Abstract Classical plant functional traits, often limited by intercorrelation and incomplete capture of dynamic variation, are insufficient for fully predicting ecological responses to environmental change. Quantifying independent functional dimensions, particularly those reflecting molecular and biochemical processes, is therefore essential for a comprehensive understanding of plant ecology. We adapted the well‐established community‐weighted mean (CWM) concept from ecology to metabolomic data, developing a framework to quantify metabolic functional traits based on the intrinsic chemical properties of metabolites. We applied this framework to root exudate metabolomics of Haloxylon ammodendron seedlings undergoing intraspecific competition. Our results show that intraspecific competition significantly altered the root exudate metabolome composition. We characterised the chemical space of identified metabolites using molecular descriptors, revealing three core dimensions of variation: molecular size/hydrogen bonding, acidity/structural complexity and hydrophobicity/saturation. Plant metabolic functional traits, quantified as CWMs of these chemical properties, varied significantly with competitive interaction, exhibiting distinct adaptive patterns across treatments, ranging from investment in defence/allelopathy to nutrient mobilisation or aggressive nutrient acquisition. Crucially, correlation analyses showed no significant relationship between metabolic CWMs and classical traits, and integrated principal component analysis further revealed their orthogonal separation in multivariate space. Synthesis : These findings demonstrate that metabolic CWMs represent a novel, independent functional dimension. This highlights the power and potential of integrating molecular‐level functional traits to enhance our understanding of plant ecological strategies and phenotypic plasticity, particularly in capturing intraspecific variation.

A study on the sources, bioconcentration, and translocation of heavy metals in Haloxylon ammodendron in the Eastern Junggar Coalfield, Xinjiang, China, was conducted and evaluated. The quantities of Pb, Cd, and Cr were 1.2, 22.5, and 1.9 times higher than the baseline values of Xinjiang soils, respectively. The mean concentrations of these heavy metals in the rhizosphere soil of Haloxylon ammodendron were 48.81, 17.74, 93.25, 3.32, 29.05, and 26.95 mg/kg. The exceedance rates for Cd, Cr, and Pb in bare soil were 100%, 99.03%, and 75.73%, respectively, indicating significant accumulation of heavy metals, with Cd demonstrating the highest enrichment degree. Most sampling sites showed moderate pollution according to the Pollution Load Index (PLI). Meanwhile, the Pollution Index (PN) indicated elevated pollution levels at all the sampling sites, with Cr identified as the first contaminant. The absolute principal component score–multiple linear regression (APCS-MLR) model revealed three principal sources of heavy metal pollutants in soil: 44.2% from natural processes and mining activities, 22.7% from industrial coal combustion and sewage, and 33.1% of undetermined origins. The bioconcentration factors (BCFs) and translocation factors (TFs) revealed Haloxylon ammodendron to have clear accumulation and translocation abilities with respect to these heavy metals. The fuzzy membership function showed that the overall assessment score for Haloxylon ammodendron was 9.1325, indicating the substantial remediation potential of Haloxylon ammodendron for heavy metal pollutants, especially for Cd. Furthermore, Haloxylon ammodendron demonstrated substantial Pb and Cr accumulation and remediation ability. Haloxylon ammodendron exhibited remarkable heavy metal accumulation and translocation abilities, making it a suitable tool for phytoremediation in the study area. The findings of this study will prove useful in promoting and implementing sustainable mining practices and safeguarding regional ecological security and may contribute to advancing local ecological conservation and social economic development.

Haloxylon ammodendron plantations constitute a dominant vegetation component of the desert–oasis ecotone in the arid and semi-arid regions of northwest China, playing a critical role in maintaining oasis stability and ecological security. However, the effects of converting natural desert ecosystems into plantations on the soil food webs of arthropods remain poorly understood, particularly with respect to how these effects vary across plantation age. To address this knowledge gap, we conducted a field investigation in the desert–oasis ecotone of the middle reaches of the Hexi Corridor, Gansu Province. Using pitfall trapping, we sampled two key arthropod taxa (arachnids and soil mesofauna) from control areas (natural deserts) and H. ammodendron plantations representing different ages (young and old). The results indicated that both young and old plantations were associated with significantly higher abundance and richness of arachnids, soil mesofauna, mites, and springtails compared with natural deserts, with springtail richness exhibiting a further significant increase in old plantations. Arachnid responses to plantation conversion were strongly structured by body size. Medium arachnid abundance increased in both young and old plantations, whereas large arachnid abundance increased only in young plantations and declined in older ones. In contrast, small arachnid abundance exhibited significant increases exclusively in old plantations. In addition, relationships between arachnid, mite and springtail abundance varied with plantation age: the ratio of large arachnids to mites and springtails declined significantly in old plantations relative to young ones, while the corresponding ratio for small arachnids showed an opposite pattern. Variations in soil mesofauna community composition were primarily explained by shrub cover, herbaceous cover, coarse sand proportion, silt-clay content, and soil soluble salt, which together accounted for 48.9% of observed variation. For arachnids, soil mesofauna as a food resource significantly enhanced abundance and richness. Moreover, shrub cover and silt-clay content were also drivers of arachnid community variation, jointly explaining 6.7% of variance. Overall, the establishment of H. ammodendron plantations promoted the diversity of both arachnids and soil mesofauna, but their relationships shifted dynamically with plantation age, leading to a reorganization of detrital food web structure and functioning.

