Trade-off and synergy evolution of farmland functions and its dynamic mechanism in the process of urbanization

Abstract: Farmland functions have undergone the profound changes in the process of urbanization. It is critical to determine the urbanization driving factors of trade-off and synergy of farmland functions for the better balance between local economic improvements and farmland protection. Taking Huai-Hai Economic Zone as an example, this study aims to establish the assessment system of farmland functions from the dimensions of production, society, and ecology. Spearman Rank Correlation was employed to reveal the spatial and temporal variations of trade-off and synergy of farmland functions from 2000-2018. Subsequently, the moderating effect model was adopted to quantify the driving mechanism of population, land, and economic urbanization, urban-rural income gap, residents' consumption level on trade-off and synergy of farmland functions. The results indicated that: 1) The overall farmland production function was growing continuously, and the growth rate slowed down in the later period. The overall farmland social function dropped continuously, and the decline rate increased in the later period. The overall farmland ecological function declined in 2000-2009 and rebounded in 2009-2018, and it still didn't rise to the initial level. Furthermore, the farmland production functions of all cities were achieved the growth in different cities, where there was the most significant growth of northern Jiangsu. The share of cities with declining farmland social function was 65%, and the growth areas were strip in shape, mainly distributed in the northern Jiangsu and the southern Shandong. Distribution of cities with declining farmland ecological function were the most extensive, accounting for 65%, where the growth areas were mainly distributed in southern Shandong. 2) In the evolution of relationship between farmland functions, the relationship between the farmland production and ecological function was changed from the insignificant trade-off to significant trade-off, and the relationship between the farmland production and social function was changed from the insignificant trade-off to insignificant synergy. Specifically, the trade-off between the farmland production and social function was the most widely distributed, and the trade-off relationship in most cities had been alleviated from 2009 to 2018, the synergy area of which showed the expansion and shifted to the east in the study area. The relationship between the farmland production and ecological function in all cities was trade-off from 2000 to 2009, indicating the synergy in some cities from 2009 to 2018, the synergy area of which was mainly concentrated in the middle south of Shandong and the adjacent northern Jiangsu with the block distribution. 3) The relationship between the farmland production and social function was mainly affected by the urban-rural income gap, population urbanization rate, and residents' consumption level. The synergic development of them was significantly promoted by the residents' consumption level and population urbanization rate, and the growth of urban-rural income gap inhibited the trade-off. The weakening trade-off between the farmland production and ecological function was attributed to the growth of residents' consumption level. Some strategic suggestions were also addressed to promote the synergy of farmland functions in the Huai-Hai Economic Zone.