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Background: Network analyses are often applied to microbial communities using sequencing survey datasets. However, associations in such networks do not necessarily indicate actual biotic interactions, and even if they do, the nature of the interactions commonly remains unclear. While network analyses are valuable for generating hypotheses, the inferred hypotheses are rarely experimentally confirmed. Results: We employed cross-kingdom network analyses, applied trait-based functions to the microorganisms, and subsequently experimentally investigated the found putative predator–prey interactions to evaluate whether, and to what extent, correlations indicate actual predator–prey relationships. For this, we investigated algae and their protistan predators in biocrusts of three distinct polar regions, i.e., Svalbard, the Antarctic Peninsula, and Continental Antarctica. Network analyses using FlashWeave indicated that 89, 138, and 51 correlations occurred between predatory protists and algae, respectively. However, trait assignment revealed that only 4.7–9.3% of said correlations link predators to actually suitable prey. We further confirmed these results with HMSC modeling, which resulted in similar numbers of 7.5% and 4.8% linking predators to suitable prey for full co-occurrence and abundance models, respectively. The combination of network analyses and trait assignment increased confidence in the prediction of predator–prey interactions, as we show that 82% of all experimentally investigated correlations could be verified. Furthermore, we found that more vicious predators, i.e., predators with the highest growth rate in co-culture with their prey, exhibit higher stress and betweenness centrality — giving rise to the future possibility of determining important predators from their network statistics. Conclusions: Our results support the idea of using network analyses for inferring predator–prey interactions, but at the same time call for cautionary consideration of the results, by combining them with trait-based approaches to increase confidence in the prediction of biological interactions. FNXjBTWygxbKv-5R-GHg3p Video Abstract [ABSTRACT FROM AUTHOR]

Ecological restoration often requires exotic invasive plant control. In many ecosystems, reestablishment of biological soil crusts (biocrusts) is a desired restoration outcome because biocrusts enhance ecosystem function and may favor native plants over exotics. We sought to pair exotic plant suppression with biocrust restoration using a novel restoration material: biocrust‐covered weed barriers. We tested five different barriers, including three biodegradable weed barriers, one synthetic weed barrier commonly used in the study area, and burlap cloth, because it has previously been shown to be useful in biocrust establishment. We grew biocrust moss over the surface of each barrier type in a fog chamber. Each barrier type was attached to the ground in the field with moss on the underside of the barrier (moss‐down), the top, or not present. We monitored the establishment of moss biocrusts and exotic plants and the durability of the barriers. The most successful barrier type for biocrust establishment was burlap, but one biodegradable weed barrier made of maize‐derived polylactic acid (corn) promoted biocrusts, especially in the moss‐down position. Only the synthetic weed barrier suppressed exotic plants for two growing seasons. The corn barrier only partially suppressed exotic plants for one growing season. Less durable weed barriers were less able to suppress exotic plants. Though we failed to identify a biodegradable barrier that both stimulates biocrust recovery and suppresses exotic plants beyond one growing season, our results suggest that our goal may be attainable if more durable biodegradable weed barriers were used or created. [ABSTRACT FROM AUTHOR]

Biological soil crusts are important components of dryland ecosystems, showing variations in appearance, morphology, and function across developmental stages. However, the methods for recording biocrust developmental stages have not been simplified and standardized. In this study, three developmental grades for both cyanobacterial crust and moss crust were defined based on visual indicators such as color, thickness, and moss height. A field survey was conducted across three precipitation regions in northern China, during which the developmental grades of cyanobacterial and moss crusts were visually recorded. Key biocrust developmental indicators, including shear strength, penetration resistance, coverage, chlorophyll a content, and bulk density were measured for each grade. The results showed that both cyanobacterial and moss crusts could be effectively classified into three developmental grades based on these indicators, with a 90% concordance between the measured indicators and the defined grading method. This finding validated that the method could accurately reflect biocrust developmental stages while simplifying field recordings. Developmental indicators in various grades of cyanobacterial and moss crusts showed a moderate (30% < CV < 100%) to strong (CV > 100%) variation, highlighting the importance of environmental heterogeneity at the regional scale. Moreover, the grading method proved effective across varying spatial scales, highlighting its broad applicability. However, its validation across the comprehensiveness of target objects and the geographical scope remains limited. Future research should focus on expanding the grading method to include lichen crust, refining it across diverse ecosystems, and exploring the integration of advanced technologies such as hyperspectral imaging and machine learning to automate and improve the classification process. This study provides a simple and effective grading method for visually recording the developmental stages of biological soil crusts, which is useful for ecological research and field applications. [ABSTRACT FROM AUTHOR]

