The lower reaches of the Tarim River in Xinjiang, China are home to desert riparian vegetation dominated by Populus euphratica, which play an important role in windbreak and sand fixation, as well as maintaining the ecological balance of arid regions. Based on dendrochronology, this study analyzed the response of Populus euphratica radial growth to hydrothermal factors in the lower Tarim River region, assessed its resistance and resilience to extreme drought events, developed a multivariate regression model for resilience–hydrothermal factor relationships, and revealed the differential response of its ecological resilience to these factors. The results showed that the maximum, minimum, and mean temperatures and saturated water VPD (vapor pressure deficit) during the spring and growing season were the most significant and positively correlated with Populus euphratica growth. The radial growth of Populus euphratica was negatively correlated with maximum and mean summer temperatures. By region, Yingsu (YS) and Kaerdayi (KE) were more sensitive to seasonal climatic factors. The effect of groundwater on the radial growth of Populus euphratica was the strongest factor, with a highly significant negative correlation (p < 0.01), showing that the radial growth of Populus euphratica slowed with increasing depth of groundwater. The VPD, spring drought severity, and growing season groundwater variability all had a significant effect on Populus euphratica resistance, whereas Populus euphratica resilience was mainly significantly associated with growing season drought severity and summer groundwater variability. Radial growth was positively correlated with spring temperatures and the VPD and negatively correlated with summer temperatures (p < 0.01).

Soil salinization is a major constraint on ecological restoration in arid regions. This study was conducted in the highly saline coal-mining area of Dananhu, Hami, Xinjiang, China. Using a spatial chronosequence approach, we compared soil salt distribution between unplanted bare land and plots planted for 1, 2, and 3 years, as well as ion composition in the roots, stems, and leaves of three halophyte species. The results showed that: (1) Soil salt contents were lower in planted plots than in unplanted bare land. Surface-soil salinity and the sodium adsorption ratio (SAR) differed among plots with different planting durations, with higher values in the 2-year plots than in the 1- and 3-year plots. (2) Na⁺, SO₄²⁻, and Cl⁻ were the dominant soil ions, and their relative proportions differed among plots, particularly in the surface soil. (3) The roots of Tamarix chinensis had a relatively high proportion of SO₄²⁻, whereas the leaves of Nitraria tangutorum had relatively high proportions of Na⁺ and Cl⁻. In contrast, the leaves of Phragmites australis had a relatively low proportion of Na⁺ and relatively high proportions of K⁺ and Ca²⁺. (4) Root Na⁺ contents in T. chinensis and P. australis were significantly positively correlated with SAR in the upper soil layer, whereas stem Na⁺ content in N. tangutorum was significantly negatively correlated with soil Cl⁻, Na⁺, and SAR. These findings highlight differences in soil ionic conditions and plant ion traits among plots with different planting durations.

Understanding the coordination between ecosystem service value (ESV) and landscape ecological risk (ERI) is essential for ecological management in arid inland river basins. However, their spatiotemporal coupling and nonlinear driving mechanisms remain poorly understood. Using the main stem of the Tarim River as a case study, this study integrated multi-source data from 1990 to 2020 with a coupling coordination degree (CCD) model and the XGBoost-SHAP interpretable machine learning framework to investigate the evolution and drivers of ESV–ERI coordination. The results revealed a significant and intensifying spatial clustering of CCD, with Global Moran’s I increasing from 0.741 to 0.793. The basin showed a distinct spatial gradient, with high-value clustering in the upper reaches, transitional differentiation in the middle reaches, and low-value clustering in the lower reaches. Land use intensity (LUI) was identified as the dominant driver, explaining 68.9% of CCD variation. The driving mechanisms varied by river section: the upper reaches were mainly influenced by socioeconomic disturbances, the middle reaches were jointly controlled by LUI and deep soil moisture, and the lower reaches were more sensitive to climate variability and land-use change. Nonlinear analysis further showed an inverted U-shaped relationship between LUI and CCD, with a threshold near 1.53. These findings provide new insights into the spatially heterogeneous and nonlinear mechanisms of ESV–ERI coordination and offer scientific support for ecological risk control and land–water resource management in arid inland river basins.