中国粮食生产空间关联网络的结构特征及其形成机制

基于1996—2018年中国省际粮食生产面板数据,在修正的引力模型准确测算粮食生产空间关联关系及构建空间关联矩阵的基础上,首先运用社会网络分析方法从整体特征、个体特征及块模型3个方面具体考察了粮食生产空间关联网络的结构特征,进一步采用二次指派程序方法探讨其形成机制。研究发现：① 省际粮食生产空间关联的密切程度在波动中提高,但仍有提升空间,网络结构呈现较好的稳定性和可达性,溢出效应具有多重叠加特性;② 省际粮食生产空间关联网络呈现主产区、主销区、平衡区“核心—边缘”分布格局,粮食主产区在网络中处于核心地位,粮食主销区和平衡区则处于边缘地位;③ 粮食生产空间关联网络可划分为净溢出、主受益、经纪人和双向溢出4个板块,板块间的溢出效应具有明显的梯度传递特征;④ 自然禀赋条件与社会经济因素的共同作用推动了粮食生产空间关联网络的形成,地理空间邻近性、经济发展水平与农村劳动力规模、机械服务规模、耕地资源的差异、降水量和日照时数的相近性对粮食生产空间关联网络的形成具有显著影响。

Structural characteristics and formation mechanism of spatial correlation network of grain production in China

Based on the panel data of China's inter-provincial grain production from 1996 to 2018, the modified gravity model was used to accurately calculate the spatial correlation of grain production and build a spatial correlation matrix. Firstly, the structural characteristics of grain production spatial correlation network were investigated from three aspects: overall characteristics, individual characteristics and block model through the social network analysis method (SNA) and then, the quadratic assignment procedure (QAP) method was used to explore its formation mechanism. The study found that: (1) The level of inter-provincial spatial correlation of grain production increases in fluctuation, but there is still room for improvement. The network structure shows better stability and accessibility, and the spillover effect has multiple superposition. (2) The inter-provincial spatial correlation network of grain production presents a significant core-edge distribution pattern of major grain-producing areas, main-sales areas and grain balance areas, and the major grain-producing areas are at the core position in the network, and the grain main-sales areas and the balance areas are at the edge. (3) The spatial correlation network of grain production can be divided into four functional blocks, namely, net spillover block, main beneficial block, broker block and bidirectional spillover block, and the spillover effect between blocks are featured by obvious gradient transmission. (4) The combined effect of natural endowment conditions and socio-economic factors promote the formation of spatial correlation network of grain production. The geographical proximity, differences in economic development, rural labor scale, mechanical service scale and cultivated land resources, and the similarity of precipitation and sunshine hours have significant impacts on the formation of spatial correlation network of grain production. The conclusions are of great significance for us to grasp the spatial transmission mechanism, realize the cross-regional coordination and formulate differentiated grain policies in China.