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Öğe Enhanced Growth Rate and Reduced Water Demand of Crop Due to Climate Change in the Eastern Mediterranean Region(Springer International Publishing Ag, 2019) Ben-Asher, Jiftah; Yano, Tomohisa; Aydin, Mehmet; Garcia y Garcia, AxelThe specific objectives of this study were to: (a) test the reliability of a regional climate model (RCM) as a tool for climate change projection in the Eastern Mediterranean, (b) compare the observed yield variables of maize and wheat in the region with results of two crop models, (c) compare the models DSSAT and SWAP and (d) use DSSAT and SWAP to generate future productivity of wheat and maize under the A2 global warming scenario. Reference evapotranspiration was highly correlated with the models with average r(2) = 0.98 and a unit slope. The two models accurately predicted observed dry mass production (DMP) and leaf area index (LAI) of wheat and maize. The correlations strengthen the legitimacy of DSSAT, SWAP and RCM to serve as predicting models for future climate change on a regional scale. A simulation was carried out to describe the effects of climate change on crop growth and irrigation water requirements for a wheat-maize-wheat cropping sequence. Climate change scenarios were projected using data of three general circulation models (CGCM2, ECHAM4 and MRI) for the period of 1990-2100 and one RCM for the period of 2070-2079. Daily RCM data were consistent with actual meteorological data in the region and therefore were used for computations of present and future water balance and crop development. Predictions derived from the models about changes in irrigation and crop growth covered the period of 2070-2079 relative to a baseline period of 1994-2003. The effects of climate change on wheat and maize water requirements and yields were predicted using the detailed crop growth subroutine of the DSSAT (Decision Support System for Agrotechnology Transfer) and SWAP (Soil-Water-Atmosphere-Plant) models. Precipitation was projected to decrease by about 163, 163 and 105 mm during the period of 1990-2100 under the A2 scenario of the CGCM2, ECHAM4 and MRI models respectively (an average of about 1.3 mm/year). The models projected a temperature rise of 4.3, 5.3 and 3.1 degrees C, by the year 2100. An increase in temperature may result in a higher evaporative demand of the atmosphere under combined doubling CO2 concentration and temperature rise by about 2 degrees C for the period of 2070-2079. The temperature rise accelerated crop development and shortened the growing period by a maximum of thirteen days for wheat and nine days for maize during the period 2070-2079. When yield and available water (rain + applied irrigation) were normalised by extension of the growing period with respect to the baselines years, DMP of maize increased by 1-3 ton ha(-1) and that of wheat by 3-4 ton ha(-1). Consequently, water use efficiency (WUE) increased for both crops. It was concluded, therefore, that the effect of increased temperature and doubling CO2 on agro-productivity may be positive. This positive effect can be explained if elevated temperature meets the optimal level of a crop response to temperature. Effects of elevated CO2 on crop tolerance to water stress may counteract the expected negative effects of rising temperature. Increased atmospheric CO2 levels have important physiological effects on crops such as the increase in photosynthetic rate, which is associated with higher yield and WUE, at least for some cereal crops in the Eastern Mediterranean.Öğe Impact of climate change on irrigation demand and crop growth in a Mediterranean environment of Turkey(Mdpi, 2007) Yano, Tomohisa; Aydin, Mehmet; Haraguchi, TomokazuA simulation study was carried out to describe effects of climate change on crop growth and irrigation water demand for a wheat-maize cropping sequence in a Mediterranean environment of Turkey. Climate change scenarios were projected using data of the three general circulation models-GCMs (CGCM2, ECHAM4 and MRI)-for the period of 1990 to 2100 and one regional climate model-RCM-for the period of 2070 to 2079. Potential impacts of climate change based on GCMs data were estimated for the A2 scenario in the Special Report on Emission Scenarios (SRES). The forcing data for the boundary condition of the RCM were given by the MRI model. Daily CGCM2 and RCM data were used for computations of water balance and crop development. Predictions derived from the models about changes in irrigation and crop growth in this study covered the period of 2070 to 2079 relative to the