Plant growth-promoting endophytes (PGPE) in halophytes have the potential to enhance plant stress resistance and promote growth, demonstrating broad application prospects in agriculture. The culturable microorganisms inhabiting in halophytes and their potential roles in enhancing salt-stress resistance of crops remain limited. This study isolated culturable endophytic bacteria from the roots of two dominant desert halophytes, Haloxylon ammodendron and Halostachys caspica, determined their growth-promoting abilities, and evaluated their capability in improving wheat performance under salt stress. Five saline-alkali tolerant bacterial strains-identified as Priestia endophyticus (S1, Y5), Priestia licheniformis (S2), Streptomyces griseorubens (S7), and Nocardiopsis aegyptia (Y6)-were characterized. These bacterial strains exhibited robust survival in 1.4 mol/L NaCl and high-pH environments (pH > 11.0), while demonstrating multiple growth-promoting traits, including indole-3-acetic acid (IAA) production and inorganic phosphate solubilization. All of the five strains (except for S2) and mixed culture improved the germination potential at 100 mmol/L NaCl. The strains S7, Y5, and mixed culture significantly increased plant height, root length, above ground fresh and dry weight compared to 200 mmol/L NaCl stressed seedlings (200CK)(p < 0.05). Salt stress significantly decreased chlorophyll content by 25.82% and 34.06% under 100 and 200mmol/L NaCl in comparison to CK. Conversely, PGPE inoculation significantly promoted chlorophyll synthesis of seedlings under salt stress. PGPE inoculation reduced enzyme activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) relative to the salt stressed seedlings. All inoculation treatments significantly decreased SOD activity by 20.2%-34.62%, and POD activity by 30.79%-53.38%, relative to 200CK. These findings demonstrate that these strains isolated from halophytic plants exhibit positive effects in ameliorating salt stress and improving the growth of wheat seedlings, highlighting their potential for enhancing agricultural productivity in saline-alkali soils.

Haloxylon ammodendron, a keystone species forrestoring desert ecosystems, has extremely low seedling survival rates under natural conditions due to surface high-temperature and secondary drought stress. This study investigated the effects of heat priming on the tolerance of H. ammodendron seedlings to subsequent drought stress and the underlying molecular mechanisms. The results demonstrated that heat priming (37°C for 12h) significantly improved seedling survival under drought stress (simulated with 480 mmol·L⁻¹ sorbitol) and reduced cell mortality. Physiological analyses revealed that heat priming increased the activities of antioxidant enzymes (SOD, POD, and CAT) and the accumulation of proline and chlorophyll, albeit with aggravated membrane lipid peroxidation (elevated MDA content). Transcriptomic profiling revealed 909 heat-priming-specific differentially expressed genes (DEGs), which were predominantly enriched in plant‒pathogen interactions, the MAPK signaling pathway, and phenylpropanoid biosynthesis. Key genes such as WRKY24 and MAPK3 potentially mediate cross-regulation to reinforce stress memory. Furthermore, heat priming suppressed drought-induced excessive lignin accumulation, suggesting that cell wall remodeling contributes to drought tolerance. CONCLUSIONS: Collectively, heat priming activates oxidative defense, signal transduction, and metabolic reprogramming, thereby increasing cross-tolerance to secondary drought stress in H. ammodendron seedlings. These findings provide theoretical insights into its ecological adaptation and stress resistance.

