Pasture use dynamics and resource potential assessment in the Moiynkum Sand Massif: a statistical and spatial approach

Abstract

Pasture degradation in arid regions, driven by climate aridisation and grazing pressure, represents a major challenge for the sustainable management of rangeland resources. This study provides a comprehensive assessment of vegetation dynamics and the factors influencing degradation processes in the Moiynkum Sandy Massif between 2000 and 2024 using remote sensing data, climatic indicators, livestock statistics, and field observations. Vegetation dynamics were analysed using time series of the Normalized Difference Vegetation Index (NDVI) and Fractional Vegetation Cover (FVC). Climatic conditions were characterised by precipitation, diurnal temperature range (DTR), and climatic water deficit (CWD), while wind erosion susceptibility was assessed using the Wind Erosion Potential Index (WEI). Long-term trends were evaluated using the Mann–Kendall test and Sen’s slope estimator, and climate-driven and non-climatic vegetation changes were distinguished using the Time Series Segmentation Residual Trend (TSS-RESTREND) approach. The results showed that areas with moderate (39.62%) and low (24.65%) degradation risk dominated the massif, whereas zones with high and very high degradation risk accounted for 23.91% of the territory. Significant long-term trends included decreasing precipitation, increasing DTR, rising CWD, and enhanced wind erosion potential. Despite the predominance of positive NDVI trends across more than 74% of the study area, TSS-RESTREND analysis indicated that a substantial proportion of vegetation changes could not be explained solely by climatic variability. The coexistence of vegetation greening, increasing climatic stress, and localized degradation hotspots suggests that positive vegetation trends do not necessarily reflect improvements in ecosystem condition. These findings highlight the importance of integrating climatic, ecological, and anthropogenic indicators when assessing land degradation processes in arid rangelands.