Jinnan region is the major producing area for winter wheat in Shanxi province.The area of winter wheat planted in Jinnan region accountes for 96.74 percent of the total area of winter wheat planted in Shanxi province.The changes of distribution of winter wheat in this area are crucial to agricultural decision-making.Remote sensing can obtain different scale ground information,the data update cycle is short,and it is widely used in winter wheat identification.MODIS data has been available for more than 10 years since 2000,and has been widely used in crop planting and long-term monitoring.In this study,based on MODIS data,NDVI (Normalized vegetation index)was used as a band to analyze the spectral characteristics of the main surface features,along with the visible and near-infrared bands.According to the spectral characteristics of the main surface features,the ideal period for extracting the winter wheat information could be determined during wheat period of elongation,and the method of pixel unmixing was optimized.The optimized model of end members was nudation-winter wheat-woodland-water model.The distribution of winter wheat in Jinnan region from 2000 to 2014 was extracted using the optimized method of pixel unmixing.The results were revised by combining the actual statistics,and the percentage of counties with a relative error of less than 15％ was 92.41％ after revising.Then,according to the extracted results,the variation of winter wheat in Jinnan region from 2000 to 2014 was that the area of winter wheat in Jinnan region was overall declining from 2000 to 2014,and largest reduction was in Changzhi.On the other hand,the land use change and the core regions of winter wheat in Jinnan region also could be obtained.However,the change of agricultural land use was influenced by many factors such as crop rotation,price fluctuation,water limitation,and so on.This made it difficult to evaluate the change of winter wheat land use only by comparison of agricultural land use for any two independent years.In this study,the land use of winter wheat and the core regions of winter wheat in Jinnan region were obtained in the base of multi-year cropping probability comparison.The probability was the percentage which the number of actual planting years accounted for the total years in the study period.The larger the percentage was,the higher the probability of planting was,and the higher the probability of the core regions of winter wheat in Jinnan region was.The study period was divided into two periods.One period was from 2000 to 2007,and the other was from 2008 to 2014.By comparing the cultivated probability in this two periods,it was noted that the core regions of cultivated winter wheat in Jinnan region were mainly in Linfen basin and Yuncheng basin,planting probability in Linfen basin changed less,there was a different increase or decrease in planting probability in Yuncheng basin,planting probability decreased more in Jincheng city and drop most in Changzhi basin.
the area of winter wheatMODIS datathe method of pixel unmixingNDVI
NETL
NSTL
万方数据
维普