Haloxylon ammodendron and Haloxylon persicum are ecologically and economically important drought-tolerant plants, often referred to as "desert guardians" owing to their remarkable abilities to withstand conditions of drought and salinity. We conducted a chromosome-level genome assembly using PacBio HiFi long-read sequences and Hi-C technology in order to gain a deeper understanding of their adaptive mechanisms and resource potential. The final assembled genome sizes were 2.32 Gb (contig N50 = 5.11 Mb; Scaffolds N50 = 257.59 Mb) for H. ammodendron and 1.32 Gb (contig N50 = 9.55 Mb; Scaffolds N50 = 143.67 Mb) for H. persicum, with 97.84% and 95.45% of the respective sequences anchored to nine pseudochromosomes. The BUSCO integrity scores were 88.40% and 84.00% for H. ammodendron and H. persicum, respectively. Gene annotation revealed that H. ammodendron contained 69,844 protein-coding genes, while H. persicum had 66,859 protein-coding genes, with repeat elements constituting 57.42% and 52.88% of their genomes, respectively. The reference genomes of Haloxylon serve as invaluable resources for exploring the ecological and economic significance of desert plants.

ABSTRACT Haloxylon ammodendron, the dominant shrub species in Junggar Basin of Xinjiang, plays a pivotal role in maintaining the stability of the basin’s community structure. The range of H. ammodendron in the Junggar Basin is contracting, with populations declining due to global environmental changes and human disturbances. This study evaluates the health of H. ammodendron shrubbery in the Junggar Basin through field surveys across five site conditions, employing a multi-level assessment system with six primary and 27 secondary indicators. Health Index (HI) model and various weighting methods were used to ensure robust plot assessments. The study yielded the following key findings: Among the 122 sample plots assessed, health statuses were classified as follows: unhealthy (32), severely sub-healthy (44), moderately sub-healthy (14), mildly sub-healthy (16), and healthy (16). The five site conditions ranked from highest to lowest health status are: semi-fixed sand dunes, fixed sand dunes, mobile sand dunes, gravelly Gobi desert, and rocky low mountains. The primary factors affecting the health of H. ammodendron shrubbery were identified as water table depth, the prevalence of pests, diseases, and rodents, and the level of human care.

The study examines the ecological and geographical characteristics of Astragalus ammodendron, a typical species of desert ecosystems in Central Asia. The species is distributed in Kazakhstan, Uzbekistan, Turkmenistan, and China, preferring sandy and clay deserts, where it forms stable phytocenoses. The aim of the study is to analyze the ecological and geographical plasticity of A. ammodendron, its adaptive mechanisms, and its role in ecosystem stabilization. The research employs route reconnaissance, ecological-systematic, and ecological-geographical methods. A comparative analysis of contemporary and historical herbarium data from collections in Kazakhstan, Russia, and Uzbekistan was conducted, along with cartographic modeling of the species’ range using QGIS 3.34. The obtained data confirm the species' drought resistance, its ability to stabilize sandy substrates, and its formation of specific communities with Haloxylon aphyllum, Calligonum leucocladum, and Artemisia terrae-albae. In some areas, population fragmentation has been observed due to anthropogenic factors, including livestock grazing and changes in the hydrological regime. This study contributes to understanding the ecological and geographical patterns of desert plants and their phytocenotic role. The practical significance of the results lies in their potential application for monitoring, conservation, and restoration of ecosystems undergoing degradation due to climate change and anthropogenic impact.

Haloxylon ammodendron, a keystone woody species, and its parasitic plant, Cistanche deserticola, play critical roles in sustaining arid ecosystems and supporting regional economies. However, their distribution is increasingly threatened by global climate change. Here, we propose a dual niche modeling framework that integrates climate and soil suitability layers using a multi-model ensemble approach combined with interpretable machine-learning techniques, specifically SHapley Additive exPlanations (SHAP). Using CMIP6 scenarios (SSP126, SSP245, and SSP585), we predicted the current and future potential habitats for both species. The results demonstrated that the ensemble models delivered robust performance, surpassing the accuracy of single-model predictions. Currently, suitable habitats are concentrated in northwestern China as well as parts of Mongolia and Kazakhstan. Under SSP585 (2081–2100), H. ammodendron habitats are projected to shrink by 56.2%, whereas C. deserticola is expected to lose more than 97% of its habitat, nearly disappearing from Central Asia. Key climatic drivers include temperature seasonality and precipitation patterns, whereas the soil water-holding capacity and gravel content significantly affect local suitability. Niche overlap analysis revealed a strong host dependency for C. deserticola. However, the climate–soil niche congruence is projected to decrease under future scenarios, indicating the potential risks of ecological decoupling. This integrative and interpretable approach offers a scalable tool for biodiversity assessment and provides actionable insights for conservation planning in climate-sensitive, arid ecosystems.

