Desert grasslands are critical carbon sinks in arid regions, where herbaceous species selection plays a vital role in ecosystem restoration. While plant life cycle (annual vs. perennial) is known to affect soil organic carbon (SOC) stocks, its influence on SOC molecular composition remains poorly understood. This study examined the accumulation and environmental drivers of plant- and microbial-derived carbon biomarkers (lignin phenols and amino sugars) across the 0-40 cm soil profile under four desert herbaceous species: perennial Karelinia caspica (Pall.) Less. and Glycyrrhiza inflata Batalin., annual Chenopodium glaucum L. and Salsola lanata (Pall.) Botsch. Plant-derived C contributed more to SOC (9-15%) than microbial-derived C (3-8%), with contributions differing significantly between plant life cycles. These differences were shaped primarily by edaphic factors: plant-derived C accumulation was mainly regulated by pH, whereas microbial-derived C was affected by labile organic carbon (LOC), elemental stoichiometry (C/N, C/P), electrical conductivity, and pH. Our results indicate that herbaceous species influence SOC sequestration through divergent plant and microbial pathways. Perennial species, especially K. caspica and G. inflata, enhance SOC storage more effectively and should be prioritised in desert grassland restoration.

Dryland vegetation may shift abruptly when growing-season precipitation falls below critical levels, yet whether threshold crossing reorganizes vegetation controls remains unclear. We developed a PCA-based similarity-window drought-threshold framework to detect vegetation drought thresholds in Northwest China using 2001–2024 NDVI and growing-season precipitation records. Interpretable XGBoost-SHAP models compared driver importance before and after threshold crossing, and the CMIP6 model INM-CM5-0 estimated late-century changes in threshold-crossing risk under SSP1-2.6, SSP2-4.5, and SSP5-8.5. Significant thresholds occurred in 32.36% of valid vegetated pixels, with a median precipitation threshold of 285.15 mm; 42.59% occurred below the local 20th percentile, indicating that a substantial fraction of responses emerged only under severe drying. Temperature importance increased by 51.9% after threshold crossing. Future risk changes were spatially heterogeneous and stronger under SSP5-8.5, with risk-increase hotspots in eastern Qinghai and southern Gansu. The framework supports ecological drought monitoring.

In arid regulated rivers worldwide, ecological water transfer (EWT) is increasingly used to restore degraded river corridors, yet its effectiveness is commonly evaluated using water-delivery volume, downstream channel reconnection, groundwater recovery, or average vegetation improvement. Whether these indicators adequately represent the spatial extent of vegetation recovery remains insufficiently quantified, particularly at the individual-tree scale. This study aimed to quantify the effective restoration footprint of long-term EWT in the lower Tarim River and to determine whether groundwater recovery alone adequately represents ecological restoration success. We combined field survey data for more than 5000 Populus euphratica trees, very high-resolution satellite imagery from 2005 to 2022, and groundwater records from six monitoring wells located approximately 50-1050 m from the river channel. Vegetation change was quantified as ΔNDVI at mapped tree locations and analyzed using generalized additive models and distance-class summaries, while groundwater trends and lagged associations with annual EWT volumes were assessed using the Mann-Kendall test, Sen's slope estimator, and Spearman's rank correlation. Groundwater depth decreased significantly at all six wells during 2001-2022 (Sen's slopes: -0.127 to -0.230 m yr-1; p ≤ 0.002), indicating a coherent rise in the groundwater table across the riparian corridor. The zone-level association between NDVI and groundwater depth weakened markedly between 2005 and 2022. However, vegetation recovery was spatially bounded: mean ΔNDVI was high within 0-300 m of the channel (0.170-0.196), declined sharply in the 300-500 m transition band (0.051), and approached near-zero values beyond 500 m (0.013-0.038). Moreover, the zone-level NDVI-groundwater association weakened from strong and significant in 2005 (Spearman's ρ = -0.94, p = 0.005) to weak and non-significant in 2022 (ρ = -0.20, p = 0.704). These findings highlight the joint importance of water-table recovery and the spatial accessibility of EWT in shaping riparian greening. Incorporating the effective restoration footprint into EWT assessment may improve the spatial efficiency of water allocation and support more targeted riparian forest restoration in arid regulated rivers.

