我国长江中下游农业区冬闲田的遥感监测分析

A Method on Information Extraction of Winter Fallow Fields in Middle and Lower Reaches of Yangtze River by Remote Sensing

近20年以来,随着我国经济结构的调整和农村劳动力的转移,部分地区冬闲田的面积呈明显增长态势。为了科学、合理及高效地利用冬闲田资源,本研究以长江中下游农业区为实验区,利用长时间序列NDVI数据,结合研究区耕地空间分布和农作物在出苗期和成熟期NDVI变化特征,构建了NDVI动态阈值法的冬闲田遥感监测方法,进而对研究区2007至2008年冬闲田的空间分布和闲置时间进行了提取分析。研究发现,2007至2008年,我国长江中下游农业区冬闲田总面积为20.55万km2,占耕地总面积的45.49%。冬闲田集中分布于研究区北部和西北部的江苏、安徽、河南、湖北、湖南和江西的西北部地区,其中,湖北、湖南和江苏是冬闲田分布面积最多的省份,3省冬闲田面积占了研究区冬闲田总面积的53.41%。

In the past 20 years,the area of winter fallow fields showed a steady increase trend because of economic structure adjustment and rural labor transfer in China.In order to make good use of winter fallow fields rationally and efficiently,the dynamic threshold method for winter fallow fields monitoring and relative information extraction was studied based on a long-time series data of the SPOT-VEGETATION NDVI,the spatial distribution of farmland and the characteristics of crop phenology.Then,the spatial and temporal distribution of winter fallow fields in middle and lower reaches of Yangtze River from 2007 to 2008 was extracted as a case study.According to this study,the dynamic threshold method based on NDVI time series data is a good way to extract area information of winter fallow fields.The results indicated that the area of the winter fallow fields in the middle and lower reaches of the Yangtze River was 205.5 million km2,occupying 45.49% of the total cultivated area.The distribution of winter fallow fields was gathered in north and northwest part of the study area including Jiangsu,Anhui,Henan,Hubei,Hunan provinces and northwest regions of Jiangxi Province,in which Hubei,Hunan and Jiangsu provinces have the most largest area of winter fallow fields,which occupied 53.41% of the total winter fallow fields area in the middle and lower reaches of Yangtze River.