Perennial desert dominant species Haloxylon ammodendron exhibits three distinct morphological diaspores that differ in protein content among polymorphic fruits drives divergence in germination traits, likely forming a bet-hedging ecological adaptation strategy to cope with extreme environmental heterogeneity in desert ecosystems. Fruit polymorphism, the production of multiple fruit morphotypes within a species, is an adaptive bet-hedging strategy in variable environments. However, researches about perennial plant and the adaptive mechanisms are not well understood. Haloxylon ammodendron, a constructive desert shrub, exhibits three fruit morphotypes: YY (yellow wings with yellow pericarp), YP (yellow wings with pink pericarp), and PP (pink wings with pink pericarp). We investigated their ecophysiological and molecular mechanisms through germination assays under salt and drought stress, combined with proteomic analysis. YP consistently showed the highest germination percentage (GP) and germination rate index (GRI) under stress, while PP displayed well germination success under low salinity and well-watered conditions (GP = 32.7%, 36.7%; GRI = 0.018, 0.020), but significantly impaired viability under stress (GP = 12.7%, 12.0%; GRI = 0.006, 0.006). Proteomics identified 721 differentially accumulated proteins, with the most (662) between YP and PP, linked to stress response and germination. YP's high abundance of stress-resistant proteins enabled rapid germination, whereas PP's delayed germination aligns with a persistent seed bank strategy. This polymorphism promotes niche differentiation: YP ensures quick colonization, PP enhances long-term resilience, and YY offers an intermediate strategy. Our findings reveal molecular-ecological adaptations in H. ammodendron, aiding targeted germplasm use for desert restoration.

Haloxylon ammodendron is a highly salt-tolerant plant vital for desertification control in northwest China. Despite its ecological importance, the molecular mechanisms underlying its exceptional salt tolerance remain largely unexplored. This study aimed to elucidate the temporal dynamics of its transcriptomic responses to varying salinity levels. Temporal analysis revealed distinct gene expression patterns across low, medium, and high salt concentrations, with unique regulatory trends over time. Differential expression analysis identified 2,630 DEGs at 7days, 4,533 DEGs at 21days, and 2,581 DEGs at 30days, highlighting 21days as a critical period for salt response. WGCNA on 19,399 genes at day 21 revealed three modules (ME4-yellow, ME6-red, ME9-magenta) significantly associated with salt stress. These modules were enriched in genes involved in photosynthesis, amino acid metabolism, carbohydrate metabolism, and stress response pathways. Hub gene analysis identified ATPD and five sub-key genes as central regulators of the salt response network. This study provides the first comprehensive temporal transcriptomic analysis of H. ammodendron under varying salinity concentrations, revealing novel molecular insights into its salt adaptation mechanisms. The identified hub genes and pathways offer valuable targets for understanding extreme salt tolerance and enhancing desert reclamation efforts in arid regions.

Human activities have a profound impact on both the physical and chemical properties of soil, which, in turn, transform soil microbial ecosystems. Nonetheless, there is limited research on how opencast coal mining influences soil characteristics and microbial communities, particularly in the extreme climate of Xinjiang, China. Here, we investigated the rhizosphere soil of Haloxylon ammodendron at varying distances (500, 1,000, 1,500, and 2,000m) from the boundary of the Hongshaquan opencast coal mine in Xinjiang to explore the effects of mining on soil properties and microbial communities. The study revealed significant alterations in soil properties with increasing distance from the coal mine, including changes in particle size distribution, soil organic carbon (SOC), amorphous iron (Feo), and available potassium (AK). A notable positive correlation was observed between Feo and clay content, as well as between SOC and Feo. Additionally, the fungal community structure varied across different soil layers due to mining activities, with the complexity of fungal networks showing a decreasing trend as the distance from the mine increased. Partial least squares path modeling (PLS-PM) further indicated that changes in distance and soil depth from the mine affected the clay content, leading to alterations in Feo. These changes subsequently impacted fungal diversity through modifications in SOC. In conclusion, coal mining activities directly influenced soil clay content, triggering a cascade of changes in other soil properties, ultimately altering fungal diversity. This study offered new insights into the ecological restoration efforts required for regions affected by opencast coal mining.

Haloxylon ammodendron plantations: enhancing multi-trophic arthropod diversity and soil multifunctionality in arid deserts.