Free-range cattle farming has resulted in considerable challenges to the ecology and environment in pastoral areas, particularly in relation to local water quality in pastoral lakes. This study investigated the impact of cattle manure (CM) on pasture water quality evolution in a typical pasture in arid regions, especially the pollution contribution of nitrogen (N) and phosphorus (P). Fresh cattle manure (FCM) and dry cattle manure (DCM) were analyzed in a traditional pasture. The results indicated that FCM contained higher N and total organic carbon than DCM. Leaching experiments revealed that FCM released more N and P into pastoral water than DCM. However, soil adsorption and desorption experiments demonstrated that soil in pastoral areas reserve N and P from CM, reducing N and P water pollution contribution. Furthermore, the predominant organisms in FCM, such as Proteobacteria and Bacteroidota, inhibited the release of N and P from CM. The quantified pollution load from CM to water quality deterioration revealed that the contribution of N and P inputs was below 1 %, indicating that CM is not a major driving factor for water quality decline. Therefore, although CM contributes to pollution load, its impact on water quality evolution is limited compared to that of other anthropogenic factors (local industry and agriculture). This study provides new insights into integrated management strategies for protecting the ecological health in pasture.

Groundwater storage anomalies (GWSA) are important indicators for groundwater security and sustainable water governance in arid inland river systems. This study investigates long-term GWSA trends along the Tarim River mainstream during 1990–2020 using a 1-km downscaled GWSA dataset and crop-specific land-use analysis. Results show a persistent decline in GWSA at a rate of −0.451 cm/year, with greater losses in the upper and middle reaches. Spatial variation is primarily associated with cropland expansion, impervious surface growth, and regional hydroclimatic variability. Land-use change dominates the long-term pattern of groundwater depletion, whereas climate variability remains an important co-driver of seasonal and interannual groundwater fluctuations. Additional analysis based on crop-area statistics from the main administrative regions along the Tarim mainstream indicates that the expansion of high-water-demand crops, particularly cotton, grapes, and red dates, is associated with lower groundwater storage conditions. By quantifying the relative roles of climate variability and land-use change across subregions, this study provides evidence for spatially targeted and crop-sensitive groundwater governance and sustainable irrigation management in arid inland river systems.

Branch architecture is the spatial structure formed by branching within the canopy, which directly affects tree growth, function, and ecological adaptation. To reveal the morphological adaptation mechanisms of Populus euphratica to extremely arid environments, we used terrestrial laser scanning to scan 51 individual P. euphratica trees in the lower reaches of the Tarim River. We reconstructed the branch structure using the quantitative structural model TreeQSM, extracted the geometric parameters of first- to third-order branches, and analyzed the allometric relationships among different branch orders, vertical distribution patterns of branches, as well as the correlations between architectural parameters (number of branche, length, and angle), and tree structural parameters (tree height, diameter at breast height, crown base height, crown diameter, crown area, crown volume, and crown height ratio). The results showed that the mean numbers of first-, second-, and third-order branches of individual trees were 9.2, 68.1, and 567.1, respectively; the corresponding mean branch lengths were 2.70, 1.18, and 0.30 m; and the mean branch angles were 53.30°, 61.33°, and 62.61°, respectively. With increasing branch order, branch number increased, branch length decreased, and branch angle increased slightly. The ratios of branch number of first- to second-order branches and second- to third-order branches were 1:8 and 1:9, respectively, while the corresponding length ratios were 2.15:1 and 4:1. Branches were mainly distributed within the 3-5 m canopy height range. The lengths of first- and third-order branches decreased with increasing canopy height, whereas second-order branch lengths varied only slightly with canopy height. Among the first- to third-order branches, all architectural parameters except the number of first-order branches increased with increasing diameter at breast height (DBH). The numbers and lengths of first- to third-order branches in P. euphratica exhibited clear allometric growth patterns and vertical distribution characteristics, and DBH was an important structural parameter for characterizing branch architecture. These results would provide support for fine-scale structural inversion and quantitative functional studies of P. euphratica branches.

