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.

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.

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.

Biological soil crusts regulate dryland soil stability, hydrology, carbon cycling, nitrogen inputs, phosphorus availability, and microbial functioning, but their climate-change responses remain scattered across disciplines and reporting formats. We integrated Scopus-based bibliometric mapping with an audited quantitative meta-analysis to evaluate research trends, treatment effects, and evidence gaps in biocrust climate-change studies. The bibliometric dataset included 597 Scopus records indexed up to April 2026, and the quantitative synthesis analyzed log response-ratio treatment-control effects separately from model-coefficient evidence. Because response variables were biologically heterogeneous, we avoided a single global pooled effect and analyzed response domains separately. Bibliometric results showed rapid growth, with China, the USA, Spain, and Germany among the leading contributors. Dominant terms included climate change, soil crust, cyanobacteria, moss, lichen, CO₂, soil moisture, and microbial community, indicating growing emphasis on climate-change, microbial, and ecosystem-process research. Quantitatively, weighted evidence was concentrated in phosphorus-pool responses and precipitation-frequency physiology. Phosphorus pools increased under warming-related treatments, especially labile non-occluded phosphorus, whereas precipitation-frequency contrasts were associated with lower photoprotective pigments, photosynthetic physiology, and pigment/photosynthetic capacity. Nitrogenase activity and N₂-fixation-centered responses were more variable and uncertain. Integrated evidence-gap analysis revealed that microbial-community and carbon-cycling themes were highly visible bibliometrically but underrepresented by variance-supported effect sizes. Overall, biocrust climate-change research is conceptually broad but quantitatively uneven. Future studies should standardize reporting of treatment-control means, variances, sample sizes, treatment intensity and duration, biocrust type or surface-cover state, soil depth, site conditions, and raw data to improve predictive synthesis and support biocrust-based dryland sustainability indicators.

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.

Biological soil crusts (biocrusts) are photosynthetic soil-surface consortia that stabilize dryland soils, regulate hydrological fluxes, support nutrient cycling, and promote ecosystem recovery. However, inoculation often performs inconsistently because propagules must withstand desiccation, ultraviolet radiation, erosion, transport stress, and repeated wet–dry cycles before functional cover develops. This review evaluates encapsulated carrier-based bioformulation as a microbial delivery strategy for biocrust inoculants. It compares six platform families: dripping ionic gelation, reverse ionic gelation, spray drying, complex coacervation, emulsion or layer-by-layer systems, and capsule, pellet, or seed-ball approaches. Evidence is classified into three levels: direct biocrust delivery studies, close dryland restoration analogues, and transferable microbial encapsulation evidence from biocontrol, probiotic delivery, environmental biotechnology, and agricultural bioformulation. The synthesis supports platform matching rather than a universal carrier. Alginate beads provide the strongest direct support for mixed or fragile biocrust inocula because mild aqueous gelation can accommodate complex propagules and create hydrated microsites. Capsules and pellets offer advantages for handling, microsite placement, delayed release, and co-delivery with seeds or amendments. Spray drying appears more suitable for robust cyanobacterial or algal starter cultures than for intact mixed fragments, whereas reverse ionic gelation, coacervation, emulsion-derived systems, and multilayer coatings remain transferable design concepts. Representative direct studies report controlled-condition establishment within weeks and more than 70

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

Global warming has increased the frequency and severity of extreme climate events, resulting in the mortality of desert moss crusts. However, the pathways by which moss crust mortality affects rainfall partitioning and soil moisture dynamics remain poorly understood. We simulated moss crust mortality by applying heat shocks and established three treatments: bare sand, living moss crust, and dead moss crust. Using high-precision sensors, we continuously monitored soil moisture at depths of 0–3 cm, 3–6 cm, 6–9 cm, 9–12 cm, and 12–15 cm over a four-year period, aiming to quantify soil water content in the vertical soil profile and its dynamic response to rainfall events following moss crust mortality. Compared with living moss crusts, moss crust mortality significantly reduced soil water content in the upper 0–15 cm soil layer. Moreover, relative to bare sand, the dead crust treatment exhibited poorer hydrological performance, and this negative effect persisted for at least four years. Following rainfall events, moss crust mortality shifted soil moisture distribution toward shallower layers, shortened the response lag time, accelerated wetting front advancement, reduced water recharge to deeper soil layers, and increased the rate of water depletion. Rainfall amount and intensity were key factors regulating these soil moisture response characteristics. In particular, under the dead crust treatment, larger rainfall events resulted in greater losses of stored water. The mortality of moss crusts exerted a long-term negative impact on the availability of surface soil moisture in desert ecosystems, posing a significant threat to the establishment of plant communities and overall ecosystem functioning. This underscores the importance of protecting desert biocrusts and restoring their soil water regulation functions to improve water availability and ecosystem stability in degraded desert ecosystems.