Metabolic and antioxidant responses drive Haloxylon ammodendron’s adaptation to drip irrigation with saline and freshwater in saline-alkali soils

ABSTRACTIn desert regions, precipitation is one of the significant water sources and a key driver of ecohydrological processes over a range of spatiotemporal scales. When precipitation infiltration was combined with the original soil water, the soil water and plant water use will experience significant dynamic changes, which play an important role in the stability and sustainability of the artificial vegetation. Therefore, soil water dynamics and water use strategies of Haloxylon ammodendron were studied by the hydrogen and oxygen stable isotope technique in this study. The results showed that precipitation in the desert soil was mainly in the form of piston flow, and the precipitation that led to the significant increase of infiltration and recharge was different in different precipitation events. The precipitation of 12.8 and 19.6 mm can make the surface soil water sufficient and continue to penetrate into the deep soil, and the duration of soil water response and the recharge depth were much longer and deeper than those for 4.4 and 7.8 mm events. In addition, the H. ammodendron mainly relied on stable and abundant deep soil water and groundwater. The water use source of H. ammodendron showed no significant response to 4.4 and 7.8 mm precipitation. However, a significant difference in water source proportion occurred before and after 19.6 mm of precipitation. The use proportion of shallow soil water increased from 10.7% to 24.2%, while that of groundwater decreased from 48.8% to 23.2%. Therefore, we concluded that precipitation levels have a major impact on soil water at various depths; in particular, heavy precipitation has a significant impact on deep soil water that deeply controlled the survival of the H. ammodendron plantation. These results offer an essential theoretical foundation for vegetation restoration and sustainability in arid regions.

A chromosome-level genome assembly of Cistanche deserticola provides insights into its evolution and molecular mechanisms of parasitism.

Long-term impact of Haloxylon ammodendron plantations on the trophic structure of ground arthropods in a desert–oasis ecotone

Restoration status of 38-year-old Haloxylon ammodendron plantations without irrigation under different catchment afforestation models

Introduction: This study investigated the phytoremediation potential of Atriplex canescens, Haloxylon aphyllum, and Nitraria schoberi for decontaminating soil polluted with radioactive elements. Materials and Methods: Contaminated soil was collected from a uranium mine site. Compost and sawdust were used as soil amendments. Radionuclide activities and concentrations were determined using gamma spectrometry and ICP-MS. Results: H. aphyllum demonstrated the highest uptake of radioactive elements, accumulating 58 mg.kg-1 of Th-232 and 28.08 mg.kg-1 of U-238, respectively. Considering their initial concentrations, the thorium removal efficiency was higher than that of uranium, with a maximum of 85% for Th-232 achieved by H. aphyllum. Plant roots accumulated higher concentrations of radionuclides than the stems. A comparison of phytoremediation factors (TF, BAF, and BCF) indicated that H. aphyllum had a greater stabilization potential than the other two species. Furthermore, phytoextraction was identified as the dominant remediation mechanism. Conclusion: Compost application enhanced the phytostabilization potential of all three plants (e.g., as indicated by the increase in BCF, which reached a maximum of 0.45 for H. aphyllum). In contrast, sawdust had an inhibitory effect, likely due to the disruption of the C/N ratio, which prevented plant growth. H. aphyllum showed significant potential for radioactive soil rehabilitation, particularly when it was amended with compost.

Leaves constitute a vital bottleneck in whole-plant water transport, and their water strategies are key determinants of plant competition and productivity. Nonetheless, our knowledge of leaf water strategies predominantly stems from single perspectives (i.e., hydraulic, stomatal or economic traits), severely limiting our capacity to comprehensively predict plant vulnerability and sustainability, especially under drought-stress conditions. Here, we examined the leaf hydraulic, stomatal and economic traits of three coexisting shrub species (i.e., Haloxylon ammodendron (C.A. Mey.) Bunge., Calligonum mongolicum Turcz. and Nitraria sphaerocarpa Maxim.) in the Badain Jaran desert-oasis ecotone to comprehensively evaluate their water strategies and drought adaptation mechanisms. The results demonstrated that these three shrubs exhibited significant differences in leaf hydraulic vulnerability, osmoregulatory capacity, stomatal behavior and economic traits. Nonetheless, these traits remain tightly related to guarantee their survival. Interestingly, two distinct interaction mechanisms between stomatal and hydraulic regulation were identified among the three shrubs with varying stomatal sensitivity. Specifically, N. sphaerocarpa and H. ammodendron employed relatively lower isohydric stomatal behavior, characterized by a synergistic decrease in vapor-phase water loss as liquid-phase water transport decreased during severe atmospheric drought. Conversely, C. mongolicum adopted higher isohydric stomatal behavior, rapidly reducing vapor-phase water loss during initial drought stress to compensate for its more vulnerable liquid-phase water transport system. Notably, all three shrubs presented risky leaf water strategies with negative hydraulic safety margins. Among them, the hydraulic dysfunction risk was lowest for C. mongolicum, followed by N. sphaerocarpa and H. ammodendron. Overall, our findings are anticipated to offer valuable insights for afforestation initiatives and ecological conservation efforts in desert-oasis ecotones that function as critical shelterbelts.