BACKGROUND AND AMIS:Volatile organic compounds (VOCs) mediated plant-plant communication is a crucial mechanism enhancing plants' ecological fitness, yet its role in desert mosses remains unclear. METHODS:We analyzed VOCs emission from Didymodon vinealis and Syntrichia caninervis and simulated their intraspecific airborne communication under dehydration-rehydration cycles. The VOCs emitters and receivers were subsequently subjected to light rainfall events, and soluble sugar, starch, chlorophyll, and superoxide dismutase activity (SOD) were measured to assess stress resistance. RESULTS:Gas chromatography-mass spectrometry identified 333 compounds, including isoprene, terpenes, ketones, and aromatic hydrocarbons, whose emission profiles varied significantly with precipitation changes. Upon perceiving altered VOCs signals the two mosses species exhibited distinct physiological responses. D. vinealis-receivers showed higher soluble sugar and non-structure carbon (NSC) content than emitters and controls (CK, receivers that exposed to VOCs released by emitters that had not undergone hydration-dehydration cycles), whereas S. caninervis-receivers demonstrated increased NSC levels but no significant differences in soluble sugar or SOD activity compared to emitters. Both species maintained these enhanced physiological traits for 1∼7 days following 0mm rainfall conditions. Under single light rainfall event, D. vinealis-receivers exhibited higher NSC content or SOD activity across 0-1mm rainfall events, while S. caninervis-receivers only showed elevated SOD activity only under 0 and 0.2 mm rainfall. CONCLUSION:Our findings demonstrate that VOCs mediate intraspecific communication in desert mosses and enhance physiological resilience to fluctuating hydration, providing new insight into their adaptive strategies and evolutionary trajectories in arid ecosystems.

Biological soil crusts (BSCs) are important components of dryland soils that influence nutrient cycling and soil microbial activity, yet the depth-dependent responses of BSCs-associated microbial communities to long-term nitrogen (N) enrichment remain insufficiently understood. Here, we conducted a 13-year in situ N addition experiment (0–3.0 g N m⁻² yr⁻¹) in the Gurbantunggut Desert to compare bacterial and fungal communities between the moss BSCs layer and the underlying sub-biocrust soil (0–5 cm). Microbial communities exhibited pronounced vertical differentiation, with higher bacterial and fungal biomass and higher bacterial diversity in the BSCs layer than in sub-biocrust soils. Long-term N addition produced strong depth- and taxon-dependent responses. In the BSCs layer, bacterial communities were more sensitive to N addition than fungal communities, showing reduced niche breadth and migration-related parameters and a shift in community assembly from stochastic toward deterministic processes, accompanied by decreased co-occurrence network robustness. In contrast, fungal communities in sub-biocrust soils responded more strongly than bacteria, where N addition similarly promoted deterministic succession and reduced network robustness. Structural equation modeling further indicated that N influenced microbial communities in the BSCs layer via both direct effects and indirect effects mediated by changes in soil nutrient availability, whereas responses in sub-biocrust soils were entirely nutrient-mediated. Overall, these results demonstrate that long-term N addition induces depth-dependent changes in microbial community assembly and association network structure in BSCs-associated soils, highlighting the importance of accounting for soil depth and microhabitat heterogeneity when evaluating the impacts of N enrichment on dryland soil microbial communities and nutrient cycling.

Aridity represents a primary driver of desertification in semiarid and arid ecosystems, where soil microbial communities play pivotal roles in sustaining dryland ecosystem functions. However, the mechanisms by which biocrust-forming mosses influence bacterial community distribution and assembly under varying levels of aridity remain insufficiently resolved. In this study, we investigated the effects of moss crusts on bacterial community diversity and assembly processes across arid and semiarid regions of northern China using targeted metagenomic analysis of the 16S rRNA gene. Our results show that moss crusts significantly enhance bacterial alpha-diversity while reducing beta-diversity relative to adjacent bare soil across all sampled regions. Moreover, bacterial communities associated with moss crusts exhibit a stronger propensity for stochastic assembly processes compared to those in bare soils, and display attenuated spatial turnover along the aridity gradient. In contrast, bacterial assembly in bare soils is jointly constrained by aridity and soil nutrient availability, whereas moss crust-associated communities are predominantly influenced by aridity. Notably, moss crusts elevate the aridity threshold under which bacterial community assembly transitions from stochastic to deterministic dominance, from 0.83 to 0.91, thereby extending the range of aridity conditions under which stochastic processes prevail. These findings highlight the critical role of moss crusts in enhancing the functional stability of desert ecosystems under drought stress, through modulation of regional-scale bacterial diversity, heterogeneity, and assembly dynamics, and support their strategic application in climate-resilient ecological restoration.

