The spatiotemporal evolution and optimization strategies of ecological security pattern in Panzhihua city over the past 20 years

BackgroundPanzhihua city is an important ecological security barrier in the southwest region. Affected by factors such as long-term high-intensity land development and extensive utilization of mineral resources, the stability of the city's ecosystem has been damaged, facing severe ecological problems including intensified soil erosion, frequent geological disasters, and the risk of land degradation. Constructing its ecological security pattern is of great significance for maintaining the stability of the ecosystem in southwest China and strengthening the ecological barrier in the upper reaches of the Yangtze River.MethodsTaking Panzhihua City as the research object, the ecological source areas were first identified based on the analytical framework of evaluating the importance of ecosystem services - ecological sensitivity evaluation - morphological spatial pattern analysis - landscape connectivity. Then, the basic resistance surface was set in combination with multiple resistance factors. And the ecological elements were identified by using the circuit theory model, thereby constructing the ecological security pattern of this city in the past 20 years (2002-2022). Finally, coordinate the ecological elements of the entire region and propose strategies for ecological restoration and optimization.Results 1) Ecological sources in Panzhihua are relatively concentrated, mainly in Yanbian and Miyi counties in the north. In nearly 20 years, their number has decreased, and area first increased then decreased. 2) The city's overall ecological resistance value has changed little, generally showing a distribution pattern of being higher in the south than in the north and higher in the central part than in the surrounding areas. The low-value areas are mainly concentrated in the northwest, while the high-value areas are clustered in the central part and northeast. 3) Over the past 20 years, the city's ecological corridors have decreased in number, from 38 to 27, and in length, from 216.79 km to 171.10 km. Ecological pinch point areas rose initially then showed an overall increase, from 26.03 km² to 51.08 km². Ecological barrier areas dropped first then presented an overall decrease, from 116.09 km² to 104.66 km². 4) Based on the construction and assessment of the ecological security pattern, the ecological restoration and optimization strategy of "one screen, two belts and four zones" is proposed. Mountain barriers can ensure ecological security within the region. Ecological conservation aim to protect high-integrity landscapes. Ecological restoration area focuses on restoring degraded ecological resources. The ecological control area needs to regulate the intensity of human activities. The ecological improvement area needs to further enhance its ecological functions. Together with the corridor construction - soil pollution prevention and control belt and the water source conservation - soil erosion remediation belt, they constitute the ecological protection network of Panzhihua city.ConclusionsThe research results can effectively optimize the ecological network of Panzhihua city, enhance the ecosystem service functions of the region, and provide certain scientific references for formulating differentiated and targeted protection and restoration strategies to promote the restoration and continuous improvement of the ecosystem.