In the context of global warming and increasing drought, clarifying intraspecific variation in plant xylem hydraulic traits and their ecological adaptation strategies is crucial for predicting vegetation stability and functional maintenance in arid ecosystems. This study investigated Reaumuria songarica, a widely distributed and highly drought-tolerant shrub native to the desert regions of northwestern China. By integrating quantitative anatomical analyses of xylem vessels and inter-vessel pits with trait network modelling, we systematically assessed the variation patterns and environmental responses of its hydraulic structural traits along an aridity gradient. The results demonstrated that: (i) R. songarica exhibits substantial intraspecific variation in hydraulic traits, with individuals in hyper-arid regions possessing larger pit aperture areas and higher pit densities, indicative of an 'opportunistic' water-use strategy that facilitates rapid responses to episodic rainfall events; (ii) different traits exhibited distinct responses to temperature, precipitation and soil conditions, with tissue-level traits being more responsive to temperature, while pit-level traits were primarily influenced by precipitation and soil factors; and (iii) vessels and pits displayed significant coordinated variation at the anatomical level. Trait network analysis further revealed that the topological structure of hydraulic traits was substantially reorganized along the aridity gradient, transitioning from a highly coordinated strategy centered on embolism resistance in arid regions to a structure-stabilization strategy centered on vessel wall thickness in hyper-arid regions. This study provides clear evidence of intraspecific variation in pit structure in R. songarica and uncovers the coordinated regulatory mechanism between pit and vessel structures. These findings offer microstructural insights into hydraulic adaptation strategies in desert plants and contribute theoretical support for drought-tolerant shrub selection and ecological restoration in arid regions.

Desert plants, despite overall well adapted to drought, exhibit considerable inter-specific differentiation of micro-habitats and variation in adaptive characteristics in the generally much water-limited yet spatially heterogeneous water regimes. Investigating the interplay between fine-scale spacial variation of environmental water regime and inter-specific differences in water-related physiology can provide an important basis for understanding the functional diversity and co-existence of desert plants. Here, we addressed this question by taking advantage of the remarkable niche differentiation of two dominant shrub species, Haloxylon ammodendron occupying the inter-dune lowlands and Haloxylon persicum colonizing the sand dunes in Gurbantunggut Desert of Northwest China. We precisely quantified the locations of each individual of the two congeneric species in transects established across the inter-dune lowland to dune crest landscape, measured soil water contents at different transect positions, and investigated water-related physiological traits of each individual. We found that the clear niche differentiation between the two sister species was paralleled by divergences in a suite of water-related functional traits. Particularly, such divergence indicates a clear trade-off between efficient water acquisition and drought tolerance. Higher hydraulic efficiency in H. persicum contributed to greater competitiveness in the sand dunes with relatively high soil water availability. In contrast, greater hydraulic safety and higher tissue water storage capacity in H. ammodendron contributed to its endurance in the more drought stressed inter-dune lowlands. Our findings indicate that variation of fine-scale soil moisture due to local factors like topography is a critical driver in shaping the species diversity in the heterogeneous environments of deserts.