The positive impact of urban green space on residents’ health has been exten-sively explored. However, previous studies have focused on exploring the impact of park physical characteristics on park use in developed countries, little attention to the compre-hensive effect of physical and psychological factors on usage patterns and perceived bene-fits. In fact, both push and pull forces jointly influence the usage patterns and perceived benefits. we conducted a face-to-face survey of 295 respond-ents in 6 parks and used mediation model to reveal the impacts push-pull motivations on park satisfaction, usage patterns and per-ceived benefits. The results showed that aesthetic and natural qualities and safe are the main pull factors. Landscape service motivation has the highest score in push factors, fol-lowed by sports, restorative and interpersonal motivation. Pull factors such as accessibil-ity, safety, infrastructure and landscape patterns are not the only factors positively related to park use and self-perceived benefits; recreation and interpersonal motivation also affect usage patterns and perceived benefits. The introduction of push factors increases the ex-planatory power of regression model, but also weakens the contribution of pull factors. The mediation model results reveal that push-pull factors are indirectly affected by the potential mediation adjustment of satisfaction on usage patterns and perceived benefits. The results suggest that paying attention to respondents’ motivation to improve park characteristics can effectively improve park satisfaction and indirectly improve park use and perceived benefits, which can serve as a reference for urban park management.

The integrity of habitat quality is a pivotal cornerstone for the sustainable advancement of local ecological systems. Rapid urbanization has led to habitat degradation and loss of biodiversity, posing severe threats to regional sustainability, particularly in extremely vulnerable arid zones. However, systematic research on the assessment indicators, limiting factors, and driving mechanisms of habitat quality in arid regions is notably lacking. This study takes Urumqi, an oasis city in China’s arid region, as a case study and employs the InVEST and PLUS models to conduct a dynamic evaluation of habitat quality in Urumqi from 2000 to 2022 against the backdrop of land use changes. It also simulates habitat quality under different scenarios for the year 2035, exploring the temporal and spatial dynamics of habitat quality and its driving mechanisms. The results indicate a decline in habitat quality. The habitat quality in the southern mountainous areas is significantly superior to that surrounding the northern Gurbantunggut Desert, and it exhibits greater stability. The simulation and prediction results suggest that from 2020 to 2035, habitat degradation will be mitigated under Ecological Protection scenarios, while the decline in habitat quality will be most pronounced under Business-As-Usual scenarios. The spatial distribution of habitat quality changes in Urumqi exhibits significant autocorrelation and clustering, with these patterns intensifying over time. The observed decline in habitat quality in Urumqi is primarily driven by anthropogenic activities, urban expansion, and climate change. These factors have collectively contributed to significant alterations in the landscape, leading to the degradation of ecological conditions. To mitigate further habitat quality loss and support sustainable development, it is essential to implement rigorous ecological protection policies, adopt effective ecological risk management strategies, and promote the expansion of ecological land use. These actions are crucial for stabilizing and improving regional habitat quality in the long term.

