Analysis of influencing factors of cultivated land change in Chinese urban agglomerations considering spatially inter-city interactions

As the basic means of agricultural production, cultivated land plays an irreplaceable role in ensuring food security and promoting social and economic development. With the enhancement of urban interactions in space, the land use conflicts between urban development and agricultural protection have been intensified due to the diversified land demands caused by population agglomeration, industrial restructuring and infrastructure construction. Exploring the impacts of urbanization on cultivated land change has become a hot issue in China at present. Most of current studies have paid increasing attentions to the relationship between the growth of individual cities and cultivated land occupation, and few of them attempted to reveal the driving factors of cultivated land change from the perspective of spatial interaction of cities. Urban agglomeration is the main form of new urbanization in China. It is crucial to identify the distribution of cultivated land change and its driving factors from the perspective of urban agglomeration. In this paper, we measured the spatial connection of urban agglomerations based on the gravity equation and the urban flow intensity model, and then explored influencing factors of cultivated land conversion at the scales of individual cities and urban agglomerations during the period of 2005-2015 using a multilevel linear regression model. The research results show that the area of cultivated land in the major urban agglomerations has dropped sharply by 17 572.8 square kilometers in the decade from 2005 to 2015. The situation of cultivated land protection is grim. Then it shows significant scale effects and regional heterogeneity of cultivated land change in urban agglomerations. At the urban scale, the change of cultivated land is positively correlated with agricultural population, industrial economy and agricultural science & technology development, whereas negatively correlated with the growth of foreign investment and the expansion of construction land. At the scale of urban agglomeration, both indicators of spatial connection have a negative correlation with cultivated land change. Moreover, remarkable regional differences of influencing factors of cultivated land change exist between coastal and inland China. Comparing the regional differentiation of the degree of influence of outward functional forces, it can be found that the spatial interaction of coastal urban agglomerations has a more positive effect on the protection of cultivated land than the inland urban agglomerations with relatively backward development, and the negative impact is also smaller than that of inland urban agglomerations. The comparison with other models verified the effectiveness of the multilevel linear regression approach to reveal the influencing mechanism of cultivated land change on different scales. And the result of null model has proved the necessity and rationality in the research perspective of spatial interactions between cities. As a word, the strengthening of spatial interaction in urban agglomerations under rough development will obstruct the protection of cultivated land. In this case, controlling industrialization and urbanization reasonably, concerning the scale effects and regional heterogeneity, improving laws and regulations, correcting the rough development path, and improving land use efficiency might be the critical roads to relieve conflicts between development of urban agglomerations and protection of cultivated land.