Soil microbial entropy (qMB) is the proportion of soil elements within microbial biomass, reflecting microbial resource support capacity and nutrient use efficiency. Its spatial pattern provides the basis for assessing soil ecological functions. However, existing studies are largely limited to local scales and lack comprehensive, high-resolution national predictions, with insufficient understanding of the multifactor-driven mechanisms and future dynamics under climate change. In this study, we collected microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP) data from 1,288 published studies across China and calculated the corresponding qMBC, qMBN, and qMBP. We compared five machine learning models and selected the random forest model with the best predictive performance to map the spatial distribution of qMB. Subsequently, we explored the main drivers of its spatial variation and projected future trends. The results: (1) The mean values of qMBC, qMBN, and qMBP were 2.93

In desert ecosystems, biological soil crusts (biocrusts) play a crucial role in regulating soil nutrient dynamics and plant productivity. However, their cascading effects on aboveground biomass (AGB) mediated through soil-plant-microbe interactions remain poorly understood. To address this gap, we conducted a field experiment in the Gurbantunggut Desert of Central Asia, focusing on Erodium oxyrrhynchum, a dominant ephemeral species. We compared biocrust successional stages (from bare sand to moss crust) and ephemeral plant germination seasons (spring vs. autumn), assessing soil properties, plant traits, and phyllosphere microbial communities. Significant differences in leaf traits and AGB were observed between spring- and autumn-germinated plants across biocrust successional stages. Autumn-germinated plants exhibited higher AGB and more resource-acquisitive traits, whereas spring-germinated plants showed stronger stress tolerance but reduced AGB. AGB declined along the biocrust successional gradient (bare sand > algal crust > lichen crust > moss crust). Structural equation modeling revealed that soil moisture and nutrient availability were the dominant drivers of AGB, followed by phyllosphere microbial composition and plant traits. Biocrusts influenced plant biomass primarily through bacteria-mediated pathways that modified soil conditions. These findings highlight a trade-off between biocrusts-driven nutrient enrichment and water limitation, that collectively shape desert ecosystem productivity. They also provide a mechanistic foundation for predicting ecosystem responses to environmental change and for developing effective restoration strategies in arid regions.

Abstract Non-structural carbohydrates (NSC) are plant nutrients that not only supply carbon sources during environmental stress, but also reflect the adaptive strategies of plants to external conditions. Chenopodioideae plants are among the most species-rich and widely distributed flora in Central Asia deserts, playing an indispensable role in maintaining ecosystem stability. Current understanding remains limited regarding NSC allocation and utilization strategies across organs and life forms of Chenopodioideae plants in arid Central Asia. This study examined variation in NSC and its components in leaves and stems of Chenopodioideae plants across life forms in northwestern China, and explored their relationships with environmental and driving factors. Results showed significantly higher total NSC concentration in leaves than stems across life forms, with marked variations in starch, soluble sugars, fructose, sucrose and sugar-starch ratios among life forms. Allometric relationships were observed in NSC and its components between organs, with stems exhibiting higher accumulation rates of soluble sugars, fructose, and sucrose than leaves. Climate predominantly influenced NSC variations across plant organs at the transect scale, whereas geographic and soil factors exerted stronger influences on NSC and its components in different organs of small trees. Structural equation modeling revealed that climate, plant organs, and life forms collectively regulate NSC concentration, while climate additionally influences NSC levels indirectly via soil mediation. These findings not only advance our understanding of survival strategies of Chenopodioideae plants in central Asia, but also establish a theoretical framework for deciphering desert plants’ roles in carbon cycling.

