Geoambientes de terra firme e várzea da região do Juruá, noroeste do Acre

• Ano de defesa: 2009
• Autor(a) principal: Portugal, Arley Figueiredo
• Orientador(a): Fontes, Luiz Eduardo Ferreira
• Banca de defesa: Santana, Rogério Mercandelle , Araújo, édson Alves de , Rocha, Genelício Crusoé
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Solos e Nutrição de Plantas
• Departamento: Fertilidade do solo e nutrição de plantas; Gênese, Morfologia e Classificação, Mineralogia, Química,
• País: BR
• Palavras-chave em Português: Acre; Desmatamento; Pastagem; Várzea do Juruá
• Palavras-chave em Inglês: Acre; Defforestation; Pastures; Várzea do Juruá
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/1595

There are two main environments in Acre State, with distinct geologic, geomorphologic, pedologic and fitossociologic characteristics and they are known as wetland which is marginal lands to Rivers, with periodic flooding and a dry land with no flood. In the State of Acre 88% of its land is cover by forest and from all deforested area 81% is used for extensive pastures. In this region, especially in the northwest, the wet and dry lands are little studied, which, justifies researches to better understanding those environments and evaluate the anthropogenic impacts. In this sense, the objective of this research is characterize physically, chemically and mineralogically the wet land environment, and also evaluate the physical, chemical and carbon storage disturbances in the northwest of Acre State. The research was executed in the Juruá micro region at the Cruzeiro do Sul and Rodrigues Alves counties. The region climate is characterized by high temperatures and pluviometric measures, with an annual precipitation average of 2.171mm. The climate is classified as Tropical Humid Awi (Koppen). In the wet land geoenvironment were evaluated 04 (four)Neossolo Flúvico Ta eutrófico profiles and 03 (three) Vertissolos Háplicos órtico profiles. In the dry land environment were studied the land use with native forest, 10 year old pasture, 20 year old pasture, and 10 year old forest regeneration, all of them in Argissolo Vermelho- amarelo distrófico. The soil profiles had a morphological description and were evaluated its physical, chemical, mineralogical and biological parameters. In the wet land environment there was a domination of sand fraction in every land use and different depths evaluated. The removal of native forest and pasture introduction caused a negative impact over the physic properties of the soil and carbon storage in the soil. There was high values of soil density and soil resistance to penetration and porosity (macroporosity higher than 145 µm) and hydraulic conductivity, although, there were not found disturbances in the aggregated stability and available water. The total carbon and nitrogen storages, fulvic acids, humic acids and humin, as well as the microbiological carbon were reduced in the pasture. The forest regeneration area showed partial recovering in the soil physic properties, as well as in the microbiological carbon soil storage, showing that the non-use and forest regeneration contributes to positive effects to those areas rehabilitation. In the wet land area can be observed that the silted soils are dominant with an absence of thick sand and high water dispersed clay, due to a high level of magnesium. The soils also showed high pH and nutrient levels, especially Ca2+, but the levels of carbon were much reduced. In the clay and silt fraction of Neossolos Flúvicos and Vertissolos, the predominant are: primary minerals, mica, feldspar, olivine and plagioclase, besides the significant content of smectite, vermiculite, ilite, kaolinite and quartz, this reflects the Andes geological nature, where Juruá River has its spring. There was a soft sand fraction domination, which, is formed basically by minerals as quartz, feldspar, plagioclase and rutile. The soils showed high levels of SiO2 and low levels of Fe2O3, besides of having high Feo/Fed ratio, indicating low paedogenesis of this soils and less crystallized iron presence. The Neossolos Flúvicos showed good porosity, although with low levels of macroporosity and high levels of microporosity, which leads to a reduced hydraulic conductivity and good water retention capacity. Besides having a low macroporosity, the soil resistance to penetration values were low, which indicates that there is no physical barrier for root growing. The soil density values for Vertissolos were high, which indicates that can be a physical barrier for root growing.