Estado-da-arte da simulação da taxa de fixação de carbono de ecossistemas tropicais

Abstract

RESUMOEste trabalho avalia o estado-da-arte de modelos de simulação da taxa de fixação de carbono, ou produção primária liquida (NPP), de ecossistemas tropicais em duas configurações diagnósticas (simulação em sítios micrometeorológicos e simulação forçada por dados climáticos e por produtos de sensoriamento remoto) e uma prognóstica (simulação por um modelo acoplado clima-vegetação). Os resultados indicam que os modelos de estimativa de NPP atingiram capacidade de fazer estimativas não-viesadas de valores médios regionais de NPP, tanto no modo diagnóstico, quanto no modo prognóstico, com erros inferiores a 5%, enquanto o valor esperado do erro em cada sítio é inferior a 10% no modo diagnóstico e inferior a 20% no modo prognóstico. Os modelos estado-da-arte são capazes de monitorar a taxa de fixação de carbono por ecossistemas tropicais de maneira rotineira, sendo esperados baixos erros para essas estimativas. Palavras-chave: Produção Primária Líquida, Modelagem, Florestas Tropicais. ABSTRACT: STATE-OF-THE-ART OF THE SIMULATION OF CARBON FIXATION RATES BY TROPICAL ECOSYSTEMSThis work evaluates the state-of-the-art of the simulation of carbon fixation rates, or net primary production (NPP) by tropical ecosystems in two diagnostic configurations (simulation at micrometeorological sites and simulation forced by climate datasets and remote sensing products) and one prognostic (simulation by a coupled climate-biosphere model). The results indicate that the NPP simulation models are capable of unbiased estimates of average regional values of NPP, both in diagnostic and in prognostic mode, with errors smaller than 5%, while the expected value of the error in each site is smaller than 10% in the diagnostic mode and smaller than 20% in the prognostic mode. State-of-the-art models are capable of routinely monitoring the net primary production of tropical ecosystems, with low errors expected for these estimates. Keywords: Net Primary Production, Modeling, Tropical Forests INTRODUÇÃOO cenário mais provável nas próximas décadas apresenta fortes modificações no meio ambiente global, incluindo aumento da concentração atmosférica de CO 2 e outros gasestraço, mudanças climáticas e intensificação dos impactos causados pela ação do homem. É esperado que essas mudanças causem importantes modificações na composição, estrutura e distribuição dos ecossistemas pelo planeta. Desta forma, um monitoramento preciso das mudanças na biosfera terrestre tem se tornado extremamente importante, pois detectar a variabilidade interanual e as tendências de longo prazo na estrutura dos ecossistemas permitirá identificar antecipadamente mudanças na biosfera que, do contrário, passariam despercebidas até o início de uma transformação do bioma.Além do monitoramento da biosfera, também é importante ter capacidade preditiva do seu estado futuro. A vegetação é o espelho do clima, com o qual interage de

Assessing Carbon Sequestraded in Brazilian Northeastern Biomes Under Enso Events

“…These results are consistent with those of Costa et al (2009), which obtained values from 1050 to 1360 gC. Costa et al (2009) performed their analyzes for isolated points in the states of Pará, Amazonas and Acre, while the results presented in the present study are for the Amazon Rainforest area of the NEB.…”

“…These results are consistent with those of Costa et al (2009), which obtained values from 1050 to 1360 gC. Costa et al (2009) performed their analyzes for isolated points in the states of Pará, Amazonas and Acre, while the results presented in the present study are for the Amazon Rainforest area of the NEB. It was seen a variability in this biome among the years of absence of ENSO episodes, especially in the years 1985/86 and 1996/97, since there was an increase in the area of high values of sequestration, reaching the eastern part of the Caatinga.…”

“…They observed a higher value of NPP in La Niña years, but did not do any statistical test, since they had only one year of La Niña, one of El Niño and two neutrals. It is noteworthy still that Costa et al (2009) making a NPP analysis for the Amazon Rainforest also obtained results similar to those of Potter et al (2009) and those obtained in the present study.…”

“…When performing a statistical analysis of comparison of means, it is observed that the average carbon absorption by Atlantic Forest during the periods of events: La Niña, El Niño and neutral are not statistically different, since the Student's t test for differences of means values did not present statistical significance. Costa et al (2009) obtained NPP of 1366 gC.m -2 .yr -1 in Teixeira de Freitas, Bahia State, in an Atlantic Forest area, in the year 2006, that is, a value similar to that obtained in this research for the area of Teixeira de Freitas (Figures 5 to 7).…”

Energy and mass transfer parameters in a brazilian semi-arid ecosystem under different thermohydrological conditions

“…Even the "Caatinga" ecosystem being heterogeneous both vertically and horizontally, it has an expressive potential for development of rural productivity activities, despite the low amounts of precipitation in the Brazilian semi-arid region (Costa et al, 2009). Oyama and Nobre (2004) demonstrated, however, through global circulation models that changes in this natural ecosystem have caused desertification, demanding more study about the effect of these changes on the energy and water balances.…”