Populus euphratica (P. euphratica) is a key desert riparian plant species in central Asia. This species has adapted to harsh habitat conditions by excreting salts in the form of P. euphratica secretion (PES). PES is known to have therapeutic benefits for ailments such as sore throats, gastrointestinal disorders, and neurasthenia. Meanwhile, local inhabitants harvest PES for the preparation of an alkaline paste, a digestive beverage for their diet and flour leavening agent. Despite its various uses, the chemical composition of PES remains to be elucidated. In this study, the elemental and ionic composition of PES was quantitatively analyzed using elemental analysis, ICP-OES, ion chromatography, and potentiometric titration. The main inorganic compounds were determined by X-ray diffraction. Na, K, Ca, Mg, Cl-, HCO3- and SO42- were identified in PES. Na2CO3·NaHCO3·2H2O (Trona) and KCl, the two main components, were found and quantified in PES for the first time. Additionally, NaHCO3, NaCl and SiO2 were also detected in PES. This work thoroughly characterized PES, a highly nutritious and culturally valued food material, through qualitative and quantitative analyses, fully elucidating its inorganic chemical composition. These findings address several gaps in the fundamental composition data of PES and support its physiological functions in plants and potential health benefits in traditional applications.

Understanding gap patterns and their dynamics in response to climate change is essential to reveal the regeneration-survival trade-offs in dryland forests. However, few studies have quantitatively assessed forest gap characteristics in regions undergoing significant environmental stress beyond hydrological and temporal influences. This study investigates temporal gap dynamics in Tugai forests along the Tarim River corridor using field survey datasets collected at 1-year intervals. A total of 60 forest gaps were monitored over an extended period in northwestern China. We analyzed the distribution characteristics of gap sizes, gap makers, gap border trees, and gap regenerations, and examined how climate change influenced gap size and tree mortality using correlation analysis. Our findings show that small- to medium-sized gaps (> 200 m(2)) were prevalent, and young tree mortality (basal diameter < 20 cm) occurred frequently. Most dead trees were either broken or uprooted (77.23%). Increasing temperatures and increased drought severity had a more substantial effect on gap dynamics compared with that of precipitation and evaporation. The gap size and mortality rates substantially increased under rising temperatures and drought severity during the summer (May-September). In contrast, the diameter at breast height of tree mortality decreased. Long-term climatic stress since the 1970s has heightened the sensitivity of dryland Tugai forests to temperature and water availability. Our research emphasized that Tugai forest dynamics will be significantly degenerated by climate change in the future under increasing water scarcity. This study enhances our understanding of the impact of meteorological drivers on degraded ecosystems and proposes management strategies for conservation projects in desertification areas that are confronted with climate change.

Litterfall load is crucial in maintaining ecosystem health, controlling wildfires, and estimating carbon stock in arid regions. However, there is a lack of spatiotemporal analysis of litterfall in arid riparian forests. This study aims to estimate Litterfall load using a BP neural network based on vegetation indices from Landsat 5 and 8 satellite images, litterfall inventory data, slope, and distance to major river tributaries. It also aims to analyze the spatiotemporal distribution pattern of litter in the research area by estimating and analyzing the spatiotemporal pattern of litterfall along the desert riparian forests of the lower Qarqan and Tarim Rivers from 2001 to 2021. The results show that the initiation of the ecological water transfer project has facilitated the decomposition of litterfall, leading to an initial decline. Subsequently, the vegetation gradually recovered, leading to an increase in leaf litter input. Since 2001, litterfall initially decreased until reaching its lowest value of 4.39 × 109 kg in 2005, followed by a subsequent increase, reaching its highest value of 12.5 × 109 kg in 2021. The study concludes that ecological water conveyance promotes both the decomposition and increase of litterfall. Initially, it accelerates litterfall decomposition, while later stages foster an increase in Litterfall load. Meanwhile, due to the ecological water transfer project and the higher vegetation cover along the Tarim River compared to the Qarqan River, the Tarim River basin experiences higher average Litterfall load and variation.

