Study In The Climate Change And Its Impact On Agricultural Production In Recent 30years In Jiaohe City

Agriculture is the origin of basic livelihood that human society needs to live by,and it directly related to the survival and development of human society. In recent decades, with the common influences of natural condition change and human social activity, global climate is experiencing significant change with the main characteristic of warming. Global warming is bound to cause changes of time and space on the climatic resources that relate with agricultural production and increase the instability of agricultural production. Climatic change has strong impact on China especially.Jiaohe City locates in East Asia monsoon region, which is inevitably influenced by climatic change a lot. Therefore, under the precondition of the bigger climatic variability, evaluation of the influence of climatic change on agricultural production objectively has an important scientific and practical significance in Jiaohe City.With nearly 30 years of meteorological, crop acreage and production data from1981 to 2010, the paper comprehensively analyses the change features and tendency data of principal climatic elements(temperature and precipitation) on time scale of decadal, annual,seasonal, growing season, and monthly with the statistical method of climate tendency rate and linear-regression analysis, and statistically analyses the change rules of evaporation capacity, frost-free season and meteorological disaster(flood, chilling damage, and drought). Finally this paper researches on climatic variation influences in the production of main agricultural crops(corn, rice and soybean) in Jiaohe City. The research result shows that nearly 30 years of average annual temperature of Jiaohe City presents undulating rising trend, annual average rate of calescence is 0.23 ℃/10a; in four seasons of spring, summer, autumn and winter, temperature all present calescence trend, of which, the temperature in summer changes more distinctly, and the calescence rate reaches 0.27 ℃/10 a respectively; The temperature increases significantly in growing season with 0.303 ℃/10 a, which is more than the yearly increasing rate. The yearly maximum temperature increasing rateis 0.23 ℃/10 a, which equals the yearly average increasing rate. The yearly minimum temperature increasing rate is 0.31 ℃/10 a, which is much more than the yearly average increasing rate. In nearly 30 years, the precipitation declines unsteadily in Jiaohe City. The precipitation declines significantly in growing season and most significantly in Summer, with average rate of 53.72 mm/10 a and 31.42mm/10 a.The data of evaporation, frost-free period and meteorological disasters(including flood and water-logging, chilling injury and drought) in Jiaohe City have demonstrated that the yearly evaporation declines much significantly with 95.2 mm/10 a, the frost-free period extends significantly with 1.5 day/10 a. The frequency of rainstorm is almost same in 1980 s, 1990 s and 2000 s, with unforeseeablity, however, the heavy rains occur seldom. The chilling injury tends to weaken or disappear. The frequency of drought increases significantly since the 2000 s.Analyses of the effects of climate change on the yields of main crops show that the rice growing area varies comparably and the growing area of maize and soybean increase unsteadily in Jiaohe City in the nearly 30years; the yearly yields of maize, rice and soybean fluctuate greatly, The maximum yields of maize, rice and soybean are 12598.41 kg/hm2, 11291.50 kg/hm2 and 3989.80kg/hm2 respectively; In nearly 30 years, the meteorological yields of maize vary between 2292.66 and-2047.47 kg/hm2, the meteorological yields of rice vary between3344.85 and-2590.18 kg/hm2, and the meteorological yields of soybean vary between732.54 and-684.63 kg/hm2. The climate has positive effect on the yields of main crops in Jiaohe City.The meteorological yields of maize, rice and soybean vary consistently with the fluctuation of average temperature in growing season, and delay a little bit than the latter; the alteration of main crops is contrary to the change of yield precipitation; the relative meteorological yields of main crops positively correlate with the temperature in growing season, and the degree of correlation is rice >soybean > maize; the relative meteorological yields of main crops negatively correlate with the precipitation in growing season, and the degree of correlation is soybean >maize > rice, of which, only soybean shows a significant correlation. Thus we conclude that the rising temperature and declining precipitation considerably contribute to the increasing yields of main crops. Jiaohe City locates in east mid-levels area where the growth and development of crops benefit from rising temperature due to insufficient heat. The appropriate water requirement for maize,rice, and soybean in growing season is about 400 mm, 590 mm and 490 mm respectively,and the maximum requirement, which occurs in July, is about 130 mm,160mm and 150 mm respectively.There is significant linear correlation among the meteorological yields, the temperature and the precipitation in growing season. The air temperature and precipitation in growing season comprehensively affect the yields of main crops, in descending order of rice, soybean and maize, which is consistent with the order of the effects of temperature on main crops in growing season. These data demonstrate that the first factor affecting the yields of crop is air temperature and the second one is precipitation in Jiaohe City. In nearly 30 years, the meteorological disasters occur more often, which negatively correlate with the yields of crops, and the degree affected is maize > soybean > rice. To summarize, the greastest positive and negative effects of climate are on rice and corn, respectively.