Chenopodioideae plants are dominant components of desert ecosystems in arid regions of China and Central Asia and play key roles in maintaining ecosystem stability, while also providing valuable systems for understanding evolutionary and environmental adaptations of desert vegetation. However, at the family level, stoichiometric patterns across functional groups and plant organs in Chenopodioideae species remain poorly understood. We investigated 68 desert sites along a > 2000 km desert transect in northwestern China and collected leaf and stem samples from 39 Chenopodioideae species. After data preprocessing and standardization, 167 independent leaf units and 161 independent stem units were retained for subsequent analyses. We examined variation patterns and environmental drivers of nitrogen (N), phosphorus (P), and potassium (K) across functional groups (C3 vs. C4 plants; trees, shrubs, and herbs) and organs (stems and leaves) at the community level. Compared with global and national datasets, Chenopodioideae plants exhibited lower N concentrations (8.846 mg g− 1 in stems and 15.768 mg g− 1 in leaves) but higher P (1.235 mg g− 1 and 1.497 mg g− 1) and K concentrations (23.758 mg g− 1 and 27.656 mg g− 1), suggesting potential nitrogen limitation. Significant differences in nutrient concentrations were observed among most functional groups and organs. Based on community-weighted means, leaves exhibited consistently lower P-K scaling exponents than stems across functional groups, suggesting enhanced K-related stress resistance. Stem and leaf N, P, N: P, and P: K exhibited homeostatic or strictly homeostatic patterns, supporting the “Stability of Limiting Elements Hypothesis”. Nutrient traits showed divergent responses along latitude, longitude, and aridity gradients, reflecting diverse adaptive strategies. Environmental drivers varied among traits and organs. Soil, climatic, and geographical factors jointly regulated nutrient concentrations and ratios through interacting pathways, with soil factors generally exerting stronger relative influences. Overall, our findings reveal differentiated yet partially convergent stoichiometric strategies among functional groups and organs, highlighting adaptive nutrient regulation mechanisms in arid desert ecosystems.

Understanding the mechanisms of biodiversity-driven functional stability is crucial for predicting ecological resilience. For desert ephemerals, whose aboveground biomass (AGB) is highly transient and volatile, the buffering mechanisms that sustain community stability under extreme environments have yet to be fully elucidated. In this study, four years of field observations (2021–2024) from the Gurbantunggut Desert were utilised. We used linear mixed-effects models (LMM), structural equation modelling (SEM), and Lotka–Volterra simulations to analyse AGB stability. The results showed that conservative traits drove AGB stability more strongly than acquisitive traits. Specifically, community-weighted mean leaf carbon (CWM.C) and root diameter (CWM.RD) provided the highest explanatory power. Mean annual precipitation (MAP) and species richness (SR) were the primary drivers, explaining 30.71% and 28.28% of the variance. In contrast, species evenness (Pielou) had a weak and direct negative effect (4.32%). SEM revealed that SR enhanced stability by increasing CWM.C and community-weighted mean specific leaf area (CWM.SLA), which subsequently drove stability (0.28 and 0.19). Furthermore, the stabilizing effect of species asynchrony (0.11) depended fundamentally on conservative root traits (CWM.RD, 0.17). Long-term simulations also confirmed that the facilitative influences of SR and conservative traits on stability persist, while competitive disturbances linked to acquisitive traits systematically diminish over time. These findings demonstrate that biodiversity enhances stability through two pathways. First, increased richness directly promotes trait-mediated asynchronous responses. Second, the selection of conservative traits establishes biological buffers against biomass fluctuations. This study highlights the synergistic roles of species richness and conservative functional traits in maintaining the stability of ephemeral plant communities, thereby advancing the theoretical understanding of biodiversity–stability relationships in desert ecosystems.