Some arguments on the durability, dynamism, applicability, cost, and environmental aspects of chemical and physical additives confirm the general tendency to apply biological amendments for soil and water resource conservation. In this regard, the application of biological soil crusts is regarded as one of the biological and environmentally oriented methods to improve the soil hydrological behavior, cohesion, aggregation, and erodibility in such a way as to withstand destructive agents for soil and water loss. Despite general agreement on the beneficial effects of microorganisms in reducing soil loss and runoff, no unique conclusion has been drawn to minutely report the extension and consequences of applying soil microorganisms in soil and water conservation. In the current endeavor, out of too many reports found following insight searches in the public domains, 77 journal papers published from 1990 to 2023 on the relationship between microorganisms on soil loss and runoff control were ultimately reviewed. Accordingly, the first successful research was reported in 2003. Our further inspections showed that more than 90 % of the investigations had been conducted in China, Spain, Iran, the United States, Palestine, and the west of the Jordan River. In 82 % of the internationally published investigations, the application of cyanobacteria for conserving soil and water resources has been either preferred or recommended. Overall, the outcome of our inspection showed that microorganisms have been effective in controlling runoff and soil loss, due to which a global increasing tendency to extend soil microorganisms-based approaches is seen for soil and water resources management. [ABSTRACT FROM AUTHOR]

The Fundão dam failure in Brazil stands as one of the most significant environmental disasters in global mining, causing extensive harm to soils and native vegetation. Despite ongoing restoration efforts, the potential of photosynthetic cryptogamic pioneer organisms, such as biocrusts, remains largely untapped. This study explores the inoculation of moss‐dominated biocrusts in mining tailings using a novel biodegradable glue technique. We began by assessing the diversity of mosses naturally occurring in these tailings, identifying six species. Among them, Hyophila involuta (Hook.) A. Jaeger emerged as the most suitable species for inoculation experiments. We compared the inoculation of biocrusts within the biodegradable glue bed to direct soil inoculation. Our findings revealed that 94.5% of the inoculated biocrusts adhered to the glue bed after 75 days, demonstrating the technique's global potential in overcoming challenges associated with moss inoculation. We emphasize the need for further research into the long‐term effects of biodegradable glue‐bed application on biocrust sustainability across different ecosystems, while also implementing habitat improvements to mitigate other environmental stress. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) promote plant growth by regulating soil nutrient dynamics and enhancing soil structure through the microorganisms they host. However, their impact on microbial nutrient limitation, a critical factor in nutrient cycling, remains underexplored. This study hypothesized that different types of biocrusts modulate soil nutrient limitations, influencing plant growth. A pot experiment was conducted to evaluate the effects of four treatments—control, diatom, Bacillus megatherium, and diatom–B. megatherium biocrusts—on soil structure, nutrient availability, microbial nutrient limitation, and ryegrass growth after 40 days of cultivation. The results indicated that the B. megatherium treatment exacerbated microbial C and N limitations and reduced available phosphorus (by 41.80%) and ryegrass biomass (by 29.19%) compared to the control. The diatom-B. megatherium treatment alleviated nutrient limitations but increased nutrient competition between soil microbes and plants, impairing plant performance. In contrast, the diatom treatment enhanced soil structure, alleviated microbial nutrient limitations, and significantly improved total capillary porosity (by 10%), available phosphorus (by 22.91%), saturated water content (by 21.81%), and ryegrass biomass (by 76.05%) while reducing soil bulk density (by 9.63%). These findings provide practical insights and a theoretical foundation for utilizing biocrusts to improve fluvo-aquic soil quality and promote sustainable plant growth. [ABSTRACT FROM AUTHOR]

