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Accueil du site → Doctorat → Brésil → Adaptação do modelo Century para simulação da produtividade de biomassa e ciclagem do carbono e nitrogênio em áreas de caatinga

Universidade Federal de Pernambuco (UFPE) 2015

Adaptação do modelo Century para simulação da produtividade de biomassa e ciclagem do carbono e nitrogênio em áreas de caatinga

ALTHOFF, Tiago Diniz

Titre : Adaptação do modelo Century para simulação da produtividade de biomassa e ciclagem do carbono e nitrogênio em áreas de caatinga

Auteur : ALTHOFF, Tiago Diniz

Université de soutenance : Universidade Federal de Pernambuco (UFPE)

Grade : Doutor 2015

Résumé
Brazilian semiarid region is characterized by spatial and temporal variability of rainfall, combined with high temperatures, which is to increase evapotranspiration and to form different types of soils originating different forest vegetation types compositions in the region. According to the current climate modeling, the Caatinga is among the most vulnerable to possible climate change scenario. Such changes can alter the biogeochemical cycling and to influence the dynamics of carbon (C) and nitrogen (N) in vegetation and soils. In addition to climate vulnerability, the removal of wood for use as an energy source and the use of native vegetation as pasture for ruminants are anthropic disturbance practices in the region. With this complexity of ecosystems in the Caatinga makes it difficult to design and monitoring of sustainable systems of land use in the region from observations and experimental studies. In this sense, the mathematical models simulating the biogeochemical cycling can contribute to a better understanding of these processes. Among the various simulation models of biogeochemical cycling in terrestrial ecosystems, the Century has been successfully used to simulate the dynamics of C and N, P and S in different agro-ecosystems in the world. Thus, the objective of this study was to adapt the Century model to simulate the flow and C and N stocks in soil and native vegetation of the Caatinga submitted to differents forest cutting plans under the A1B climate scenario until year 2100. The data used (vegetation, soil and climate) were obtained in field plots in the cities of Santa Teresinha-PB (calibration) and Serra Negra do Norte-RN (validation). Predominant soil areas was the Litholic Neosol the preserved plots without clearcutting or significant human disturbance for at least the past 50 years and in the process of natural regeneration of 15 and 18 years of vegetation. With the estimated native forest biomass was considered 45% of C. Plans cuts chosen for simulation were from observational data of the wood removed (clear-cutting), whether or not the waste burning. In the validation phase for plots in Serra Negra do Norte, RN, the simulated values of C stocks of aboveground biomass of tree in conservation areas (20.6 Mg ha-1) coincided with the average values observed in the field (20.3 Mg ha-1), which validated the model satisfactorily. The model also simulated adequately the dynamics of C and N between the vegetation and the soil after the plans cuts over 15 to 18 years. With the validated model, we evaluated the impact of climate scenarios on flows and C soil-plant stocks in different periods (10, 15 and 20) clear cut (CR) with (CQ) and unburned (SQ). The climate scenario used was the SRES A1B, designed by Eta/CPTEC model for the periods 2010-2040, 2041-2070 and 2071-2100, comprising members LOW, MIDI, and HIGH revealing the extent of simulations A1B scenario. All scenarios were compared with the historical climate, designed in future intervals evaluated as reference of climate effects on the periods of adopted cutting plane. In 2100, the reductions in tree biomass accumulation in both treatments (CR-CQ and SQ) reached close to 50% and 15% of COS confronted to the historic climate scenario. Therefore, a better understanding of the functioning of forest ecosystems can contrib

Mots Clés : Dry forest, soil, climate, modeling

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Page publiée le 23 août 2017