Soil microbial biomass is a sensitive indicator of soil nutrient dynamics and biogeochemical processes. Fungi, as an integral component of microbial communities, play a dominant role in critical biogeochemical functions. Although the fundamental role of fungi in global carbon and nutrient cycles is widely recognized, their biogeographic distribution remains poorly understood. Therefore, systematically mapping the spatial distribution of global fungal biomass and its dominant drivers provides an essential scientific basis for understanding terrestrial ecosystem responses to global change. This study integrates observational data of phospholipid fatty acid (PLFA) from 4,502 global sampling sites with 15 environmental factors, including space, climate, soil, and plants attributes. Using the XGBoost model with optimal predictive performance, we estimated fungal biomass carbon (FBC) stock at 0–30 cm soil depth (topsoil) and generated a high-resolution spatial distribution map. The results: (1) Global FBC stock in topsoil was estimated to be 14.07 Pg C (9.77–18.25, mean with 25% and 75% quantiles). Spatially, FBC stock was highest in high-latitude forests and peatlands in the northern hemisphere and lowest in mid-latitude desert regions. (2) Climate is the strongest predictor within the model framework regulating spatial FBC variability: negative correlation with mean annual temperature (MAT), positive with mean annual precipitation (MAP). (3) FBC exhibits nonlinear responses to environmental factors, with critical threshold values at: MAT (6.21 °C), soil pH (5.20), aridity index (0.95), and MAP (66.10 cm). (4) Sensitivity analysis indicates that under a 20% increase in future precipitation, global FBC stocks will significantly rise (p < 0.01), with the primary increase occurring in mid-latitude desert regions. The results not only provide critical parameters for global soil carbon pool estimation and enhance understanding of fungal-driven carbon cycling mechanisms, but also establish a basis for predicting soil carbon sink dynamics under climate change.

Winter snow cover serves as a crucial water resource for plant growth in water-limited desert ecosystems. However, the response of soil physicochemical properties and soil multifunctionality to changes in snow cover remains unclear. We manipulated snow depth at four levels: snow removal (SR), ambient snow, double snow (DS), and triple snow (TS) in the Gurbantunggut Desert starting in 2017. Soil samples were collected in March, May, August, and November of 2018. Results indicated a significant increase in soil water content in March with increased snow depth, and an increase in soil pH throughout the year. Additionally, increased snow cover accelerated the mineralization of nitrogen and phosphorus, enhancing available nitrogen and phosphorus content in the soil and further exacerbating nitrogen limitation in desert areas. Concurrently, soil multifunctionality changed and exhibited a synergistic trend with snow cover variation throughout the year. Structural equation modeling revealed that species richness and soil pH were key environmental factors regulating soil multifunctionality, with soil pH having a significant positive effect. These findings suggested that snow-cover depth influences the dynamics of soil physicochemical properties and soil multifunctionality in the Gurbantunggut desert. This study provides insights into how changes in winter snow cover depth affect soil nutrients and ecosystem functions in temperate desert ecosystems and offers predictions for the evolution of desert ecosystems under global change.

Drivers of non-native plant success in drylands are poorly understood. Here we identify functional differences between dryland native and non-native perennial plants and assess how biotic, abiotic and anthropogenic factors shape the success of the latter. On the basis of plant community and functional trait data from 98 sites across 25 countries, we report a total of 41 non-native plant species at 31 sites. Non-natives tend towards faster growth strategies than natives. Non-native plant richness is higher at sites with greater grazing pressure and under environmental conditions associated with higher soil fertility, decomposition and fungal richness-conditions that tend to occur in less arid regions-and lower where native plant and herbivore richness are greater. Non-native plant cover correlates positively with grazing pressure and negatively with native plant richness. Taken together, our results suggest that non-native plant success in drylands is facilitated when high grazing pressure coincides with elevated resource availability. Such context-dependence of non-native plant success and linkages with native plant and herbivore diversity highlight the need for managing grazing and conserving biodiversity across the world's drylands.