baseline period of 1994 to 2003. The effects of climate change on water demand and on wheat and maize yields were predicted using the detailed crop growth subroutine of the SWAP (Soil-Water-Atmosphere-Plant) model. Precipitation was projected to decrease by about 163, 163 and 105 mm during the period of 1990 to 2100 under the A2 scenario of the CGCM2, ECHAM4 and MRI models, respectively. The CGCM2, ECHAM4 and MRI models projected a temperature rise of 4.3, 5.3 and 3.1 degrees C, respectively by 2100. An increase in temperature may result in a higher evaporative demand of the atmosphere. However, actual evapotranspiration (ETa) from wheat cropland under a doubling CO2 concentration for the period of 2070 to 2079 was predicted to decrease by about 28 and 8% relative to the baseline period based on the CGCM2 and RCM data, respectively. According to these models, irrigation demand by wheat would be higher for the same period due to a decrease in precipitation. Both ETa and irrigation water for maize cropland were projected to decrease by 24 and 15% according to the CGCM2, and 28 and 22% according to the RCM, respectively. The temperature rise accelerated crop development but shortened the growing period by 24 days for wheat and 9 days for maize according to the CGCM2 data. The shortened growth duration with a higher temperature reduced the biomass accumulation of both crops regardless of CO2-fertilization effect. With the combined effect of CO2-fertilization and increased temperature, the CGCM2 and RCM projections resulted in an increase by 16 and 36% in grain yield of wheat and a decrease by about 25% and an increase by 3% in maize yield, respectively.Öğe Implications of climate change for evaporation from bare soils in a Mediterranean environment(Springer, 2008) Aydin, Mehmet; Yano, Tomohisa; Evrendilek, Fatih; Uygur, VeliThe purpose of this study was to predict quantitative changes in evaporation from bare soils in the Mediterranean climate region of Turkey in response to the projections of a regional climate model developed in Japan (hereafter RCM). Daily RCM data for the estimation of reference evapotranspiration (ETr) and soil evaporation were obtained for the periods of 1994-2003 and 2070-2079. Potential evaporation (E-p) from bare soils was calculated using the Penman-Monteith equation with a surface resistance of zero. Simulation of actual soil evaporation (E-a) was carried out using Aydin model (Aydin et al., Ecological Modelling 182:91-105, 2005) combined with Aydin and Uygur (2006, A model for estimating soil water potential of bare fields. In Proceedings of the 18th International Soil Meeting (ISM) on Soils Sustaining Life on Earth, Managing Soil and Technology, Sanliurfa, 477-480pp.) model of predicting soil water potential at the top surface layer of a bare soil, after performances of Aydin model (R-2 = 94.0%) and Aydin and Uygur model (R-2 = 97.6) were tested. The latter model is based on the relations among potential soil evaporation, hydraulic diffusivity, and soil wetness, with some simplified assumptions. Input parameters of the model are simple and easily obtainable such as climatic parameters used to compute the potential soil evaporation, average diffusivity for the drying soil, and volumetric water content at field capacity. The combination of Aydin and Aydin and Uygur models appeared to be useful in estimating water potential of soils and E-a from bare soils, with only a few parameters. Unlike ETr and E-p projected to increase by 92 and 69 mm (equivalent to 8.0 and 7.3% increases) due to the elevated evaporative demand of the atmosphere, respectively, E-a from bare soils is projected to reduce by 50 mm (equivalent to a 16.5% decrease) in response to a decrease in rainfall by 46% in the Mediterranean region of Turkey by the 2070s predicted by RCM, and consequently, to decreased soil wetness in the future.Öğe Interactive Effects of Elevated CO2 and Climate Change on Wheat Production in the Mediterranean Region(Springer International Publishing Ag, 2019) Kapur, Burcak; Aydin, Mehmet; Yano, Tomohisa; Koc, Mujde; Barutcular, CelaleddinGlobal climate change could be harmful to agriculture. In particular, water availability and irrigation development under changed climatic conditions already pose a growing problem for crop production in the Mediterranean region. Wheat is the major significant crop in terms of food security. Therefore, in relation to these issues, this review gives an overview of climate change effects on wheat production in the Mediterranean environment of Turkey. Future climate data generated by a general