Lichens are among the most distinctive and colorful organisms found in biological soil crusts (biocrusts). Along with cyanobacteria, green algae, and bryophytes, they inhabit the top few millimeters of the soil surface, forming the living skin of the soil. They cover large areas of the planet's arid and semiarid regions, as well as degraded terrestrial ecosystems in other regions. Although global studies of biocrusts have tripled in the last two decades, South America remains one of the least studied continents. In Argentina, ecological studies of biocrusts are increasing, but knowledge of the taxonomic diversity of the lichens that comprise them remains limited. Therefore, it is crucial to increase studies on terrestrial lichens, which, although often inconspicuous, may be more abundant than previously thought. To contribute to the knowledge of biocrust lichens taxonomy in Argentina, we proposed to 1) perform a bibliographic review of the works that reported species lists to confirm and update the taxonomic nomenclature and distribution, and 2) expand knowledge in less studied regions through the study of specimens from central Argentina. The results reveal that between 2002 and 2022, 78 crust-forming lichen species were recorded in Argentina. The richest family was Verrucariaceae, along with Collemataceae, Peltulaceae, and Lichinaceae distributed in the northern, western, and central- southern regions of the country, mainly in the arid and semiarid areas of Mendoza, San Juan, Neuquén, and San Luis. The most common lichen species found in the crusts were Placidium squamulosum, Endocarpon pusillum, Enchylium tenax, Peltula obscurans, and Psora decipiens, in descending order. We have expanded this lichen diversity with three new species records for Argentina: Gloeoheppia erosa, Heppia adglutinata, and Heteroplacidium divisum, as well as the distribution of Enchylium coccophorum, Peltula obscurans, Placidium squamulosum, and Psora icterica in the central region of the country. In this way, we hope that this study can serve as a starting point for future research on lichen composition in soil crusts. [ABSTRACT FROM AUTHOR]

Aims: Soil mosses play an important role in carbon sequestration. We aimed to provide accurate estimates of CO2 flux and identify the drivers in subtropical moss-dominated biocrusts at diurnal and seasonal scales in subtropical China. Methods: We used an automated, continuous carbon flux measurement system with transparent chambers to measure net ecosystem exchange of CO2 (NEE) of the miniature ecosystem of moss-dominated biocrusts from April 2017 to March 2018. Results: NEE during the study period ranged from -1.65 μmol m−2 s−1 to 1.77 μmol m−2 s−1, with a cumulative NEE of 95.14 g C m−2 y−1. On a daily basis, moss-dominated biocrusts acted as a carbon sink at daytime in the spring and winter but they acted as a carbon source at night-time throughout the year. Negative NEE (i.e., net carbon gain) was observed on 9% of the measurement days over the year, mostly when soil moisture was high. In the summer and autumn, moss-dominated biocrusts mostly acted as a carbon source throughout the entire day. Photosynthetically active radiation and soil moisture were the most important predictors of NEE variation. Daily NEE positively related to soil temperature, while soil moisture had a negative relationship with daytime NEE but not nighttime NEE. Conclusion: The strong temporal variation of NEE at the daily scale across different seasons emphasizes the importance of continuous flux measurements. This study also underscores the crucial role of soil moisture in affecting the carbon sink function of moss-dominated biocrusts in subtropical areas. [ABSTRACT FROM AUTHOR]

Biological soil crusts are integral to Arctic ecosystems, playing a crucial role in primary production, nitrogen fixation and nutrient cycling, as well as maintaining soil stability. However, the composition and complex relationships between the diverse organisms within these biocrusts are not well studied. This study investigates how the microbial community composition within Arctic biocrusts is influenced by environmental factors along an altitudinal gradient (101 m to 314 m). Metagenomic analyses were used to provide insights into the community composition, revealing that temperature, pH, and nutrient availability significantly shaped the community. In contrast, altitude did not directly influence the microbial composition significantly. Eukaryotic communities were dominated by Chloroplastida and fungi, while Proteobacteria and Actinobacteria prevailed among prokaryotes. Cyanobacteria, particularly orders such as Pseudoanabaenales, Pleurocapsales, and Nostocales, emerged as the most abundant photoautotrophic organisms. Our findings highlight the impact of environmental gradients on microbial diversity and the functional dynamics of biocrusts, emphasizing their critical role in Arctic tundra ecosystems. Arctic biocrusts are intricate micro-ecosystems, whose structure is strongly shaped by local physicochemical parameters, likely affecting essential ecological functions. [ABSTRACT FROM AUTHOR]

