Geoambientes, estoques de carbono e termodegradação da matéria orgânica de solos da Área de Proteção Ambiental Estadual Cachoeira das Andorinhas, Ouro Preto, Minas Gerais

• Autor(a) principal: Guedes, ítalo Moraes Rocha
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1591
• topic: Geomorfologia; Estoque de carbono; Resistência à termodegradação; Geomorphology; Carbon stocks; Thermodegradation resistance; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

The aims of this work were to generate information on the physical environment followed by the production of digital thematic maps, estimate surface and subsurface soil carbon stocks (CS) of different soil classes in mountainous environments from Cachoeira das Andorinhas Environment Preservation Area in Minas Gerais state, Brazil, calculate the phytomass CS/soil CS ratio and to evaluate the resistance of organic matter from selected soil horizons to heat treatments. Soil chemical and physical analysis were proceeded according to Embrapa (1997). Soil carbon stocks were estimated from organic matter data of selected soil profiles. Phytomass carbon stocks were estimated from values collected in scientific literature. Heat treatments, or thermodegradation, consisted of submitting soil samples to the temperatures of 100, 200, 300, 400 and 500°C for 2h in a digital muffle furnace. Geologically, most of the area is on phyllite material surrounded by quartzitic mountains and structural escarpments. The main geomorphological unit are the Alto Rio das Velhas convex hills, covering 52.4% of the área. More than 50% of the Environmental Protection Area is on dystrophic Haplic Cambisols. Except in the Melanic Gleysol and in the Litholic Neosol, higher carbon stocks were found in soil subsurface horizons. The estimated carbon stocking service values were high, ranging from US$808.51 ha-1 for Melanic Gleysol to US$3,626.50 ha- 1 for the Red-Yellow Latosol. The highest values for phytomass CS/soil CS ratio were observed in Haplic Cambisols and Litholic Neosols, while the lowest values were found in Ferocarbic Spodosols and Humic Cambisols and Red-Yellow Latosols displayed intermediate values. Temperature increase made soil organic carbon levels decrease in all soil horizons evaluated. Organic matter stored in the Bh horizon of the Spodosol was more stable to heat treatments up to the 400° C temperature. Superficial horizons organic matter was more stable in Melanic Gleysol and Humic Cambisol. Soils in altitudes higher than 1200 m are more efficient in sequestering carbon. Subsurface carbon stocks in Red- Yellow Latosols are twice as large as surface stocks. Estimated organic carbon stock service values were higher in Latosols than in the other soils. Hydromorphic and humic soils, rich in fibric organic matter are highly resistant to thermodegradation. Spodic horizons store organic carbon highly resistant to thermodegradation and this organic material is possibly the most recalcitrant in mountainous environments.