circulation model (e.g., CGCM2) and regional climate models (e.g., RCM/MRI, CCSR-NIES and TERCH-RAMS) have been used to quantify the wheat growth and the soil-water-balance around the Eastern Mediterranean region of Turkey. The effects of climate change on the water demand and yield of wheat were predicted using the detailed crop growth subroutine of the SWAP (Soil-Water-Atmosphere-Plant). The Soil evaporation was estimated using the E-DiGOR (Evaporation and Drainage investigations at Ground of Ordinary Rainfed-areas) model. This review revealed that the changes in climatic conditions and CO2 concentration have caused parallel changes in the wheat yield. A close correspondence between measured and simulated yield data was obtained. The grain yield increased by about 24.7% (measured) and 21.9% (modelled) under a two-fold CO2 concentration and the current climatic conditions. However, this increase in the yield was counteracted by a temperature rise of 3 degrees C. Wheat biomass decreases under the future climatic conditions and the enhanced CO2 concentration, regardless of the model used. Without CO2 effects, grain yield also decreases for all the models. By contrast, the combined impact of elevated CO2 and increased temperature on grain yield of wheat was positive, but varied with the climatic models. Among the models, the CCSR-NIES and TERCH-RAMS denote the highest (24.9%) and lowest (6.3%) increases in grain yield respectively. The duration of the regular crop-growing season for wheat was 24, 21, and 27 days shorter as calculated for the future, mainly caused by the projected air temperature rise of 2.2, 2.4, and 3 degrees C for a growing period by the 2070s for CGCM2, CCSR-NIES and TERCH-RAMS respectively. The experimental results show large increases in the water use efficiency of wheat, due to the increases in CO2 concentration and air temperature. Despite the increased evaporative demand of the atmosphere, the increases in water use efficiency can be attributed to the shorter growing days and a reduction in the transpiration due to stomata closure. Unlike reference evapotranspiration and potential soil evaporation, actual evaporation from bare soils was estimated to reduce by 16.5% in response to a decrease in rainfall and consequently soil wetness in the future, regardless of the increases in the evaporative demand. It can be concluded that to maintain wheat production in the future, the water stress must be managed by proper irrigation management techniques.Öğe The use of aridity index to assess implications of climatic change for land cover in Turkey(2009) Önder, Derya; Aydın, Mehmet; Berberoğlu, Süha; Önder, Sermet; Yano, TomohisaThis study was carried out to determine the impacts of climate change on aridity and land cover in Turkey. Data for future (2070s) climate change, according to present conditions (1990s), were estimated from the prediction results of a regional climate model (RCM). The RCM, which was developed in Japan, is based on the MRI model. The potential impacts of climate change were estimated according to the A2 scenario of Special Report on Emissions Scenarios (SRES). Aridity index, the ratio of precipitation to potential evapotranspiration, was computed by using measured data for the present condition and estimated data by the RCM for the future years. Changes in aridity were evaluated by comparing the current and future index values. Aridity variables were interpolated to determine the spatial distribution by means of geostatistical methods. Land cover was modelled and mapped by using the present and future aridity index data. In the southern regions of Turkey, especially along Mediterranean coasts, projected precipitation for 2070s will be 29.6% less than the present. On the contrary, an increase (by 22.0%) in precipitation was projected along the coast of Black Sea. The model predicted that the temperature might increase by 2.8-5.5 °C in the different regions of the country. This increase in temperature could result in higher evaporative demand of the atmosphere in the future (on the average 18.4 and 22.2% in the Mediterranean and Black Sea coastal regions, respectively and 17.8% in the whole country). Thus, an increase in aridity was foreseen for the whole Turkey except the north-eastern part. A conversion of deciduous broadleaf forest to evergreen needle-leaf forest is predicted in the northern coastal areas when we compare the future land cover with the present situation. The mixed forest vegetation could spread in the interior parts of East Anatolia and the north-western part of the country in the future.
