Spatio-temporal characteristics of land ecological security and analysis of influencing factors in cities of major grain-producing regions of China

The increasingly critical ecological environment in the major grain-producing regions (MGPRs) of China has attracted widespread attention, but there is limited research at the city level. This study presented a land ecological security (LES) evaluation index system based on the pressure, state, response (PSR) model. It used the panel entropy weight method, kernel density function method, Moran index model, and spatial econometric model to measure LES of 158 cities in MGPRs from 2005 to 2020, and analyzed the spatial and temporal evolutionary trends, spatial divergence characteristics, and influencing factors of LES. The results are as follows. (1) From 2005 to 2020, the overall trend of urban LES level was rising, but it experienced an N-shape fluctuation trajectory of "rise-fall-rise". The state index and response index were on an upward trend, while the pressure index had a certain degree of decline. (2) LES was characterized by the spatial distribution of "high in the north and low in the south" and "high in the east and low in the west", while spatial heterogeneity became increasingly significant, with greater spatial differences within the northern cities and within the central cities. (3) There was a significant spatial spillover effect of LES, but the effect decreased with the expansion of spatial divergence. The spatial association patterns mainly exhibited "high-high" (HH) and "low-low" (LL) agglomerations. (4) The response layer was the main obstacle subsystem, while green space per capita, environmental governance in-vestment, precipitation per capita, arable land per capita, and agricultural development were the main obstacle factors. (5) Economic development, fiscal decentralization, industrial advancement, and innovation input were the positive factors of LES, whereas financial development and industrial development were the negative factors of LES. The findings provide effective policy reference for the sustainable utilization of urban land resources.