Desiccation-tolerant mosses survive extreme water loss by activating efficient photoprotective mechanisms that prevent damage to the photosynthetic apparatus. The most resistant moss Syntrichia caninervis (S. caninervis) represents an important model for studying the molecular basis of dehydration resilience; however, the membrane and protein level processes, which enable rapid recovery of photosynthetic activity upon rehydration, remain insufficiently understood. In this work, we investigate the fluorescence (FL) dynamics of the photosynthetic apparatus of S. caninervis under three hydration states (hydrated, dehydrated and desiccated) in whole leaves using time-resolved FL spectroscopy. Time-resolved measurements with 10 ps resolution were performed to resolve excitation dynamics in both photosystems I (PSI) and II (PSII). The complex FL datasets were analysed using the spectral decomposition approach. Dehydrated and desiccated samples exhibit substantially reduced FL intensity compared to hydrated moss in steady-state experiments, indicating efficient quenching of chlorophyll excitation upon drying. The time-resolved FL measurements revealed that excitation transfer rates and the nature of quenched states strongly depend on hydration level in S. caninervis. In the hydrated state, FL dynamics are consistent with functional photosystems in plants. Upon dehydration, non-photochemical quenching is activated in both PSII and PSI, with PSII quenching persisting even at low temperatures. We therefore conclude, that S. caninervis employs few hydration-dependent photoprotective regimes, including distinct quenching mechanisms at both photosystems. Our results suggest the presence of ultrafast quenching processes under severe dehydration, which are progressively relieved during rehydration and replaced by alternative mechanisms supporting the recovery of photosynthetic activity.

ABSTRACT Arid regions are an important component of the global terrestrial carbon pool, yet how soil microorganisms regulate carbon metabolism in these systems remains insufficiently understood. Here, we combined a natural climatic gradient across arid northwestern China with standardized carbon addition incubations to examine the spatial patterns and controls of soil microbial carbon metabolic potential. Basal respiration, respiration after carbon addition, microbial biomass, extracellular enzyme activities, and soil nutrients were measured to assess how hydrothermal conditions, soil carbon availability, and microbial attributes jointly regulate microbial carbon responses. Our results showed that desert soil microorganisms were strongly constrained by carbon scarcity. Carbon addition greatly stimulated microbial respiration, whereas DNA content increased only slightly, indicating that microbial responses to carbon inputs were mainly driven by rapid metabolic activation rather than short‐term biomass growth. Across the climatic gradient, microbial respiration and carbon metabolic potential were not controlled by temperature or precipitation alone. Instead, their spatial patterns were closely associated with soil organic carbon and microbial biomass, suggesting that substrate supply and microbial pool size are key constraints on microbial carbon responses in desert soils. Structural equation modeling further showed that climate‐related effects were mainly mediated by organic carbon availability, microbial biomass, and carbon‐acquiring enzyme activities. Overall, our findings indicate that microbial carbon metabolism in drylands is jointly regulated by hydrothermal background, resource limitation, microbial biomass, and enzyme activity. Incorporating these resource‐mediated microbial processes into ecosystem models may improve predictions of soil carbon dynamics in arid and semi‐arid regions.

Microbial carbon use efficiency (CUE) is a central parameter for understanding soil carbon cycling and is widely used to predict soil organic carbon (SOC) stabilization and accumulation, microbial metabolic efficiency, and ecosystem carbon balance under global change. The isotope-based approaches currently employed to quantify CUE are grounded on a key assumption that assimilated carbon is predominantly allocated to growth and respiration. This assumption implicitly treats growth-related carbon investment as the dominant pathway linking microbial metabolism to SOC formation. However, in arid environments characterized by chronic water scarcity and nutrient impoverishment, microorganisms often allocate assimilated carbon to “non-growth carbon investments”, defined as carbon expenditures that do not directly generate new biomass but support survival, stress tolerance, and environmental persistence. These investments include maintenance respiration, dormancy, structural carbon allocation and extracellular polymeric substance production. This raises substantial uncertainty regarding whether the foundational assumptions of stable isotope probing-based CUE measurements can be directly applied to drylands. From both microbial ecological and methodological perspectives, this paper argues that isotope-based CUE measurements may systematically underestimate the true metabolic efficiency of microorganisms in drylands. We further examine the ecological mechanisms underlying this bias and outline future research directions. We propose that a “Adjusted CUE framework”—one that explicitly incorporates maintenance metabolism and survival-related carbon investments—should be developed for drylands. We also call for the broader adoption of integrative, multi-method approaches in global dryland carbon-cycle research to avoid misinterpreting microbial carbon allocation strategies and to improve the parameterization of SOC models under increasing aridity.

