关键词: 多项Logistic回归模型, 耕地变化, 生态退耕, 张家口市

Abstract: The Grain for Green Project (GGP) started in Zhangjiakou city, Hebei Province, China in 2000. As an important artificial landscape, cultivated land has functions of ensuring national food security and meeting the needs of urbanization and ecological environment construction land. It is necessary to pay more attention to the differences of cultivated land change and the influencing factors before and after GGP due to the influence of related land policies. By integrating satellite images, geospatial data and socio-economic statistic data, we characterized spatio-temporal dynamics of cultivated land change and micro spatial affecting factors of cultivated land change in Zhangjiakou city before and after GGP (1989-2000 and 2000-2015). This region is located in the farming-pastoral ecotone in North China facing contradictions of developing economy, protecting cultivated land and restoring ecology. The major findings were that cultivated land area continued decreasing from 1 090 031.02 hm² in 1989 to 924 647.32 hm² in 2015, especially after GGP, the rate of cultivated land decreased at annual change rate of -0.84%, totally 132 426.91 hm² cultivated land lost; however, spatial pattern of cultivated land did not change, concentrated in Zhangbei, Kangbao and Guyuan. GGP had accelerated cultivated land conversion speed. Compared with before GGP (1989-2000), conversion area increased 121 695.72 hm² after GGP. Also, the rank of cultivated land conversion type changed remarkably. Cultivated land mainly converted to grassland, construction land, forestland and orchard land before GGP with conversion area of 17 063.59, 9 007.00, 8 932.72 and 5 981.19 hm², respectively, and mainly converted to forestland, orchard land, grassland and construction land after GGP with conversion area of 51 902.41, 40 311.23, 32 292.66 and 23 152.11 hm², respectively. Before GGP, altitude was the leading factor for cultivated land converting to orchard land and forestland, and slope affected most evidently on the conversions from cultivated land to grassland and construction land. After GGP, while altitude remained the dominant factor affecting the conversion from farmland to orchard land, per capita GDP was the most important factor for conversions of cultivated land to forestland and grassland and distance to the nearest road was the significant factor for conversion of cultivated land to construction land. In addition, China’s specific land control policy (prime cropland protection and nature reserves) had an important influence on the conversion of farmland to orchard land, forestland and grassland. In order to protect food and ecology security, the following measures could be taken in Zhangjiakou city: continue to return cultivated land on steep slope and serious desertification regions to forests or grassland moderately, construct ecological farmland which emphasizes farmland system production and ecology safety, establish a differential mechanism for returning farmland to compensation and develop the follow-up industry after GGP. The research results will provide an objective basis for cultivated land protection, ecological protection and socio-economic coordinated development, as well as a scientific reference for similar regions.

Key words: change of cultivated land, Grain for Green Project, multiple Logistic regression model, Zhangjiakou city