Temporal-spatial transformation characteristics of land use types in composite area of ore-agriculture-urban in Loess Area

Abstract: The transformation of land use type occurs frequently in the composite area of ore-agriculture-urban driven by industrialization, urbanization and urban-rural integration. This transformation is especially affected by the government policy of returning marginal cultivated land to forest and grassland, and reclamation of urban and rural construction occupied land and opencast mining site. This study aimed at revealing the process, characteristics and major causes of land use type transformation in nearly 30 years in the composite area of ore-agriculture-urban in the Loess region. With transformation maps of land use types in the periods of 1986-1996, 1996-2000, 2000-2004, 2004-2009 and 2009-2013, the important values, areas and space distribution of main transformation types were analyzed. The zoning of land use type transformation during 1986-2013 was divided, and the causes of land use type transformation were discussed. The results showed that the differences of transformation types in different periods were obvious and the number of transformation types was increased. There were 17 transformation types in the period of 1986-2013 and the sum of important values of the dominate transformation types was 94.58%, and the other transformation types were 22 and the sum of important values were 5.42%. The sum of important values in different periods presented decreasing trend. The transformation types gradually presented from the state of transformation in farmland to the coexistence of transformation in farmland, transformation between farmland and construction land, transformation between farmland and damage land. The results also showed that all transformation types presented the trends of convergence and diversity in regional distribution. In Xiangyangbao county, Jingping town, Baitang county, transformation from cultivated land into construction land was significant. In the southeast of Jingping town, the northwest of Taocun county, and the middle part of Yuling county, a great amount of cultivated lands became damage lands. Transformation among cultivated land, forestland and grassland was noticeable in the east, the southeast and the north of the studied area. The study area has been divided into regions of farmland transformation to construction land, farmland transformation to damage land, and region of farmland transformation to farmland transformation. Meanwhile, the region of farmland transformation was divided into region of cultivated land transformation to forest land, region of cultivated land transformation to grassland. The areas were nearly balanced on cultivated land transformation to forest land and cultivated land transformation to grassland in the period of 2009-2013. In addition, the results showed farmland decrease was mainly due to the reduction of cultivated land. The cultivated land was the dominant land use type in the transformation by converting into forestland, grassland, rural residential and stripped land, impacted by returning cultivated land to forest land and grassland, occupied construction land and opencast mining damage. The area was 1.01?104 hm2 on cultivated land transformation to forest land and grassland in the period of 1986-2013. The increase of construction land was promoted by urban expansion and land demand for farmers building new houses for improving the living condition and illegal building houses for more land requisition compensation. The area was 0.24?104 hm2 on cultivated land transformation to construction land in the period of 1986-2013. Damage land growth was related to the scale enlargement of coal production. The area was 0.37?104 hm2 on cultivated land transformation to damage land in the period of 1986-2013. The findings can provide references for land sustainable use and protection of ecological environment to the research area.