Biological soil crusts are complex biological soil layers formed by mosses, lichens, cyanobacteria, and the underlying soil, which together with plants affect rainfall infiltration, surface runoff, soil evaporation, and water movement in the soil. The soil desertification and soil erosion in the ecologically fragile areas of central Ningxia are serious problems, and the ecological environment is extremely fragile. Effective ecological restoration technologies are urgently needed. This study took the grassland in the ecologically fragile area of central Ningxia as the object and investigated the impact of three plant communities and symbiotic patterns of biological soil crusts on soil erosion through field simulated rainfall experiments. The results showed that: (1) At a rainfall intensity of 90 mm h−1, the initial runoff time of each slope was significantly positively correlated with plant community type and biological soil crust coverage, and prolonged with the increase of plant community type and biological soil crust coverage. (2) With the extension of rainfall duration, the cumulative runoff on each slope exhibited an increasing trend. (3) The sediment concentration in runoff on slopes under different plant community and biological soil crust symbiotic patterns was significantly different, with the sediment concentration decreasing as the type of plant community and the coverage of biological soil crusts increased. (4) With the increase in the diversity of plant communities and the coverage of biological crusts, there was a gradual reduction in the volume of accumulated sediment. This study offers scientific management strategies and practical guidance for soil and water conservation efforts in the ecologically vulnerable areas of central Ningxia, highlighting the importance of promoting these symbiotic models within the region. [ABSTRACT FROM AUTHOR]

[Objective] The purposes of this study are to reveal the effect of desert shrubs on soil nutrients under biocrusts, and to provide theoretical basis and scientific basis for the restoration and management of desert ecosystem in arid sandy area. [Methods] Soil samples were collected from 0—10 cm, 10—20 cm and 20—30 cm soil layers under non-shrubs biocrusts (control) and biocrusts of four typical shrubs ( Atriplex canescens, Caragana korshinskii, Caragana stenophylla and Artemisia ordosica) in Hongwei natural vegetation sand-fixing area in the southeastern margin of Tengger Desert. The contents of soil organic matter (SOM), water content (SWC), pH value, total nitrogen (TN), available nitrogen (AN), total phosphorus (TP), available phosphorus (AP), total potassium (TK) and available potassium (AK) were measured respectively. The effect of interaction between shrubs and biocrusts on soil quality in desert area were characterized by soil nutrient change. [Results] (1) Compared with the control plot, the interaction between shrubs and biocrusts affected soil nutrients, increased soil TN, TK, AK, AN, SOM, AP and cyanobacteria-lichen crust TP content, and reduced moss crust TP content. (2) Soil depth change, shrubs and biocrusts type had significant effects on soil nutrients, and the interaction between each two had no significant effect on TP. Except for AN and AP, the interaction between the three had significant effects on other nutrient indexes (p＜0.05) . (3) In the same soil layer, the contents of SOM, TN, TP and AK in the soil under the shrubs+moss crust were higher than those under the shrubs+cyanobacteria-lichen crust. (4) The soil nutrients under the four shrubs+biocrusts were enriched in the 0—10 cm soil layer, and the surface accumulation effect was obvious. The interaction between shrubs, biocrusts and soil depth had different enrichment ability for soil nutrients. [Conclusion] The interaction between shrubs and biocrusts can increase soil fertility, improve soil quality, and play an important role in maintaining a stable desert ecosystem. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) play pivotal ecological roles in regulating nitrogen cycling within desert ecosystems. While acknowledging the essential role played by ammonia-oxidizing microorganisms in nitrogen transformation, there remains a paucity of understanding concerning how disturbances to biocrusts impact the diversity and spatial distribution patterns among ammonia oxidizer communities within temperate deserts. This investigation delved into assessing how 4 years' worth of removing biocrust influenced niche differentiation between nitrifying archaea and bacteria while also examining its effects on shaping community structures of predominant ammonia-oxidizing archaea (AOA) within the Gurbantunggut Desert soils. Despite notable variations in abundance of ammonia-oxidizing microbes across distinct soil depths throughout different seasons, it became apparent that removing biocrust significantly altered both the abundance and niche pattern for AOA alongside their bacterial counterparts during winter and summer periods. Notably dominating over their bacterial counterparts within desert soils, AOA displayed their highest archaeal to bacterial amoA gene copy ratio (6549-fold higher) at a soil depth of 5–10 cm during summer. Moreover, substantial impacts were observed upon AOA diversity along with compositional changes following such perturbation events. The aftermath saw an emergence of more diffuse yet dynamic AOA communities, especially noticeable amidst winter when nitrogen and water limitations were relatively alleviated. In summary, our findings underscore how interactions between biocrust coverages alongside factors like soil temperature, total carbon content, or NO3−_N concentrations govern niches occupied by ammoxidation communities whilst influencing assemblage processes too. The sensitivity shown by dominant AOAs towards biocrust removal further underscores how biocrust coverage influences nitrogen transformation processes while potentially involving other communities and functions in desert ecosystems. [ABSTRACT FROM AUTHOR]

