Soil Spatial Heterogeneity of the Karkaraly State National Natural Park and Variability of Soil Ecological Properties as a Driver of Biodiversity

The Karkaraly State National Natural Park represents one of the most ecologically significant mountain-steppe ecosystems of Central Kazakhstan, characterized by pronounced landscape heterogeneity and diverse natural conditions. Soil diversity (soil spatial heterogeneity) plays a fundamental role in the formation and maintenance of ecosystem stability, vegetation distribution, and biodiversity conservation within protected natural territories. However, despite the ecological importance of the Karkaraly region, the variability of soil ecological properties and their contribution to biodiversity formation remain insufficiently studied. The present study aimed to assess the soil spatial heterogeneity of the Karkaraly State National Natural Park and evaluate the variability of ecological soil properties as a key factor influencing biodiversity patterns in mountain-steppe ecosystems. Field investigations included 32 soil profiles located along altitudinal and landscape gradients covering forest, meadow, and steppe ecosystems. Soil samples were collected from depths of 0–20 and 20–50 cm and analyzed for pH, humus content, total nitrogen, available phosphorus, exchangeable potassium, soil moisture, carbonate content, salinity, and particle-size distribution. Biodiversity assessment included plant species richness, vegetation cover, Shannon diversity index, and Simpson index. Statistical analyses involved ANOVA, correlation analysis, Principal Component Analysis (PCA), cluster analysis, and GIS-based spatial interpolation. The results revealed substantial spatial heterogeneity of soil ecological properties associated with relief, altitude, parent material, and vegetation patterns. Mountain forest soils demonstrated higher humus and moisture contents, while chestnut and lithogenic soils of steppe areas were characterized by increased carbonate accumulation and lower nutrient availability. Significant positive correlations were identified between humus content, soil moisture, and plant species diversity. The study demonstrates that soil spatial heterogeneity serves as one of the principal drivers of biodiversity and ecological stability in the mountain ecosystems of Central Kazakhstan and provides a scientific basis for biodiversity conservation and sustainable environmental management within protected areas.