Individual tree segmentation (ITS) is essential for forest inventory, health assessment, carbon accounting, and evaluating restoration efforts. Populus euphratica, a widely distributed desert riparian tree species found along the inland rivers of Central Asia, presents challenges for accurately identifying individual trees and conducting forest inventories due to its complex stand structure and overlapping crowns. To determine the most effective ITS approach for P. euphratica, we benchmarked six commonly used tree segmentation approaches for terrestrial laser scanning (TLS) data: canopy height model segmentation (CHMS), point cloud segmentation (PCS), comparative shortest-path algorithm (CSP), stem location seed point segmentation (SPS), deep-learning trunk-based segmentation (TBS), and leaf–wood separation-based segmentation (LWS). All methods followed a unified preprocessing and tuning protocol. We evaluated these methods based on tree-count accuracy, crown delineation, and structural attributes such as tree height (H), diameter at breast height (DBH), and crown diameter (CD). The results indicated that the TBS and LWS methods performed the best, achieving a mean tree-count accuracy of 98%, while the CHMS method averaged only 46%. These two methods provide the basic branch structure within the tree crown, reducing the likelihood of incorrect segmentation. Validation against field-measured values for H, DBH, and CD showed that both the TBS and LWS methods achieved accuracies exceeding 80% (RMSE = 0.8 m), 86% (RMSE = 0.02 m), and 73% (RMSE = 0.7 m), respectively. For TLS data in P. euphratica desert riparian forests, these two methods provide the most reliable results, facilitating rapid plot-scale inventory and monitoring. These findings establish a practical basis for conducting high-accuracy inventories of Euphrates poplar desert riparian forests.

Populus euphratica is a drought-tolerant species unique to desert region that plays a crucial role in carbon sequestration in desert oases. However, how plant-and microbial-derived C contribute to soil organic carbon (SOC) changes during stand development and the influence of soil environmental factors on these changes remains unclear. Here, biomarkers (amino sugars and lignin phenols) were used to track contributions of plant-and microbial-derived C to SOC at two soil depths (0-20 and 20-40 cm) in P. euphratica desert forests of four stand ages (5, 15, 30 and 105 years). The contribution of microbial-and plant-derived C to SOC increased with stand age in 0-20 cm soil layer. Among these, plant-derived C made a higher contribution to SOC compared to microbial-derived C (2.2-17.8 % and 1.1-13.1 %, respectively), and the contribution of bacterial-derived C to SOC was lower than that of fungal-derived C. Gradual increases in total nitrogen (TN), total phosphorus (TP), and the silt-clay mixture content were observed in the 0-20 cm soil layer with stand age. Stand development enhanced phenol oxidase activity in both two depths. Additionally, the accumulation of plant-derived C was strongly correlated with plant above-ground biomass and soil nutrients (TN and TP), and shifts in microbial-derived C accumulation were induced by the increase in soil silt-clay mixture content during stand development. Our study offers novel insights into SOC accumulation in P. euphratica forests of extreme arid areas, and helps elucidate the distinct mechanisms of plant-and microbial-derived C accumulation in desert soils during forests development.

Since its implementation in 2000, the ecological water diversion project (EWDP) has played a pivotal role in rehabilitating degraded desert riparian woodlands in the Tarim River Basin. While an extensive body of peerreviewed research has objectively quantified the EWDP impacts on Populus euphratica forest regeneration, the predominant reliance on limited tree architectural variables employed in previous studies has constrained deeper understanding of riparian forest-EWDP interactions. This study synthesizes 635 observational datasets extracted from 21 rigorously screened publications searched in Web of Science Core Collection and China Knowledge Network Literature Database (CNKI) through a meta-analytical framework to systematically evaluate EWDPecological responses of P. euphratica under varying water management regimes. Our results demonstrate that EWDP significantly enhanced degraded forest recovery metrics, with mean increases of 60.28 % (crown diameter), 6.73 % (radial growth), 8.1 % (branch growth), and 12.81 % (growth ring index), respectively. Multivariate analysis identified dual-channel water diversion as the optimal delivery method, with peak efficacy achieved at annual water allocations of 3 x 108 to 6 x 108 m3 during the P. euphratica growing season (minimum 120 days duration). Notably, a 1-2-year lag effect was observed between water delivery initiation and measurable recovery responses. These findings establish an operational threshold for ecological flow releases and highlight the critical need for phenology-driven water scheduling aligned with P. euphratica species' hydraulic requirements. The proposed adaptive water management framework provides critical insights for optimizing water allocation strategies and ecological rehabilitation in arid regions under increasing hydrological uncertainty.

