Spatial and temporal changes of multiple cropping index in 1995-2010 in Taihu Lake basin, China

Abstract: The smooth crops growth NDVI curves from 1995-2010 were rebuilt by the HANTS method of Fourier transform techniques, with the combination of 1 km 10 d NOAA-AVHRR time-series NDVI data in 1995 with the resolution of 1 km, 16 d MODIS time-series NDVI data from 2000 to 2010 with the resolution of 250 m, and land use data in 1995, 2000, 2005 and 2010. Spatial and temporal changes of multiple cropping index in 1995-2010 in Taihu Lake basin were extracted by a difference algorithm, and its pattern was analyzed. The results showed that spatial and temporal pattern of multiple cropping index from 1995 to 2010 in Taihu Lake basin was dominated with the double cropping system, while the proportion for the single cropping system was at the increasing trend. Local changes for multiple cropping index with decreasing or increasing trend mainly concentrated in Shanghai Municipality and Zhejiang province. Spatial pattern of multiple cropping index in Taihu Lake basin presented downward trend from north to south, and average multiple cropping index was generally at the obviously decreasing trend, decreasing from 189.4% in 1995 to 167.3% in 2010. The decreasing extent of multiple cropping index from 1995 to 2010 at the county-level for Zhejiang province and Shanghai Municipality was larger than that in Jiangsu province. The combination of the HANTS method and long time-series NDVI remote sensing data to extract multiple cropping index in Taihu Lake basin has high accuracy with 94.6% at the grid scale. Due to the differences in calculation categories and spatial resolution of remote sensing data, the error between the multiple cropping index extracted by the remote sensing method and the statistics at the county-level ranged from 15.8% to 21.6%. The results can provide a scientific basis for policy-making and management of agriculture in Taihu Lake basin.