Zoning optimization of ecosystem service value and landscape ecological risk in typical karst areas in southwest China

Scientifically evaluating the current ecological environment situation in karst areas and constructing a reasonable ecological zoning system are of great significance for promoting the rational allocation of regional land resources, maintaining ecological security, and driving sustainable development. Based on land use data from 1973 to 2020, the temporal and spatial dynamic evolution of the ecosystem service value (ESV) and landscape ecological risk (LER) were quantitatively analyzed using an ecosystem service model and ecological risk model, and four types of ecological zones were constructed using the Z-score standardization method. The findings indicated that (1) The land use types in Puding County were mainly shrub land (330.61 km²) and dry land (277.34 km²). During the research period, the area of construction land increased most significantly due to the conversion from dry land and paddy fields, with an increased area of 96.55 km². The overall landscape fragmentation and heterogeneity increased, and the landscape diversity remained at a relatively high level. (2) The ecosystem services in Puding County were predominantly regulating services, and the ESV showed a fluctuating trend of decreasing first and then increasing, with a small overall change of 15.11%. The value supplied by shrub land was the highest, accounting for 24.85% of the total value of the study area. The overall ESV showed a spatial allocation pattern of "high in the northeast and low in the southwest". (3) The LER in the study area is mostly low, showing a pattern of being "high in the middle and low around". Accounting for approximately 64% of the total area, the lower and moderate ecological risk zones were the most prevalent. (4) Based on the ESVs and LERs, the research area has been divided into four ecological zones: ecological risk improvement zone, ecological comprehensive restoration zone, ecological function enhancement zone, and ecological conservation and maintenance zone. The different ecological zones had a weak spatial distribution continuity, and the low ESV - low LER zone (III) was the most common. The research results of this study aim to provide an important reference basis for the optimization and scientific management of the ecological environment in karst areas.