| Global warming has become an indisputable fact, as one of the most sensitive industry agricultural production which affected by climate change has become a hot issue。 This paper analyzed climate change in the characteristics of wheat in Guanzhong area, which selected the data including temperature, precipitation, sunshine hours day by day, month by month, year by year of the36meteorological stations from1961to2010, using mathematical statistics, mutation analysis, the Arcgis space methods and so on. Then combining yield data about wheat of36counties (districts) of Guanzhong region from1961to2010, it extracted climatic yield of wheat by the methods of benchmark periods. Improving agro-ecological suitability model, and at the same time, building suitability and risk model, the paper analyzed climate suitability, risk and the extreme weather events on wheat production of the9typical counties (districts) under the climate change, which selected specific date about wheat in the9typical counties (districts) from1986to2010in order to provide a reference to cope with global warming, and also to provide theoretical guiding significance for the province’s economic development and to improve crop yields.The main conclusions contain:(1) The climate seasonal charcteristics of Guanzhong area:Summer temperature showed decreasing trend, but the temperature of spring, fall and winter showed the upward trend. The warming trend of winter is the most obvious, and the warming rate was0.40℃/10a. Also spring warming rate increased by0.38℃/10a. The precipitation increased unsignificantly in winter and summer, but it decreased obviously in spring and autumn. And the fall precipitation reduced by the rate of13.25mm/10a, which was faster than the rate of spring precipitation about10.22mm/10a. The sunshine hours of spring showed a weak increasing trend, but the sunshine hours showed downward trend in summer,winter and autumn. The summer sunshine reduced obviously, and the redution rate reached29.7h/10a, which accounted for71%of the whole year. The average temperature of wheat showed significant upward trend at the rate of0.29℃/10a, and also the mean precipatation showed decereasing trend at the rate of17.93mm/10a, at the same time the sunshine hours showed weaking reduction at the rate of3.7h/10a. In all, under the climate change of wheat is consistent with the annual trend of Guanzhong region.(2) The characteristis of climatic suitability and risk in GuanzhongThe climatic suitability increased weakly in Guanzhong area, and it fluctuated between0.5and0.7which appeared three stages, including flutuated, reduced and rising. Also the amount of suitability about temperature, sunshine and climate were more than0.57, however the precipitation suitability were fluctuated between0.25to0.45. The mean suitability of temperature and sunshine increased fast year by year, but the precipitation suitability decreased year by year. The climate risk decreased weakly, and the amount changed in the range of0.15to0.2. The risk to temperature and sunshine showed decreasing trend, which the amount were both below0.15. However the precipation risk increased yeay by year, and the amount varied between0.2to0.25.(3) The influence of extreme weather to wheatThe extreme low temperature below15℃outbroke at the year of1967,1977,1991and2001in the nine typical countries of Guanzhong area, and the frequencies of extreme low temperature reached100%. The extreme low temperature in winter outbroke frequently in the mid of1960s, but into the late1970s, the probability about extreme low temperature increased violently, then by the effects of global warming, the probability occered less. And in the1990s, the occerence of extreme low temperature increased again. In all, the trend fluctuated significantly. The extreme high temperature in maturity of wheat decreased weakly, but the trend remained unchanged, without correlation test. The risk of extreme weather increased, so the yield of wheat decreased. The maximum of the precopitation risk appeared at the year of1986,1995,2001and2008, and the climate risk reached the maximum at the same years. The yield of wheat in the nine typical counties decreased signicifantly in1987,1988,1992,1996,2001and2007, which the annual production was in the lowest level in the same periods of history. |