The green landscapes of oasis cities play an important role in maintaining ecological security. However, these ecosystems face increasing threats from desertification and fragmentation, driven by intensifying climate change and rapid urbanization. Understanding the characteristics and driving mechanisms behind changes in green landscape patterns is crucial for advancing sustainable urban green space management. This study explores the spatio-temporal changes in the green landscape pattern in Urumqi during 1990–2020 using a random forest classifier. This study also applies geographical detectors and geographically weighted regression to comprehensively determine the driving mechanism and spatio-temporal nonstationarity. The results are as follows: (1) The landscape types are primarily dominated by unused land, urban green spaces, and construction land, accounting for more than 80%. The areas of urban green spaces, water bodies, cropland, and unused land decreased by 0.38%, 37.41%, 0.57%, and 4.58%, respectively, from 1990 to 2020. With rapid urbanization, construction land exhibited a significant expansion trend, and the degree of fragmentation of urban green spaces increased spatially over these 30 years. (2) From 1990 to 2020, each landscape index exhibited fluctuating characteristics. Overall, the Shannon’s diversity and evenness indices of the urban green landscapes exhibited an increasing trend. The contagion and connectivity indices exhibited a decreasing trend, decreasing from 50.894 and 99.311 in 1990 to 46.584 and 99.048 in 2020, respectively. (3) During these 30 years, the dynamics of urban greenery were affected by a combination of natural and social factors, with elevation determining the overall urban green distribution pattern. Precipitation and temperature dominate the urban green space changes in the north and south of Urumqi. Socioeconomic factors such as GDP, population, river distance, and town distance regulate the urban green space changes in the central built-up area.

Land use and landscape changes undermine the balance between humans and the environment, threatening sustainable regional development, yet their driving mechanisms and future trends remain insufficiently understood, particularly in arid areas. This study establishes a long-term analytical framework for the temporal evolution and driving mechanisms of land use and landscape patterns in arid areas, based on Landsat remote sensing imagery and socio-economic data. We investigate spatiotemporal evolution trends, driving mechanisms, and spatial non-stationarity of regional landscapes, and apply the Patch-generating Land Use Simulation (PLUS) model to predict future landscape changes under business-as-usual (BAU), economic development (ED), and ecological protection (EP) scenarios. The results show that: (1) Grassland and unused land together account for over 80% of the total area. From 1990 to 2020, built-up land expanded by 1471.58 km2, an increase of 190.09%. The comprehensive land use dynamic degree in the Urumqi–Changji–Shihezi (UCS) region was 0.22%, with the highest value observed between 2000 and 2010. (2) At the class level, spatial heterogeneity and fragmentation of different landscape types increased, enhancing regional landscape diversity. (3) Spatiotemporal changes in land use and landscape patterns were driven by the combined effects of natural factors, socio-economic conditions, and policy influences. (4) By 2030, under all three scenarios, unused land is expected to decrease, with the most significant reduction under the EP scenario. Grassland will increase most notably under the EP scenario, built-up land will expand, especially under the ED scenario, and cropland will also grow, mainly under the EP scenario. Forest and water areas will show slight decreases with minimal fluctuations. Overall, the proposed framework effectively captures the spatiotemporal dynamics and driving forces of land use and landscape changes, providing support for the formulation of long-term sustainable development policies.

