| At present, climate change has become one of the main problems of the global environment and sustainable development, which has attracted the attention of governments and the public all over the world. The impact of climate change on wetland agricultural crop yield directly, the rice yield decrease; increase the concentration of carbon dioxide is conducive to crop growth, and other factors to inhibit the growth of crops; increasing ultraviolet directly reduced crop production,protein and fat decreased; climate warming will affect China's agricultural climatic conditions and cropping systems, thus affecting the cropping index. But based on the traditional statistical methods to describe an area of multiple cropping index exist timeliness, cost and accuracy of the deficiencies, therefore, extracting multiple cropping index using remote sensing technology has become one of the ideal methods, through the inversion of multiple cropping index of remote sensing data,the analysis of the changing trend, has very important practical significance and application to investigate the value of improving the extraction of multiple cropping index and other aspects of the accuracy.In this paper, on the basis of previous research results, the Ningxia cropping index combined with climatic factors, the effect of climate factors in Ningxia of Ningxia's agriculture, which adapt to climate factors for crops in Ningxia, better conditions, has important significance to reasonable and make full use of land resources and climate resources. The main results and conclusions are as follows:(1) Using the MOD13Q1 data of spatial resolution of 250m to extract the Ningxia multiple cropping index in 2000-2010. The inversion process, the original vegetation index curve is not smooth, the existence of pseudo peak effect caused by low accuracy, based on the SG filtering method of MODIS NDVI/EVI 2000-2010 data were processed, the MODIS NDVI/EVI time series curve correction accords with the actual condition of growth and development of crops in Ningxia, the results of curve correction after the satisfactory.(2) In order to realize the practical application of MODIS NDVI/EVI data products in the extraction of multiple cropping index, the extraction based on EVI data in Ningxia 2009 cropping index as an example, the main process of specific research on the detailed process of extracting multiple cropping index using remote sensing data: the 46 king MODIS EVI time series data, January 1, 2009 -2010 year in December 19th Landsat 5 TM data and statistical data, the key crop phenological information and decision tree classification method based on Extraction of Ningxia 2009 cropping index based on EVI data, analysis of its spatial distribution. The results show that the precision of Ningxia 2009 multi cropping index based on EVI data is as high as 96.4%. The accuracy evaluation results show that the effect is significant.(3) For a more comprehensive analysis of NDVI and EVI two vegetation index extraction differences on Ningxia cropping index, using the 2000-2010 MODIS NDVI, MODIS EVI time series, analyzed two vegetation index extraction differences in key crop phenological value and multiple cropping index, the extraction of NDVI and EVI data of Ningxia in 2001 and in 2009 the cropping index based on the results, show that the high resolution remote sensing image data using time series can be extracted multiple cropping index information accurately, and based on the EVI extracted multiple cropping index higher accuracy than NDVI extraction accuracy based on multiple cropping index. Ningxia in 2009 two crops a year in the area of farmland increased greatly than cultivated area in 2001, the results show that Ningxia is from a year one ripe planting pattern to two crops a year or three years cropping pattern. Climate warming increased the suitable planting area of winter wheat and other crops, and made the maturity of crop varieties in Ningxia region from early maturing to medium late development, multi cropping system northward and multiple cropping index improved.(4) To the climate change trend of Ningxia area, this paper use the 1980-2015,Yinchuan, Taole, Ningxia Huinong defender, Zhongning, Yanchi, Haiyuan,concentric, Xiji, Guyuan and other 10 representative stations in the daily average temperature, precipitation and sunshine hours data, from the overall and partial analysis of two aspects the change trend of three factors in Ningxia in the last 36 years the average temperature, annual precipitation, annual sunshine time. Single factor analysis showed that between the three climatic factors, the maximum correlation with multiple cropping index is the average temperature and the annual precipitation and annual sunshine duration and cropping index is showing low,positive correlation, and multiple regression analysis, multiple cropping index and the climatic factors in the same period from large to small order correlation for annual precipitation, average temperature, annual sunshine hours. The Mann-Kendall non parametric test was used to analyze the abrupt change of climatic factors.(5) After the analysis of the change of the Ningxia climate change and multiple cropping index, found no human factors in case of interference, the change trend of warm drought in Ningxia will lead to increased crop yields in Ningxia, cropping index is also more and more high, but the climate change have different effects on different crops. Therefore, for different crops, different measures should be taken to avoid the disadvantages. The trend of climate change in Ningxia is favorable for agriculture, and the increase of temperature has increased the agricultural heat resources in various regions, and promoted the increase of multiple cropping index and the northward transition of the agricultural climate belt to the north. |
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