G. M. Bettiol

Mudanças Climáticas Globais e a Pecuária: Cenários Futuros para o Semiárido Brasileiro (Global Climatic Changes and Animal Production: Future Scenarios for the Brazilian Tropical Semiarid)

Os sistemas de producao animal no Semiarido brasileiro podem ser vulneraveis as mudancas climaticas. Cenarios futuros para a producao de Brachiaria brizantha, Panicum maximum, Cenchrus ciliaris e Opuntia ficus indica foram analisados para a identificacao de areas mais vulneraveis. A partir dos modelos ja disponiveis, foram identificadas algumas areas de maior vulnerabilidade, o que possibilitou a indicacao de alternativas de adaptacao dos sistemas de producao para mitigacao de possiveis impactos negativos das mudancas climaticas globais sobre a producao animal do Semiarido brasileiro. O desenvolvimento de tecnicas para o uso sustentavel da Caatinga como pasto nativo contribuira para reduzir a degradacao deste bioma e os riscos de desertificacao da regiao. Novas variedades de plantas forrageiras, tanto de exoticas quanto de especies nativas, melhor adaptadas para as condicoes de cenarios climaticos futuros poderao ser desenvolvidos atraves do melhoramento vegetal. O uso de irrigacao de pastagens e o aproveitamento de co-produtos na alimentacao dos animais contribuirao para o aumento de produtividade e para a reducao da pressao sobre a vegetacao nativa. Diversos grupos de pesquisa tem desenvolvido modelos melhores para projecao regionalizada de chuva e de temperatura. O desenvolvimento desses modelos permitira uma investigacao mais precisa dos possiveis impactos das mudancas climaticas globais sobre a pecuaria no semiarido brasileiro.

Mudanças climáticas e cenários futuros para a produção de capim‑marandu no Estado de São Paulo

The objective of this work was to analyze future scenarios for palisade grass yield subjected to climate change for the state of Sao Paulo, Brazil. An empirical crop model was used to estimate yields, according to growing degree-days adjusted by one drought attenuation factor. Climate data from 1963 to 2009 of 23 meteorological stations were used for current climate conditions. Downscaled outputs of two general circulation models were used to project future climate for the 2013-2040 and 2043-2070 periods, considering two contrasting scenarios of temperature and atmospheric CO2 concentration increase (high and low). Annual dry matter yield should be from 14 to 42% higher than the current one, depending on the evaluated scenario. Yield variation between seasons (seasonality) and years is expected to increase. The increase of dry matter accumulation will be higher in the rainy season than in the dry season, and this result is more evident for soils with low-water storage capacity. The results varied significantly between regions ( 60%). Despite their higher climate potential, warmer regions will probably have a lower increase in future forage production.

Climatic risk zoning for corn and palisade grass (Brachiaria brizantha cv: Marandu) cultivated in integrated crop-livestock systems in São Paulo state, Brazil

Climatic risk zoning allows the identification of areas of low risk of reduced crop productivity due to climatic events. In Brazil, losses to agriculture due to climate are mainly caused by drought. The objective of this research was to determine areas of low climatic risk for corn and palisade grass cultivated in integrated crop-livestock systems in Sao Paulo state. Corn varieties characterized by a 120-day growing cycle and soil with three different water holding capacities (sandy, medium and clayey soils) were considered. A daily water balance model was used to simulate planting dates between September and December. The water requirement satisfaction index (WRSI) was calculated for critical phenological phases of both cultures (germination, emergence and tillering of palisade grass and flowering and grain filling of corn). The WRSI values, calculated for a minimum frequency of 80%, were located spatially using the SPRING v. 5.1 geographic information system and the most favorable periods for sowing in different areas were determined. The results showed that there are areas of low climatic risk for cultivation of corn and palisade grass in integrated crop-livestock production systems in Sao Paulo state. Although climatic risk in these areas also depends on soil type, the most favorable period for planting is between October and November.