Land Conversion from Marsh Into Cropland in the Sanjiang Plain During the Past 30 Years

To discover the process and rules of regional land conversion from marsh into cropland, based on remote sensing and GIS technology, this paper integrated topographic maps and remotely sensed data, and analyzed the process and driving forces of land conversion from marsh into cropland during 1976-2005. Results showed that, from 1976 to 2005, marsh area decreased by 3/4, from 223.06×10⁴ hm² to 95.87×10⁴ hm². In contrast, cropland increased from 358.67×10⁴ hm² in 1976 to 600.16×10⁴ hm² in 2005. During 1976-2005, the land conversion area from marsh into cropland is 149.39×10⁴ hm², and is 70.13% of marsh area in 1976. The main natural environmental features in relation to land conversion from marsh into cropland are those positions with elevation of 0-100 m, slope gradient of 0-1°, soils of meadow soil, marsh soil and bleaching soil. Statistical cropland areas had good linear relationships with total population and agricultural population.