Soil total phosphorus (STP) is defined as the entirety of phosphorus present in the soil, constituted by both organic and inorganic fractions. STP is an essential element for maintaining ecosystem productivity and nutrient balance. However, due to the multiple impacts of climate change and intensified anthropogenic disturbances, the spatial distribution, drivers, and future trends of STP in the drylands of China are still unclear. This limits the precise management of soil P resources and sustainable regional development. In this study, based on the STP concentration data of 1108 sample sites, we compared the predictive performance of five machine learning models, selected the eXtreme Gradient Boosting model with superior predictive performance, estimated the STP stocks, mapped their spatial distribution, clarified the main drivers, and predicted future trends at the 0- to 100-cm soil depths. The results were as follows: (1) STP stocks at 0- to 30-cm and 30- to 100-cm depths were estimated to be 1.59 +/- 0.50 and 3.58 +/- 1.24 Pg, respectively. Among them, grassland STP stocks are the highest and shrub STP stocks are the lowest. (2) The spatial distribution of STP at 0-30 cm was primarily driven by climate, specifically mean annual temperature, whereas at 30-100 cm, it was primarily driven by microbial factors, specifically microbial biomass P. (3) Under future IPCC's Shared Socioeconomic Pathways, STP stocks all showed an increasing trend. The results help to understand how drylands respond to global changes, which is of great significance to the stability of terrestrial ecosystems and the sustainable use of P, and provide data support for regional soil fertility regulation.

The issue of desertification and the consequent soil erosion is a prominent global environmental concern, especially in dryland regions. Biological soil crusts (biocrusts) are crucial for enhancing the ability of soil to resist erosion; however, the underlying microbial enzymatic mechanisms are still poorly understood. In this study, samples of biocrusts (cyanobacterial crusts and moss crusts) from the Gurbantunggut Desert were collected to explore the function of carbonic anhydrases (CAs) in enhancing soil shear strength. The findings revealed that biocrust development significantly enhanced soil shear strength, especially in moss crusts. Variations in shear strength were strongly correlated with CA activity and bacterial composition. Biocrust development also significantly enhanced CA activity, demonstrating a positive correlation with shear strength. In line with the changes in shear strength and CA activity, bacterial abundance also increased in biocrusts, with Bacilli and Bacteroidia significantly contributing to CA secretion and promoting soil shear strength. Moreover, three Bacilli strains capable of producing CAs were isolated from biocrusts. Further data from scanning electron microscopy verified that the carbonate crystals induced by these bacterial CAs can effectively bind sand particles, thereby significantly enhancing the shear strength of the sand. In summary, the current study provides robust evidence that supports the role of CAs in enhancing shear strength during biocrust development in dryland ecosystems. These results offer a unique enzymological perspective for understanding the contribution of biocrusts to mitigating soil erosion and highlight the significance of species selection in biocrust restoration and desertification control.

In drylands, biocrusts function as essential components of the nitrogen cycle and display pronounced sensitivity to external nitrogen inputs. Episodic rainfall events can mobilize dry-deposited nitrogen into shortterm pulse that influences nitrogen retention and transformation. However, the effects of short-term nitrogen pulse, commonly encountered in drylands, on biocrust nitrogen dynamics remain poorly understood. This study simulates rainfall-driven short-term nitrogen pulse to examine how varying pulse concentrations impact biocrusts nitrogen fixation, ammonia oxidation, and overall nitrogen balance under conditions of intensified nitrogen deposition after a 13-year nitrogen addition experiment in Gurbantunggut Desert. The nitrogen pulse sharply disrupted biocrusts’ nitrogen cycling. Both nitrogen fixation and ammonia oxidation rates declined precipitously immediately after the pulse. However, within 14–21 days, these rates rebounded to or even surpassed pre-pulse levels. This pattern reflects the biocrusts’ acute sensitivity to nitrogen perturbations, as well as their ecological resilience. Over 21 days, cumulative nitrogen fixation decreased by 47

Malus sieversii, a Tertiary relict and primary progenitor of the cultivated apple, is experiencing severe habitat degradation in China's Tianshan Mountains. To understand how soil ecosystem functions respond to tree vigor decline, we monitored surface soils beneath the canopy of wild apple trees monthly from April to October. Trees were classified into three vigor classes based on the percentage of dead branches: Vigor Class I (<20%), Vigor Class II (40-60%), and Vigor Class III (>80%). Soil multifunctionality (SMF) and temporal variability of nutrients (TVN) were derived from seven key nutrient indicators. Soils under Vigor Class II trees exhibited the lowest SMF and highest TVN, indicating maximal functional instability during intermediate degradation. While SMF peaked and TVN reached its seasonal minimum in October, Vigor Class II showed a consistent decline in TVN over time, unlike the irregular fluctuations in Vigor Classes I and III. A significant negative SMF-TVN correlation in Vigor Classes II and III suggests a trade-off between functionality and stability. Partial least squares path modeling revealed that soil organic carbon, total nitrogen, and total phosphorus were the dominant direct driver of both SMF and TVN, with climate exerting no significant direct effects once tree vigor and soil conditions were accounted for. These results suggest that Vigor Class II represents a critical early-warning stage: soil functional capacity begins to deteriorate before visible signs of severe tree decline or mortality. Targeted ecological restoration of Vigor Class II trees is essential to prevent irreversible ecosystem degradation. Therefore, while continued protection of healthy Vigor Class I trees remains essential, conservation efforts should place greater emphasis on restoring Vigor Class II trees to disrupt degradation feedbacks before irreversible ecosystem decline occurs.