Serpentine soils are characterized by nutrient imbalances and high levels of potentially toxic metals (PTMs). These soils host depauperate plant communities of species with specialized adaptations. Initial studies showed that South African serpentine soils harbor distinct biocrust algal and cyanobacterial species compared to adjacent non‐serpentine soils, with these communities further differing based on high and low precipitation levels. Here, we investigated the bacterial and fungal diversity of biological soil crusts from serpentine and non‐serpentine soils at two precipitation levels. The bacterial and fungal communities were characterized using 16S rDNA and ITS metabarcoding, respectively. No significant differences could be found in bacterial richness and community structure. Nevertheless, bacterial taxa such as Archangium, Candidatus Solibacter, Chthoniobacter, and Microvirga were more abundant in serpentine biocrusts or biocrusts receiving lower precipitation. The fungal community structure was distinct between serpentine and non‐serpentine soils (p = 0.027) and between high and low precipitation (p = 0.018). Furthermore, fungal diversity was lowest in the drier, serpentine biocrusts compared to non‐serpentine (p = 0.001) and serpentine crusts receiving higher precipitation (p = 0.002). The fungal genera, Ramimonilia and Vishniacozyma, which are known to be resistant or tolerant to PTMs and other environmental extremes, were significantly more abundant (p = 0.036 and p = 0.016, respectively) in serpentine biocrusts, with the latter indicating serpentine habitats. This study concluded that soil type influenced the fungal alpha diversity, specifically in the serpentine soil, resulting in a decrease in fungal species richness. Furthermore, precipitation influenced fungal beta diversity by shaping distinct fungal communities found in the biocrusts of serpentine and non‐serpentine soils. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) play important ecological roles in many ecosystems, but their legacy effects in subtropical agricultural systems are poorly understood. This study investigated how biocrusts impact soil properties and subsequent crop rhizosphere microbiomes. Soil with (+BC) and without (−BC) biocrusts was cultivated and used to grow pepper plants in a greenhouse experiment. Soil physicochemical properties and microbial communities in the pre-planting soils, and microbial communities in crop rhizosphere were analyzed. The results showed that soils with biocrust had significantly higher organic matter, total nitrogen, alkaline hydrolyzable nitrogen, total phosphorus, and total potassium content. Microbial community structures differed significantly among treatments, with −BC soils exhibiting higher microbial diversity in pre-planting conditions, while +BC soils showed higher diversity in crop rhizosphere soils. Soil properties, especially extractable potassium, total nitrogen, and organic matter content, were significantly correlated with rhizosphere microbial community structure. Additionally, our results showed that the first principal coordinate (PCoA1) of soil microbial community structure was significantly correlated with rhizosphere microbiota. Multiple regression analysis revealed that pre-planting soil microbial diversity indices and certain soil physicochemical properties could predict crop rhizosphere soil microbial diversity. Our results demonstrate that biocrusts can enhance soil fertility and alter microbial communities in subtropical agricultural soils, with persistent effects on the crop rhizosphere microbiome. This study provides new insights into the ecological legacy of biocrusts in managed subtropical ecosystems and their potential agricultural implications. [ABSTRACT FROM AUTHOR]

Cyanobacterial extracellular polymeric substances (EPS) are secondary metabolites with high physiological importance for survival under ultraviolet radiation (UVR). This is particularly important in drylands, where cyanobacteria are the main components of biological soil crusts (biocrusts), which are subjected to strong natural solar UVB (280–315 nm) irradiation. This research aims to assess the capability of cyanobacteria isolated from biocrusts from Sejzi Plain, Iran, to produce EPS under UVB treatment. Using a top-down approach, two cyanobacterial species were isolated from biocrusts, and identified as Microcoleus vaginatus and Oscillatoria sp. Both taxa were exposed to controlled UVB radiation for 24, 48 and 72 h. Chlorophyll a content, more soluble EPS fraction (loosely bound EPS, LB-EPS), and less soluble EPS fraction (tightly bound EPS, TB EPS) production were measured. M. vaginatus and Oscillatoria sp. produced equal amounts of both EPS under the UVB treatment. A significant relationship was found for decreasing LB-EPS after 24 h of exposure to UVB, while the amount of TB EPS did not decrease, and even increased significantly after 48 and 72 h. The chlorophyll a content of treated cyanobacteria and their control culture was not significantly different. Therefore, under prolonged UVB up to 72 h, these cyanobacteria produced more TB-EPS than LB-EPS. Consequently, TB-EPS might contribute to higher survival under UVB than LB-EPS. [ABSTRACT FROM AUTHOR]

