Chemistry, mineralogy and micropedology of highland soils on crystalline rocks of Serra da Mantiqueira, southeastern Brazil

Abstract

A typical altitudinal sequence of four soil profiles from one of the uppermost areas of the Mantiqueira Highlands (Minas Gerais State, southeastern Brazil) was studied regarding physical, chemical, mineralogical and micromorphological attributes. The soils were classified as a Terric Haplosaprist, a Humic Xanthic Hapludox, a Typic Haplorthod and a Humic Psammentic Dystrudept. All soils are gibbsitic, highly acidic and distrophic, with high aluminium saturation. The high organic carbon content and coarse texture favour the occurrence of podzolization. Intense hydrolysis and mineral dissolution occur in the studied pedoenvironments, with the presence of adsorbed Al polymers and organic matter bound Al forms. Podzolization can only be confirmed with the combined analysis of soil humic fractions, Al forms and micromorphological attributes. The conspicuous presence of gibbsite is attributed to past conditions of deep weathering and saprolite formation. Closed nutrient cycling is essential for environmental sustainability due to the very low nutrient reserve of soils and deep pre-weathered saprolites. The highland subtropical environment is an important site of natural carbon immobilization in the tropics in which histic/humic horizons are the most important loci of carbon inputs. D

Carbon and nitrogen stock and fluxes in coastal Atlantic Forest of southeast Brazil: potential impacts of climate change on biogeochemical functioning

“…From 100 m asl to 1000 m asl there was a 7 Mg ha -1 increase in the nitrogen stock (Table 1). The same high concentration of carbon and nitrogen was also found for soils of the Serra da Mantiqueira located at higher altitudes (Dias et al, 2003;Benites et al, 2005;Simas et al, 2005).…”

Micromorphology and Pedogenesis of Mountainous Inceptisols in the Mantiqueira Range (Mg)

“…Mountainous soils in high altitude subtropical regions constitute unique and fragile environments, with highly endemic vegetation (altimountainous cloud forests) that are important refuges for animal and plant life (Simas et al, 2005). In Southeastern Brazil, the Mantiqueira Range is a 500 km long Archean rocky mass that borders three States and often reaches altitudes between 1,500 and 2,900 m a.s.l.…”

Argilominerais em solos de manguezais da costa brasileira

“…A alta relação d 100 /d 101 para os picos de quartzo é um bom indicativo para confirmar o caráter alóctone e diagenético deste mineral. O quartzo é um mineral comum na fração silte dos solos tropicais bem desenvolvidos, presentes sobre litologias semelhantes a muitas áreas adjacentes aos manguezais estudados (SIMAS et al, 2005;FURIAN et al, 2002). Esse mineral pode atingir o tamanho silte após a combinação de alteração química e física (WRIGHT, 2007), sendo que sua solubilidade aumenta exponencialmente com a redução do tamanho dos cristais, o que explica sua ausência na argila fina (DREES et al, 1989).…”

“…Caulinita, outro mineral anteriormente descrito na fração silte de solos de manguezais (SOUZA JÚNIOR et al, 2008) SIMAS et al, 2005;MELO et al, 2001). Portanto, a possibilidade de herança das áreas fontes de sedimentos é completamente plausível.…”

“…Goethita e hematita são formados em condições de intenso intemperismo e podem se concentrar na fração silte dos solos mais evoluídos (POPPE et al, 1995;MUGGLER et al, 2001;OLIVEIRA et al, 2002). A presença de gibbsita também já foi relatada na fração silte de solos brasileiros desenvolvidos sobre o embasamento cristalino pré-cambriano (SIMAS et al, 2005).…”