Potential effects of global climatic change on the phenology and yield of maize in venezuela |
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Authors: | Carlos E. Maytín Miguel F. Acevedo Ramón Jaimez Rigoberto Andressen Mark A. Harwell Alan Robock Aura Azócar |
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Affiliation: | (1) Centro de Investigaciones Ecológicas de los Andes Tropicales (CIELAT), Facultad de Ciencias, Universidad de Los Andes, 5101 Mérida, Venezuela;(2) Institute of Applied Sciences and Department of Geography, University of North Texas, 76203 Denton, TX, USA;(3) Centro de Investigación y Proyectos en Simulación y Modelos (CESIMO), Facultad de Ingeniería, Universidad de Los Andes, 5101 Mérida, Venezuela;(4) Centro de Estudios Avanzados del Clima Tropical (CEACT), Ministerio del Ambiente y de los Recursos Naturales Renovables and Universidad de Los Andes, Mérida, Venezuela;(5) Rosenstiel School of Marine and Atmospheric Science, University of Miami, 33149 Miami, FL, USA;(6) Department of Meteorology, University of Maryland, 20742 College Park, MD, USA |
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Abstract: | Simulated impacts of global and regional climate change, induced by an enhanced greenhouse effect and by Amazonian deforestation, on the phenology and yield of two grain corn cultivars in Venezuela (CENIAP PB-8 and OBREGON) are reported. Three sites were selected:Turén, Barinas andYaritagua, representing two important agricultural regions in the country. The CERES-Maize model, a mechanistic process-based model, in theDecision Support System for Agrotechnology Transfer (DSSAT) was used for the crop simulations. These simulations assume non-limiting nutrients, no pest damage and no damage from excess water; therefore, the results indicate only the difference between baseline and perturbed climatic conditions, when other conditions remain the same. Four greenhouse-induced global climate change scenarios, covering different sensitivity levels, and one deforestation-induced regional climate change scenario were used. The greenhouse scenarios assume increased air temperature, increased rainfall and decreased incoming solar radiation, as derived from atmospheric GCMs for doubled CO2 conditions. The deforestation scenarios assume increased air temperature, increased incoming solar radiation and decreased rainfall, as predicted by coupled atmosphere-biosphere models for extensive deforestation of a portion of the Amazon basin. Two baseline climate years for each site were selected, one year with average precipitation and another with lower than average rainfall. Scenarios associated with the greenhouse effect cause a decrease in yield of both cultivars at all three sites, while the deforestation scenarios produce small changes. Sensitivity tests revealed the reasons for these responses. Increasing temperatures, especially daily maximum temperatures, reduce yield by reducing the duration of the phenological phases of both cultivars, as expected from CERES-Maize. The reduction of the duration of the kernel filling phase has the largest effect on yield. Increases of precipitation associated with greenhouse warming have no effects on yield, because these sites already have adequate precipitation; however, the crop model used here does not simulate potential negative effects of excess water, which could have important consequences in terms of soil erosion and nutrient leaching. Increases in solar radiation increased yields, according to the non-saturating light response of the photosynthesis rate of a C4 plant like corn, compensating for reduced yields from increased temperatures in deforestation scenarios. In the greenhouse scenarios, reduced insolation (due to increased cloud cover) and increased temperatures combine to reduce yields; a combination of temperature increase with a reduction in solar radiation produces fewer and lighter kernels.A report of thePAN-EARTH Project, Venezuela Case Study. |
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