The impact of global climate change and human-induced nitrogen (N) deposition on winter weather patterns will have consequences for soil N cycling and greenhouse gas emissions in temperate deserts. Biological soil crusts (referred to as biocrusts) are crucial communities in soil and significant sources of nitrous oxide (N2O) emission in desert ecosystems and are sensitive to environmental changes. The contribution of bacteria and fungi to N2O production in drylands has been acknowledged. However, the effect of changes in snow cover and N deposition on the N2O production of different microbial groups of microorganisms is not yet clear. In this study, we examine the responses of fungi and bacteria mediated pathways involved in soil N2O production from biocrusts to longterm snow cover manipulation and N addition experiments in the Gurbantunggut Desert. These soils were incubated and subjected to biocide treatments (such as cycloheximide and streptomycin, and fungal and bacterial inhibitors), after which rates of potential nitrification and N2O production were measured. Compared with controls, snow removal treatments from bare sand, lichen crust and moss crust reduced background rates of N2O production by 29.41 %, 26.21 % and 20.49 %, respectively; N2O production rates were 1.53-fold higher in bare sand, 1.38-fold higher in lichen crust, and 1.56-fold higher in moss crust after N addition. The addition of streptomycin significantly reduced the potential nitrification rates of bare sand and biocrusts, indicating that bacteria may be important sources of NO3- production in biocrusts rather than fungi. Conversely, fungi were main sources of N2O production in biocrusts. Additionally, fungi also played a major role in N2O production in biocrusts after snow cover manipulation and N addition. Both snow cover manipulation and N addition treatment indirectly affected the N2O production in biocrusts by considerably affecting the content of substrate N and the abundance of microbial groups. Our research suggests that fungi are main contributors for denitrification in biocrusts, and that snow cover changes (removal snow and double snow) and N addition alter the contribution of biotic pathways responsible for N cycling.

Biological soil crusts (biocrusts) are essential for nitrogen (N) cycling in arid ecosystems, but how snow cover modulates these processes remains unclear. This study investigated the effects of variable snow cover on N fixation, ammonia oxidation (AO), and microbial networks across moss-, lichen-, and cyanobacteria-dominated biocrusts in China's Gurbantunggut Desert. Snow manipulations double snow (DS), ambient snow (CK), and removed snow (RS) were applied to biocrust plots in winter. Nitrogen fixation and AO rates, soil properties soil water content (SWC), organic carbon (SOC), inorganic N, and microbial co-occurrence networks were analyzed in spring. DS enhanced nitrogen fixation rates, particularly in cyanobacteria-dominated crusts (up to 0.4 μg N g-1 day-1), while moss crusts showed elevated fixation under RS conditions (rates can up to 0.4 μg N g-1 day-1), which correlated with increased SWC (r = 0.72) and SOC (r = 0.65). Conversely, RS reduced AO rates by 50-67 % across biocrusts, with cyanobacteria experiencing the steepest decline (20 μg N g-1 day-1). Microbial networks under DS exhibited higher modularity in moss crusts (modularity = 0.85), indicating structured, cooperative communities, while RS fragmented networks, especially in cyanobacteria (modularity = 0.41). Soil salinity (EC) and pH were negatively correlated with microbial activity under RS. Moss crusts showed resilience, maintaining stable N fixation and microbial diversity under varying snow cover, whereas cyanobacteria showed increased sensitivity to drought. These results highlight the critical role of snow cover in maintaining N cycling during the spring season via moisture retention and SOC accumulation. Declining snow cover, as predicted under climate change, may disproportionately affect cyanobacteria-dominated crusts and thus destabilize soil fertility. Conservation strategies that prioritize bryophyte biocrusts could enhance ecosystem resilience in arid landscapes. This study highlights the interplay between snow regimes, biocrust type, and microbial functionality, and provides insights for predicting N cycling dynamics in warming drylands.

