Tamarix cones play key roles in preventing sand erosion and maintaining regional ecosystem stability. This study aimed to explore the characteristics of soil grain size distribution (GSD) in Tamarix cones across the Taklimakan Desert, verify the relationships between soil grain composition and the fractal dimension, and analyze the relationships between soil GSD and environmental factors. Soils of the Tamarix cones from 0 to 500 cm soil depth were sampled every 20 cm at four sites (Qiemo, Qira, Aral, and Tazhong) along the periphery to the hinterland of the Taklimakan Desert. A total of 300 soil samples were collected to measure soil grain sizes and soil properties. Soil grain size composition was dominated by silt and very fine sand, and the fraction of fine particles decreased and that of the coarse particles increased with soil depth, except for at Tazhong. This suggested that suspension-size particles are the main component of the soil GSD and decrease with the increasing depth in the profiles at the Tamarix cones. The soils were poorly and moderately poorly sorted. Kurtosis generally showed a mesokurtic peak, and the GSD was negatively skewed towards the coarser particles. The fractal dimensions of GSD decreased in the following order Qiemo (2.30) > Qira (2.07) > Aral (1.99) > Tazhong (1.96) because of the increase of coarse particles. The fractal dimension had a strong positive correlation with the clay and silt fractions, and a strong negative correlation with the sand fraction, indicating that the fractal dimension can reflect the characteristics of the soil GSD. The strong relationships between the fractal dimensions and selected soil properties indicate that the fractal dimension can not only quantify changes in soil properties, but also reflect the degree of desertification and degradation in the desert region. Considering the strong wind activities and different deposition sources in the Taklimakan Desert, this study provides a deep insight into the soil formation processes of Tamarix cones within extreme arid desert ecosystems.

Introduction: The precipitation pattern has changed significantly in arid desert areas, yet it is not clear how the water use strategies of Tamarix ramosissima Ledeb. on coppice dunes along a natural precipitation gradient are affected.Methods: In this study, the hydrogen and oxygen isotope compositions of xylem water, soil water, precipitation, and groundwater were measured by stable isotope techniques in Huocheng, Mosuowan, and Tazhong. Additionally, the water use strategies of natural precipitation gradient were investigated in conjunction with the MixSIAR model.Results: The results indicated that the water sources of T. ramosissima exhibited significant variation from semi-arid to hyper-arid areas. In semi-arid areas, T. ramosissima mainly absorbed shallow, shallow-middle, and middle soil water; however, T. ramosissima shifted its primary water sources to middle and deep soil water in arid areas. In hyper-arid areas, it mainly utilized deep soil water and groundwater. In contrast, the water source contribution rate of T. ramosissima exhibited relative uniformity across each layer in an arid area. Notably, in hyper-arid areas, the proportion of groundwater by T. ramosissima was significantly high, reaching 60.2%. This is due to the relatively shallow groundwater supplementing the deep soil water content in the area. In conclusion, the proportion of shallow soil water decreased by 14.7% for T. ramosissima from semi-arid to hyper-arid areas, illustrating the occurrence of a gradual shift in potential water sources utilized by T. ramosissima from shallow to deep soil water and groundwater.Discussion: Therefore, T. ramosissima on coppice dunes shows flexible water use strategies in relation to precipitation and groundwater, reflecting its strong environmental adaptability. The findings hold significant implications for the conservation of water resources and vegetation restoration in arid areas.

Long-term excessive nitrogen application in arid cotton fields increases nitrate leaching risk during fallow and disrupts rhizosphere microecology. To clarify the cross-growth-stage regulatory effects of the biostimulant γ-polyglutamic acid (γ-PGA) combined with chemical fertilizer on rhizosphere microbial communities, we compared chemical fertilizer alone (NK) and γ-PGA plus chemical fertilizer (GT) using rhizosphere soils collected at boll-setting (August) and fallow (October), with physicochemical measurements and metagenomic sequencing technology. At boll-setting, GT lowered pH by 0.74 units compared with NK and increased NH₄⁺-N, NO₃⁻-N, and TN by 339.3%, 491.4%, and 23.0%, respectively. By fallow, GT increased TOC by 70.6% and maintained NH₄⁺-N at 18.38 mg/kg, while NK accumulated 66.85 mg/kg NO₃⁻-N. GT buffered post-harvest fungal community disturbance (Shannon: GT 4.06 vs. NK 2.80) and shifted bacterial communities toward oligotrophic taxa and archaea toward ammonium-preferring taxa. A metagenomic LEfSe analysis showed that GT was enriched in functional genes related to [Q]: Secondary metabolite biosynthesis, transport and catabolism, [T]: Signal transduction mechanisms, and [V]: Defense mechanisms, indicating a shift from resource acquisition to conservative maintenance. Mantel tests revealed that microbial functional profiles showed the strongest association with NH₄⁺-N (r = 0.828 in August, r = 0.883 in October, p < 0.001). Thus, γ-PGA with chemical fertilizer stabilizes fallow rhizosphere microbial communities, reduces nutrient leaching, and promotes carbon–nitrogen co-retention.

Precipitation is a key meteorological factor regulating plant water acquisition and utilization in arid desert environments. However, it remains unclear how the water use strategies of Tamarix ramosissima on coppice dunes at the southwestern edge of the Gurbantunggut Desert respond to precipitation changes, particularly regarding the coordinated relationship between soil water partitioning and leaf water physiological traits. We combined stable isotope analyses (δD, δ¹⁸O and δ¹³C) with key leaf water physiological measurements to examine the water sources and response strategies of T. ramosissima in the different developmental stages of coppice dunes. The results indicate that water use strategies of T. ramosissima are jointly regulated by shifts in water source partitioning and leaf water physiological responses. T. ramosissima in the initial and growth stages of coppice dunes mainly relied on 0–180 cm soil water in spring and autumn but shifted toward 180–500 cm soil water during drought, whereas plants in the stable and declining stages of coppice dunes showed persistent reliance on deep soil water. Notably, T. ramosissima in the declining stage of coppice dunes showed the highest reliance on 180–500 cm soil water under drought conditions (86.5%), accompanied by reduced leaf water status. Following the 7 mm precipitation pulse, T. ramosissima in all coppice dunes increased water uptake from the 0–60 cm soil layer. In particular, T. ramosissima in the growth stage of coppice dunes shifted its water uptake toward the 0–180 cm soil layer. Meanwhile, improved leaf water status enhanced water balance and supported the maintenance of photosynthetic function. By contrast, the 4.2 mm event produced only transient shallow water uptake. The capacity of T. ramosissima to modulate water source partitioning, optimize leaf hydraulic traits, and regulate stomatal conductance forms the basis for its differing water use strategies in all coppice dunes. Such adaptive adjustments allow the species to sustain carbon gain and water balance under variable precipitation regimes, thereby supporting plant growth and ecosystem stability in desert environments. The online version contains supplementary material available at 10.1186/s12870-026-08761-x.