Human-induced water-environment changes recorded in tree rings in the lower Tarim River

The lower Tarim River is an important ecosystem in the desert of northwest China. However, frequent human activities since the 20th century have caused serious ecological degradation and the desert faces the risk of expansion. Existing studies are limited by the short duration of instrumental data and lack research on the relationship between human activities and ecosystems on a centennial scale. This study used the Populus euphratica ring width chronologies (1816–2020) at two sites in the lower Tarim River combined with hydrological, meteorological, and historical records to evaluate this relationship. The results revealed that the water environment in the lower Tarim River can be divided into five stages according to human activities: a natural runoff period (before 1921), two cutoff periods (1922–1952, 1973–1999) and two recovery periods (1953–1972, 2000–2020). Correlation analysis of chronologies with observational and reconstructed data revealed that before 1940, excessive runoff inhibited tree growth due to high groundwater levels, while after 1940, drought caused by human activity reversed this trend − a dual-stress phenomenon rarely documented in arid ecosystems. Correlation and commonality analyses showed that strong anthropogenic disturbances radically altered the response of tree growth to the environment: after the ecological water conveyance, the impact of environmental factors weakened and was masked by managed water transfer. Our results highlight the dual pressures of excessive and insufficient water on P. euphratica and emphasize the need to optimize groundwater management in restoration efforts, providing insights into balancing water use and ecological restoration in arid regions globally.