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Universidade Federal do Ceará (2015)

Dynamics of soil organic matter in managed areas and preserved in flona Araripe


Titre : Dynamics of soil organic matter in managed areas and preserved in flona Araripe



Université de soutenance : Universidade Federal do Ceará

Grade : Doutorado 2015

The current concern about global climate change resulting from the increase in greenhouse gas concentrations in the atmosphere, especially CO2, has aroused the attention of the scientific community to the biogeochemical cycling of carbon. This study performed a theoretical and experimental analysis of the dynamics of soil organic matter in an area subjected to clear cutting of native vegetation to understand the influence of changes in physical, chemical and biological soil properties on sequestration and/or emission of atmospheric CO2. The study was conducted at the Araripe National Forest and at the Unit of Forest Management of the Farm Pau d’Arco and Bonfim. In the area of sustainable management, there were selected 5 out of 22 plots existing and an area of about 200 m2 in the Environmental Reserve and FLONA- Araripe. In each area, we selected five random sites, at the layers 0-10, and 10-20 and 020 cm from 2012 2013 and 2014 amounting to 6 collections. The following analyses were performed : physical, chemical, mineralogical and microbiological. Climate data used in the Application Century, referring to the monthly rainfall, were obtained at the weather station of FLONA- Araripe. It was applied analysis of variance, with 6 replications and 7 treatments at the layers : 0-10, 10-20 and 0-20 cm. Mean values of the different layers were compared by Tukey’s test at 5% probability, in the software Statistical Analysis Systems, using the factorial analysis by the main components method. For the theoretical study, we used the sub-model of the dynamics of soil organic matter available at Century 4.0. The accuracy of the simulations was verified by the correlation coefficient between simulated and observed data, calculated by Microsoft Excel data analysis tool. The areas showed predominance of mineral kaolinite and iron and aluminum oxides, thus favoring the protection of organic material. At FLONA- Araripe, we found the largest contents of TCO, Clabile, C storage, CMIC, CMOL and lower RBS and qCO2, the opposite occurred for UMF. Principal component analysis evidenced that from 8 attributes obtained from the commonality analysis only 5 are required to understand the dynamics of MOS, resulting in two factors : TCO, Clabile and IMC and the NT and CMIC. In the calibration, the appropriate PRDX was (140 and 11 g C m-2) respectively for FLONA and UMF. The fits of the carbon decay constants in both areas (K) FLONA- Araripe DEC4 (0.00402) DEC5 (0.22500) and DEC3.2 (6.5000) produced the following errors (0.04, 3.7, 2.3%). The correction factors A* were (0.89) for carbon ative (CA) and carbon passive (CP) and (1.12) for carbon leve (CL). The input variables maximum and minimum temperatures were the most sensitive. The validation of the application in UMF elucidated that the DEC4 there was no reduction in C in the first two months, being stable at four years. DEC5 reductions in C in the first months of management and recovery 7 years and the DEC 3.2 reductions C in the first months of management and stable 5 years. In this sense, the use of the application with necessary fits in decay constants (DEC4, DEC5 and DEC3.2) responds satisfactorily to the carbon accumulated in the soil according to the quality and quantity elucidating the dynamics of SOM influences the CO2 sequestration.

Mots clés :  : Century Model. Forest Management. Soil. Semi-arid. Forest Modelo Century. Manejo Florestal.Solo. Semiárido. Floresta

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Page publiée le 3 septembre 2017, mise à jour le 12 mars 2019