Evaluation of climate change effects on future corn (Zea mays L.) yield in western Turkey



A comparative performance analysis was studied on well-known drought indices [Standardized Precipitation Index (SPI), Palmer Drought Severity Index (PDSI) and its moisture anomaly index (Orig-Z), self-calibrated Palmer Drought Severity Index (SC-PDSI) and its moisture anomaly index (SC-Z)] to determine the most appropriate index for assessing corn (Zea mays L.) yield in four crop regions (Aydın, Denizli, Afyon, Uşak) in western Turkey and to evaluate the vulnerability of corn production to climate change with future projections provided by the Hadley Centre for Climate Prediction and Research ENSEMBLES project (HadCM3Q0). A series of curvilinear regression-based crop-yield models were developed for each of the crop region based on the drought indices. The crop-yield model that performed best at high-drought risk years was the SC-PDSI in Aydın region and the PDSI in Denizli, Afyon and Uşak regions. The SC-PDSI index in Aydın region described 75.1% of the measured variability. The PDSI index in Denizli Ayfon and Uşak regions explained 69.8, 71.3 and 66.4% of the measured yield variability, respectively. The vulnerability of the corn yield to HadCM3Q0 projections was evaluated for Aydın and Afyon regions due to the resolution of the regional climate model. For the high-drought risk years, the expected decrease in corn yields was 2.1 ton ha−1 in Aydın region and 0.014 ton ha−1 for Afyon region. For the low drought risk years, the crop yield models predicted the expected decrease in corn yield as 0.104 ton ha−1 in Afyon region. However, there was a positive yield response by 0.022 ton ha−1 in Aydın region. Copyright © 2012 Royal Meteorological Society