Banca de DEFESA: EDUARDO CARVALHO DA SILVA NETO
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : EDUARDO CARVALHO DA SILVA NETO
DATE: 23/08/2022
TIME: 08:30
LOCAL: Ambiente Virtual
TITLE:
Organic soils in high montane environments of southeastern Brazil: formation, classification, and relationships with the vegetation history
KEY WORDS:
Histosols. Soil-landscape relationship. Climate changes. Quaternary.
PAGES: 121
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Gênese, Morfologia e Classificação dos Solos
SUMMARY:
Upland organic soils develop under unique highland environments in contrast to the wetland organic soils, and can be considered as endemic soils, i.e. soils that are restricted to a particular geographic area based on a unique combination of soil-forming factors. In this contribution, our purpose is to improve the pedological knowledge of the Brazilian highlands, focusing on well-drained organic soils. We report the occurrence of organic soils with andic properties (non-allophanic) in the highlands from southeastern Brazil (Serra da Mantiqueira). The cold climate and high cloudiness of these high-altitude areas favor the formation of a constantly humid environment and the acid weathering of the source material, accumulation of organic matter in the soil, and its stabilization by the formation of organo-metallic complexes, especially Al-humus. We document and discuss morphological, physical, and chemical characteristics of 14 soil profiles in the Serra da Mantiqueira region, as well as the occurrence of andic properties (non-allophanic) in some of them. The objective was to propose a general scheme for the formation of these soils, based on classical soil analysis (morphological, physical, and chemical) in combination with specific analysis for paleoenvironmental reconstruction in well-drained soils (phytoliths, δ13C isotopic composition and 14C datings). Upland organic soils (Organossolos Fólicos) in the highland environments of Serra da Mantiqueira are formed by accumulation of litter (plant residues) in two pedoenvironments: (1) directly on bedrock in the high-elevation grasslands, by the processes of addition and transformation of the litter, which constitute the parent material from these soils; and (2) in upper-montane forests, with organic horizons formed under mineral horizons. In both conditions, the cold and humid climate and vegetation (organisms) are the main soil-forming factors, not only reducing the decomposition of organic matter, but influencing the physical and chemical properties of the soils. The cold and humid climate of the high montane environments in southeastern Brazil results in soils with andic properties (non-allophanic). Based on phytolith records, δ13C, C3 and C4 plant-derived carbon stocks, and 14C datings, it was possible to infer four environmental conditions: Phase I (before ~18,9k yr BP), climate cooler and drier than present, with predominance of subtropical grassland vegetation and fire events; Phase II (~18,9k yr BP to ~11,1k yr BP), slight increase in humidity, decrease in fire events and expansion of forest formations, with rare presence of Araucaria angustifolia; Phase III (from ~11,1k years BP) increase in humidity, establishment of current conditions (cold and humid climate, typical of southeastern Brazilian highlands), and marked presence of Araucaria in upper-montane forests; Phase IV (present) environmental changes related to increased fire events, reduction of Araucaria and increase of Bambusoid, Arecaceae and C4 plants, possibly resulted from human activities.
BANKING MEMBERS:
Presidente - 1060711 - MARCOS GERVASIO PEREIRA
Externo à Instituição - JOSÉ JOÃO LELIS LEAL DE SOUZA
Externa à Instituição - INGRID HORÁK TERRA
Externo à Instituição - FABIO SOARES DE OLIVEIRA - UFMG
Externo à Instituição - GUSTAVO SOUZA VALLADARES - UFPI