Simulation Of The Impact Of Climate Change On Maize Production In The Middle Arid Region In Ningxia

According to the Fifth Assessment Report of IPCC:the global average surface temperature is liner upward trend, and increases by 0.85℃; and with global warming, the average temperature near the surface of China increases rapidly by 0.5-0.8℃ since the last 100a. Climate change impacts on agricultural production, especially in the Northwest China where ecological environment is fragile. As maize is one of the three main crops in Ningxia, and the areas and yields grows fast; the output is 46% of total grain production which is ranking first in the food crops. This paper simulates the impacts of future climate change on maize production in the middle arid region in Ningxia, and explored effective adaptation strategies to mitigate the negative effects of climate change by the crop models.With the meteorological data, soil data, historical production of maize, field observations and experimental data of Ningxia, this paper uses CERES-MAIZE crop model to build the maize growth model in line with the improvement of Ningxia; and assess the impact of future climate simulation on maize growth in the middle arid region in Ningxia with the data of regional climate model A2 and B2 of SRES series of PRECIS system. The main conclusions are as follows:1. Crop model validation:with CERES-Maize model and the data of observations of Yongning, this paper validates the model in time series; and the errors between analog output and growth period and the number of flowering days and the actual data in an acceptable range; the results indicates that this model has a good ability to simulate in time series. This paper validates the model in space with the data of field observation of Zhongwei and the yield data of Tongxin.2. Climate model validation:the paper selects the meteorological data of Tongxin, Yanchi and Haiyuan stations from 1985 to 1990 to validate the applicability of climate models. The results show that the model has a good simulation ablility of temperature especially the low temperature. The model simulates seasonal precipitation well. The model simulates seasonal trends consistent with the actual values of solar radiation, but the analog value is all low and it needs to be amended in the application. The results indicate that the model has a good simulation ability.3. The impact of climate change on maize production in the middle arid region: the maize meteorological yield in the middle arid region is fluctuating flat state from 1988 to 2013; the average temperature during the whole growth increases in volatility by the rate of 0.36℃/10a, and the trend is significant. The precipitation decreases in volatility by the rate of 0.524mm/a; the hours of sunshine decreases in volatility by the rate of 0.965h/a, but the trend is not significant. The maximum temperature during flowered silk-mature period has significant negative impact on maize yield, but the precipitation during this period has significant positive impact on maize yield. When the maximum temperature of flowered silk-mature period increases 1℃, the maize meteorological yield in the middle arid region will decrease 376.935kg/hm2; when the precipitation of this period increases 1mm, the maize meteorological yield will increase 8.310 kg/hm2.4. The impact of future climate change on maize production in the middle arid region:Future climate change will have negative impact on maize growth without considering the CO2 fertilization effect. With climate changing, maize growth and flowing period will be shortened, and yields will be reduced. Because of higher elevations, and lower temperatures, at the beginning of climate change, maize growth period will extend, and yield will increase in southwest; but as temperature continue to rise, the maize yield of entire middle arid region will decrease. In space, the change slow down by the middle to both sides. Since the temperature of B2 is lower than A2 and the precipitation is more than A2, the cut rate of maize of B2 is less than A2. As considering CO2 fertilization effect, the growth period will be almost same as that without considering the CO2 fertilization effect, but the production will be eased. It shows that the increasing of CO2 concentration can compensate for the negative impact of climate change to a certain extent.5. Study of adaptability strategies:Increasing irrigation, improving varieties and advancing sowing can increase the maize yield to a certain extent; among which, improving varieties increase the most yields, in the range of 6.51%～12.80%. The comprehensive measurements can bring better yield effect:increasing irrigation 60mm during seven leaves to teaseling and flowered silk to mature periods,5 days in adventure of sowing and improving varieties.