Coupling Relationship Between Land Use Transitions and Grain Yield in the Huang-Huai-Hai Plain, China

Land use transition refers to changes in land use morphology, including dominant morphology and recessive morphology, of a particular region over a period of time driven by various factors. Recently, issues related to land use transition in China have attracted interest among a wide variety of researchers as well as government officials. This paper examines the coupling relationship between land use transitions and grain yield in the Huang-Huai-Hai Plain (HHH) during 1990-2010. The HHH includes the areas of five provinces and two municipalities, i.e., the whole of Shandong, most of Beijing, Tianjin, Hebei and Henan, and the northern parts of Anhui and Jiangsu, and covers an area of approximately 400 thousand km(2). The HHH has a population of at least 210 million (2009) and is generally representative of China's plains as a whole. Its land area and population account for 31.7% and 52.6%, respectively, of the total plains area and plains population of China as a whole. The farmland of HHH accounts for about one-sixth of China's total and ranks first in terms of land reclamation rate, with 50 million ha sowing area, 33% of that of the whole country, and producing 35-40% and 60-80% of China's wheat and corn, respectively, which has played an important role in ensuring national food security. The importance of grain production in the HHH is increasing. A series of agriculture and food production support policies began in 2004 that promoted the grain yield in the HHH significantly: the total grain output of approximately 136 million tons in 2008 increased by 27.61% compared to 2000. Land use transition is a mirror of socio-economic development with the changes of both dominant and recessive land use morphologies. Especially, land use intensity is an important attribute of recessive land use morphology, which presents human intervention toward land and regional socio-economic development. Based on the quantitative measure of land use intensity of farmland and rural housing land, this paper describes the changes of recessive land use morphology. Furthermore, the coupling relationship between land use transitions and grain yield (GY) was established. The results show: (1) From 1990 to 2010, the pattern of land use intensity showed prominently difference in HHH, with farmland intensity (LUIF) increased while rural housing land intensity (LUIR) decreased. (2) The spatio-temporal patterns of the coupling types of LUIF, LUIR and GY changed obviously, in which the coupling types of "low-low-low" mainly distributed in the Bohai Bay region, and the coupling types of "high-high-high" concentrated in border area of Hebei, Henan and Shandong provinces; and (3) Land use transitions promote the evolution of grain production with a coupling relationship from antagonism to coordination between two of them. During the process of land use transitions, in conclusion, it is very important for ensuring regional food security by scientific optimizing the coupling relationship between land use transitions and grain yield.