Biocrusts play an essential role in maintaining ecosystem stability, which is common in arid and semi‐arid areas. Although there have been some previous studies on the stoichiometry of biocrust subsoil in grazing systems, further research is needed to assess the effects of varying grazing intensities. Four grazing gradients were established to investigate the change mechanism of biocrust subsoil stoichiometry under grazing conditions, considering its seasonal response. These findings revealed that biocrusts' coverage and their chlorophyll content showed a parabolic trend of increasing and then decreasing with the increase in grazing intensity. At the same time, their standard response thresholds to grazing intensity ranged from 2.67 to 5.33 sheep/ha. Moreover, the premise that the biocrust is damaged by grazing trampling has become a consensus; our study found that the biocrust still played an important role, although its structure was destroyed because of its greenness (BG) increased. The influence of grazing intensity on the biocrust subsoil stoichiometry is unquestionable; in addition, they are influenced by a combination of vegetation (10% and 19%) and environmental influences (6% and 18%). Furthermore, it was observed that these changes did not compensate for the reproduction and development of biocrusts in grazing‐induced trampling damage. In this study, the integrated consideration of biocrusts into the grazing system fully affirmed its essential role. Additionally, it clarified the pathways and effect of grazing on biocrusts subsoil stoichiometry, providing a new perspective and reference for developing grazing strategy on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Inoculation of cyanobacteria has been studied as a valuable approach to promote soil stabilization and fertilization and counteract the erosion of marginal soils. One of the results of the inoculation of cyanobacteria is the formation of biological soil crusts, or biocrusts, which are complex soil communities playing a pivotal role in providing essential ecosystem services in drylands. While numerous studies have addressed the effects of different biocrust attributes on ecosystem functions, few studies have focused on the distribution of biocrust successional stages in the soil and their link with soil fertility properties. In this work, we investigated how the distribution of biocrust types (cyano-crust; cyano/moss crust, and moss crust) is related to soil nutrient status. We evaluated phototrophic abundance, exopolysaccharide production, and nutrient content in distinct biocrust types in an experimental area in the Hopq Desert, China, where their occurrence had been induced by cyanobacteria inoculation. In addition, we investigated the correlation between these variables. Photosynthetic pigment content, total carbohydrates, exopolysaccharides, organic C, and total N increased during the biocrust maturation stages. We found significant correlations between the levels of organic C, total carbohydrates, and total N with the abundance of diazotrophic cyanobacteria. Organic N was greater in the cyano/moss crust, while available P accumulated mainly in the cyano-crust. The three biocrust types are essential to each other as each represents a stage in which distinct nutrients are stored. This study complements previous studies by offering a more comprehensive view of how phototrophic variability in the distribution of biocrusts dominated by cyanobacteria or by mosses is closely interconnected with nutrient content and biocrust development. [ABSTRACT FROM AUTHOR]

