their influence on water flow and chemical weathering. Variations in relief are responsible for a number of changes in the characteristics and attributes of the soil, as they govern both the water dynamics of the landscape and drainage, controlling the intensity of formation processes. The topographic variations in the region promote changes in the climate and the occurrence of orographic rainfall with indices greater than 1,000 mm year-1 in the highest parts of the landscape, where the altitude can reach 900 m. Such conditions are responsible for the formation of pockets of moisture where ombrophilous, evergreen, and semi-evergreen forests, known as high-altitude tropical forests, can be seen, surrounded by caatinga vegetation with a semi-arid climate (RODAL; BARBOSA; THOMAS, 2008)

Objectives

Methods

Results

Conclusion