Soil multifunctionality (SMF) and the soil quality index (SQI) are essential indicators of soil function, productivity, and health. Additionally, the spatial variability of soil multifunctionality (SVM) signifies soil heterogeneity. Biological soil crusts (Biocrusts) can affect these indicators. However, there is little information about the role of biocrusts in regulating the response of multiple ecosystem functions to climate change. We evaluated the relative importance of climate, soil environment, and biocrusts variables as drivers of SMF, SQI, and SVM at 74 sites in the Gurbantunggut Desert. Soil SMF, and SQI increase with the coverage of lichen and moss crust. Biocrusts index, SMF and SQI increase with an increase in the mean annual temperature. Biocrusts index, SMF and SQI increase first with an increase in mean annual precipitation (MAP)< 163 mm and then decrease. SVM display a significant decreasing trend with the increase of MAP. The structural equation model (SEM) demonstrate that the spatial distribution can significantly influence the biocrusts, soil SQI and SVM. Biocrusts has a significant positive influence on soil SMF (0.47)and SQI (0.31). Soil SMF has a significant negative effect on SVM (-0.50), and SQI (0.59) has a significant positive effect. We provide the first quantitative evidence that biocrust type and a 163 mm precipitation threshold govern SMF through opposing direct vs. indirect temperature pathways, offering a predictive rule-of-thumb for dryland management under climate change. The findings contribute decidedly to our understanding of the patterns and mechanisms driving SMF, SQI, and SVM in drylands, which is important for predicting changes in ecosystem function under climate change.

Grassland ecosystems play a crucial role in the global carbon cycle, yet the spatial patterns and drivers of soil organic carbon density (SOCD) across aridity gradients remain insufficiently understood. Here, we used the Carbon Density Dataset of China's Terrestrial Ecosystems (2010s) and applied random forest models to simulate SOCD at two soil depths (SOCD0-20 cm and SOCD0-100 cm) in arid and humid grasslands. We further quantified the contributions of environmental drivers and projected future SOCD dynamics under Shared Socioeconomic Pathways (SSPs). Results showed that SOCD was lower in arid than in humid regions, but due to their vast extent, arid regions contained larger total soil carbon stocks. The 0-20 cm layer accounted for approximately 50% of the SOCD in the 0-100 cm profile. In arid regions, SOCD0-20 cm was mainly controlled by mean annual temperature and soil moisture, while SOCD0-100 cm depended on clay content and total nitrogen. In humid regions, SOCD0-20 cm was strongly influenced by temperature and NDVI, whereas SOCD0-100 cm was regulated by clay and nitrogen. Under future SSP scenarios, SOCD is projected to decline in arid regions but increase in humid regions, indicating an enhanced carbon sink potential. SOCD0-20 cm showed higher variability and lower stability than SOCD0-100 cm. These findings clarify the spatial heterogeneity and depth-dependent controls of grassland SOCD and provide a scientific basis for region-specific soil carbon management, contributing to China's "dual carbon" goals and sustainable grassland policies.