The Populus euphratica desert riparian forest, predominantly distributed along the Tarim River in northwestern China, has experienced significant degradation due to climate change and anthropogenic activities. Despite its ecological importance, systematic assessments of P. euphratica stand structure across the entire Tarim River remain scarce. This study employed terrestrial laser scanning (TLS) to capture high-resolution 3D structural data from 2741 individual trees across 30 plots within six transects, covering the 1300 km mainstream of the Tarim River. ANOVA, PCA, and RDA were applied to examine tree structure variation and environmental influences. Results revealed a progressive decline in key structural parameters from the upper to lower reaches of the river, with the lower reaches showing pronounced degradation. Stand density decreased from 440 to 257 trees per hectare, mean stand height declined from 9.3 m to 5.6 m, mean crown diameter reduced from 4.1 m to 3.8 m, canopy cover dropped from 62% to 42%, and the leaf area index fell from 0.51 to 0.29. Age class distributions varied along the river, highlighting population structures indicative of growth in the upper reaches, stability in the middle reaches, and decline in the lower reaches. Abiotic factors, including groundwater depth, soil salinity, soil moisture, and precipitation, exhibited strong correlations with stand structural parameters (p < 0.05, R2 ≥ 0.69). The findings highlight significant spatial variations in tree structure, with healthier growth in the upper reaches and degradation in the lower reaches, enhance our understanding of forest development processes, and emphasize the urgent need for targeted conservation strategies. This comprehensive quantification of P. euphratica stand structure and its environmental drivers offer valuable insights into the dynamics of desert riparian forest ecosystems. The findings contribute to understanding forest development processes and provide a scientific basis for formulating effective conservation strategies to sustain these vital desert ecosystems, as well as for the monitoring of regional environmental changes.

Variation in physical and chemical properties of Populus euphratica Oliv. heartwood and sapwood under different groundwater depths reflect species-specific water and nutrient requirements. This study examines natural P. euphratica forest in the Arghan section of the lower Tarim River, analyzing groundwater depth-dependent changes in heartwood and sapwood characteristics and their interrelationships. Results demonstrate that heartwood rate exhibited the highest coefficient of variation (78.41 %), while heartwood density showed the lowest (7.57 %). With the increase of groundwater depth, both heartwood radius (HR) and sapwood width (SW) initially increased and then decreased. Heartwood area (HA) remained consistently larger than sapwood area (SA), and both showed significant differences under different groundwater depths (p < 0.05). HR, HA, and SW exhibited significant positive correlations with groundwater depth (p < 0.05). Chemically, maximum heartwood cellulose content occurred at 8.2 m groundwater depth, while sapwood cellulose peaked at 4.8 m. Heartwood consistently displayed higher cellulose content than sapwood at equivalent groundwater depths. Both heartwood and sapwood lignin contents reached maxima at 4.3 m groundwater depth. Random forest analysis identified heartwood cellulose, lignin content, and heartwood density as the most responsive parameters to groundwater depth variations. These findings suggest P. euphratica adapts to arid environments through optimized water utilization and physiological trait adjustments under water stress conditions.

Selecting the appropriate roofing material is crucial for addressing the urban heat island effects. However, uncertainty remains regarding the best roofing material for improving subsurface cooling during hot summers in temperate continental arid climates. Comparative studies on different roof materials under various climatic conditions are essential to determine the most effective heat mitigation strategies for arid oasis cities. We present a conceptual model to examine the relationship between roofing materials and their thermal mitigation capabilities in arid regions during hot summers, while assessing the influence of climate factors on their cooling performance. An experiment in Urumqi evaluated the subsurface heat mitigation capabilities of four roofing materials: white polymer materials (WPM), sod (SOD), asphalt (ASP), and solar photovoltaic panels (SPP). The results showed that the WPM provided the most effective subsurface cooling. Compared with SOD, ASP, and SPP, WPM showed the lowest subsurface temperature. Notably, the subsurface temperature of the WPM was minimally affected by climatic factors and showed no correlation with solar radiation intensity, precipitation, and cloudiness (P > 0.05), highlighting its superior cooling performance. WPM roofs are recommended for heat mitigation during hot summers in arid oasis cities owing to their low maintenance costs, ecological benefits, and superior cooling performance. This study highlights the subsurface cooling capabilities of various roofing materials and their interaction with climatic factors and provides valuable insights for heat mitigation strategies in arid regions.