Phyllosphere microorganisms play a vital role in enhancing the adaptability and functionality of their host plants. Although the effects of phyllosphere microbial communities on host functional traits and their association with host phylogeny has been widely investigated, it remains unclear whether host selection consistently drives the assembly of these communities. In this study, bacterial and fungal communities on the surfaces of 734 leaf samples were characterized using bacterial and fungal amplicon sequencing. These microbial communities were associated with 42 plant species native to the Gurbantunggut Desert, a representative temperate desert located in Central Asia. The research assessed the relative contributions of plant-related factors, abiotic environmental variables (such as climate and soil), and spatial components to the observed variation in phyllosphere microbial communities, and further inferred the topological structure of plant-microbe interaction networks. The results indicate that plant phylogeny, plant functional traits, abiotic environment conditions, and spatial factors account for variations in the bacterial community composition (36.4 %, 4.6 %, 1.0 %, and 0.1 %, respectively) and the fungal community composition (28.6 %, 3.0 %, 1.5 %, and 1.2 %, respectively), following a hierarchical trend of plant phylogeny > plant functional traits > abiotic environment > space. Plant phylogeny and functional traits play a central role in shaping the assembly of phyllosphere microbial communities, indicating that plant filtering effects significantly influence microbial composition. Analysis of plant-microbe interactions reveals distinct preferences of microbial taxa for plant hosts across different taxonomic levels and geographic regions. Bipartite network analysis further illustrates that plant-microbe networks are highly specialized and modular, with plant-fungal networks exhibiting greater host specificity compared to plant-bacterial networks. Collectively, these findings underscore plant filtering as the primary determinant of microbial community assembly in the desert phyllosphere and provide valuable insights into the macroecological patterns shaping plant-microbe interactions in arid ecosystems.

Syntrichia caninervis, a representative stress-tolerant moss, thrives under extreme conditions such as extreme temperatures, drought, and intense radiation, making it a top candidate for extraterrestrial colonization. However, whether the ecological adaptation traits of S. caninervis are consistent across different distribution areas and microhabitats and the interactive relationships among functional traits remain unclear. This study employed a plant trait network (PTN) approach to examine the relationships among 25 functional traits of S. caninervis within and outside shrub habitats to assess its ecological adaptability in temperate desert. Shrub microhabitats increased the biomass, leaf morphology, and photosynthetic efficiency of S. caninervis by improving the local hydrothermal environment while reducing the physiological stress response. The trait network of S. caninervis under shrub presented a relatively high edge density and average clustering coefficient and relatively low network diameter, average path length, and degree of modularity. These findings suggest that shrubs enhance trait network connectivity and functional collaboration of S. caninervis, effectively mitigating drought stress and optimizing resource utilization efficiency. Central trait analysis revealed that, under shrub conditions, Fv/Fm and soluble sugars were central traits, whereas exposed area, Fv/Fm and POD were central traits. As precipitation decreased and temperature increased, the leaf area and photosynthetic activity of S. caninervis initially tended to increase but then decreased. Simultaneously, its trait network connectivity strengthened, with both modularity and local tightness gradually increasing, reflecting its adaptation to drought and high-temperature stress through trait synergy and functional modular specialization. Structural equation modeling (SEM) analysis revealed that climate dominated the ecological adaptability of S. caninervis through both direct and indirect pathways, whereas shrubs significantly alleviated the negative impacts of drought stress by improving hydrothermal conditions. This study not only reveals the physiological adaptation strategies of moss species in extreme environments but also provides new insights into the adaptive mechanisms of moss species in desert ecosystems.

Moss crusts play a vital function in the phosphorus (P) cycle in arid regions. Global climate change and anthropogenic disturbances have led to differing levels of mortality in desert mosses. However, the effects of moss mortality on soil P fractions across different soil depths are still unclear. This study compared and analyzed the soil P fractions and P cycle-related enzyme activities across different soil depths between living and moss mortality crusts in the Gurbantunggut Desert. The results demonstrated that moss mortality have significantly increased the contents of resin-P and NaHCO-Pi (inorganic phosphorus) across all soil depths, and NaOH-Po contents in 5–20 cm soil. Conversely, the contents of NaHCO-Po and residual-P in 0–2 cm and 5–20 cm soil depths were decreased with the moss mortality. Compared with living moss crusts, moss mortality have enhanced the contents of available P (5