Climatic Change Of Dry Farming Area In The Mid-eastern Of Gansu Province And Its Effect On Agricultural Production

Agricultural production is closely related with climate change. Good or bad crop growth and yield level in addition to decided on the biological characteristics of the crops and people's production and business activities, largely dominated by light, heat, water, gas and other climatic factors. Dry farming areas in northwest china rely entirely on natural rainfall, is the sensitive areas of climate change and vulnerable areas of agricultural production. Therefore, grasp the climate change laws of dry farming area in northwest China and fully understand the region's agricultural production which respond to climate change, that has great practical significance to sustainable development of agricultural economy in the region.Based on this, the paper selected Dingxi, Pingliang, Qingyang dry farming areas in the mid-eastern of Gansu province as the research object, using wavelet analysis, kriging interpolation, Mann-Kendall trend analysis and mutation analysis etc., analyzed the agro-climatic resources's (including light, heat, water, wind resources) status, trends, spatial distribution and the coordination degree among climate elements; On this basis, combined with observational data and statistical date of agriculture, analyzed the changes of crop growth, yield and planting structure in study areas and its effect on the response to climate change.The main findings can be summarized as follows: (1) In the recent 48a, heat resources has increased widely in study area, the range of temperature increase: maximum temperature > minimum temperature > average temperature.≥0℃accumulated temperature,≥5℃accumulated temperature and≥10℃accumulated temperature increased significantly, negative accumulated temperature significantly reduced. Steadily pass 0℃, 5℃and 10℃initial day advanced, last days delayed and duration days of study area significantly increased. Heat resources in the study area generally show the cycle of 25a, 11a (12a~14 a), 6a and 2a, and all motated in the 1990s. (2) Average annual precipitition decreased 14.39mm/10a, annual mean evaporation increases 12.43mm/10a, but did not pass the significance test. Annual average precipitation widespread show the cycle of 18a, 4a, 7a, and 2a, and annual mean evaporation show the cycle of 14a (15a), 6a, 11a and 2a. By inspection, there is no obvious motation point of the average precipitation, average evaporation motated in 1993a. (3) Average annual sunshine duriation reduced 9.68h /10a, decreasing trend was not significant; annual average sunshine duriation generally show the cycle of 25a (24a), 11a (12a), 6a (5a) and 2a, but there is no obvious mutation. (4) Annual average wind speed decreased significantly, every 10 years reduced 0.1m/s; Annual average wind speed generally show the cycle of 18a, 24a and 6a; By inspection, the average wind speed motated in 1986a. (5) 2000s compared with the 1980s, the sowing date, seeding stage, stop growth period individual delayed 3~9d, 2~9d and 2~11d in observed areas of winter wheat; After the wintering, other growth stage all advanced, the jointing stage, heading stage, milky stage and mature stage aheaded of 5~11d, 6~14d, 5~15d and 3~14d; Reproductive growth phase of winter wheat advanced, whole growth period shorten 4~23d, the change of the whole growth period days mainly caused by the shorten of overwintering period. (6) 2000s compared with the 1980s, milk stage of spring wheat in the observation area delayed, other growth period all advanced, the sowing date, seedling stage, jointing stage, heading stage and mature stage respectively advanced 1~2d, 2~3d, 2~7d, 2~4d and 6~7d, the whole growth period days of spring wheat reduced 3~12d. (7) In the last 17 years, the actual yield of winter wheat in the observation areas decreased, mainly caused by the drought and high temperature at time of green stage and heading stage; the actual yield of spring wheat also show decreasing trend, yield reduction mainly caused by decreaseing of precipitation in the growing season. (6) Climate warming which makes planting boundary of winter wheat in the study area extended to the northwest. In theory, the entire study area could plant winter wheat, but the northern boundary of winter wheat only represented the average conditions, a region's cropping systems and planting patterns depends not only on climatic conditions, but also according to local conditions make a reasonable judgment.