Calligonum species are widely distributed across the arid desert belt stretching from North Africa to Central Asia. Their leaves are nearly fully degraded, and photosynthetic activity is predominantly undertaken by assimilative branches (ABs). Remarkably, Calligonum represents the only known lineage within the family Polygonaceae to exhibit the C4 photosynthetic pathway. To date, on the regional scale, the nutrient resorption patterns of ABs of different Calligonum species are still unclear. We investigated three representative species from distinct taxonomic sections native to the Junggar Desert of northwestern China: C. mongolicum (CM; Sect. Medusa), C. leucocladum (CL; Sect. Pterococcus), and C. junceum (CJ; Sect. Calliphysa). Green ABs and AB litters were collected during the summer and autumn, respectively, to assess interspecific differences in nitrogen (N), phosphorus (P), and potassium (K) resorption efficiencies (NRE, PRE, and KRE, respectively), and explore their stoichiometric relationships, variation patterns, and the environmental influences. Across all species, the nutrient resorption efficiencies (NuREs) followed the order: KRE (65.03% ± 0.57%) > PRE (53.57% ± 0.48%) > NRE (23.36% ± 0.70%). Among the three taxa, CM exhibited the highest NRE (29.20% ± 1.24%) and PRE (62.44% ± 0.45%), whereas KRE was lowest in CJ (57.41% ± 1.41%). All three species exhibited a scaling relationship between NRE and PRE with slope > 2, indicating that N was resorbed more rapidly than P. The scaling relationship of PRE-KRE showed considerable interspecific variation, with CJ exhibiting a negative slope (-0.492). NuREs were positively correlated with nutrient concentrations in summer green ABs but negatively correlated with those in AB litters. Within species, the three NuREs generally exhibited similar patterns of variation across geographic, climatic, and edaphic gradients, yet marked interspecific differences persisted. Soil and climatic conditions were identified as the primary environmental determinants of NuRE variability, although species-specific responses indicated that different nutrient elements were affected by distinct interactions among environmental factors. In summary, the three Calligonum species demonstrated differentiated nutrient resorption strategies, closely tied to both their internal nutrient status and environmental contexts. These findings provide valuable insights into nutrient use strategies and adaptive mechanisms in Calligonum and other assimilative-branch shrubs inhabiting arid ecosystems.

Dryland biodiversity-productivity relationships remain poorly resolved. Specifically, the environmental conditions governing the shift between complementarity and mass ratio mechanisms remain unclear, limiting the effectiveness of restoration and management strategies. To address this gap, the aim of this study was to investigate the geographical patterns of diversity and biomass production in herbaceous communities along a 2100-km precipitation gradient in North China. We studied how α- and β-diversity affect community-wide productivity using linear mixed-effects models and piecewise structural equation models, along with rolling-window change-point analyses. In arid regions, biomass productivity was primarily driven by interspecific niche complementarity, where higher functional diversity (FD(α)) enhanced resource-use efficiency. However, in semi-arid regions, productivity was regulated by the mass ratio effect, specifically through the traits of dominant species, including community weighted mean height and specific leaf area, as these species exploited broader resource spectra with increasing water availability. A critical mechanistic shift occurred at a mean annual precipitation (MAP) threshold of ∼168 mm (95% CI: 152-171 mm; p < 0.001). Below this threshold, productivity was driven by diversity-mediated complementarity and stress tolerant strategies. Conversely, as MAP surpassed 168 mm, the system transitioned to mass ratio control, coincident with a shift toward competitive strategies. Overall, our study provides empirical evidence to guide dryland management: prioritising the maintenance of functional diversity in arid communities, while emphasising dominant-trait optimisation (plant height and specific leaf area) in semi-arid communities to maximise aboveground biomass.

Against the backdrop of continuously increasing global nitrogen (N) deposition, the changes in photosynthetic carbon (C) allocation patterns of desert plants and their underlying mechanisms affecting soil C sequestration remain poorly understood. This study selected two representative species from desert ecosystems: the non-vascular moss Syntrichia caninervis and the vascular ephemeral plant Erodium oxyrhinchum as research subjects. Three N deposition levels were implemented: 0 (N0), 10.0 (N10), and 30.0 kg N ha−1 a−1 (N30), combined with 13C stable isotope labeling technique, to systematically investigate the effects of N deposition on plant photosynthetic C allocation and soil C sequestration. The experiment demonstrated that: (1) Aboveground 13C content in both species decreased significantly with increasing N input (P < 0.05); (2) N deposition significantly promoted photosynthetic C transfer to soil, with soil 13C allocation increasing from 0.8