[Objective] Soil saturated hydraulic conductivity (K,)reflects soil infiltration capacity and erosion resistance potential, which significantly affects hydrology and erosion processes. Economic fruit forest is an important land use type in the Three Gorges Reservoir area, biological crust wide-developed under the forest, which will inevitably drive the change in soil physical and chemical properties, thereby affecting K s, but the effect of biological crust development on soil saturated hydraulic conductivity and its driving mechanism in reservoir area is still unclear. Methods］ Therefore, in order to investigate the effect of biological crust development on K、in the Three Gorges Reservoir area. One site without biological crust (as control) and five moss crust sites with different coverage (()〜20%, 20% 〜4()%，40% 〜6()%，6()% 〜8()%，80% 〜1()()%) were selected under the economic fruit forest. The soil saturated hydraulic conductivity and basic soil physical and chemical properties of biological crust with different coverage gradients were determined by field sampling and laboratory analysis, combined with nonlinear regression, partial least squares regression and structural equation model methods. The changes in K、with biological crust coverage and main factors attributed to these changes were clarified. Results] (1) The development of biological crust significantly increased K s, and compared to control, of economic fruit forest covered by ()〜2()%, 2()%〜4()%, 4()%〜6()%, 6()%〜&)%，&)% 〜1()()% biological crust increased by 36.98%，33& ()9%，407.17%，900.66%，713.11%， respectively. (2) K、increased in an approximate logarithmic trend with the increase of biological crust coverage. When biological crust coverage was greater than 6()%: K、tended to be stable. (3) K、was significantly correlated with the biological crust characteristics and the differences in soil physical and chemical properties driven by biological crust. The thickness of biological crust, soil bulk density, total porosity, saturated water content and water-stable aggregate content were the main influencing factors leading to the differences in K、with different biological crust coverages. (4) The result of structural equation model showed that the development of biological crust was mainly through its indirect effect in improving soil structure (indirect path coefficient 1. 655 bigger than direct path coefficient (). 887) to increase K、. Conclusion] These results provide a theoretical basis for understanding the hydrologic and erosion processes of biological crust development in the Three Gorges Reservoir area, and also provide practical guidance for the prevention and controlling of soil and water loss in the economic fruit forest land. [ABSTRACT FROM AUTHOR]

[Objective] To determine the effect of biological soil crusts (biocrusts) on water evapotranspiration of the shrub-grass ecosystem. Methods］ The effect of biocrusts on water evapotranspiration of the shrubgrass ecosystem in water-wind erosion crisscross region of Loess Plateau was investigated by using original soil columns of field condition. Tn the study, the bare soil column was used as control, and three treatments were set up. The three treatments were shrub-grass (single plant shrub-2()% grass), shrub-grass-3()% biocrusts and shrub-grass-5()% biocrusts. Results］ The results showed that after 12 hours of simulated 3() mm precipitation infiltration, water content of 0--20 cm soil layer in the shrub-grass-biotic crust treatment was 15.4% higher than that in the bare soil treatment and 12.8% higher than that in the shrub-grass treatment. Compared with bare soil, soil water evapotranspiration of shrub-grass and shrub-grass with two level of biocrusts, coverage significantly increased. Among them, soil water evapotranspiration of shrubgrass treatment increased by 120.3% compared to bare soil, while shrub-grass-biocrusts increased by 116.5% on average. Biocrusts reduced soil water evapotranspiration of the shrub-grass ecosystem. Compared with the shrub-grass treatment, soil water evapotranspiration of the shrub-grass-biocrusts decreased by 1.7% on average. The degree of reduction of evapotranspiration was related to the coverage of biocrusts, period and soil depth. Among them, the water evapotranspiration of shrub-grass-5()% biocrusts was 13.4% lower than that of shrub-grass-3()% biocrusts. The reduction of water evapotranspiration of shrub-grass ecosystem caused by biocrusts was obvious during the first 1 〜4 days after rain. The reduction of water evapotranspiration of shrub-grass ecosystem caused by biocrusts mainly related to the evapotranspiration of 20一45 cm soil layer. Compared with the shrub-grass treatment, the water evapotranspiration loss of the ()-- 20 cm soil layer of the shrub-grass-biocrust treatment increased by 14. 4% on average, while the water dissipation below 20 cm decreased by 15.5% on average. Conclusion] Under the condition of 3() mm rainfall, biocrusts reduced the water evapotranspiration of shrub-grass ecosystem, which may beneficial the water deficit of shrub-grass vegetation in the wind-water erosion crisscross area. The study provides a reference for revealing the effect of biocrusts on water evapotranspiration in shrub-grass ecosystems. [ABSTRACT FROM AUTHOR]

In drylands, where water scarcity limits vascular plant growth, much of the primary production occurs at the soil surface. This is where complex macro‐ and microbial communities, in an intricate bond with soil particles, form biological soil crusts (biocrusts). Despite their critical role in regulating C and N cycling in dryland ecosystems, there is limited understanding of the fate of biologically fixed C and N from biocrusts into the mineral soil, or how climate change will affect C and N fluxes between the atmosphere, biocrusts, and subsurface soils. To address these gaps, we subjected biocrust–soil systems to experimental warming and drought under controlled laboratory conditions, monitored CO2 fluxes, and applied dual isotopic labeling pulses (13CO2 and 15N2). This allowed detailed quantification of elemental pathways into specific organic matter (OM) pools and microbial biomass via density fractionation and phospholipid fatty acid analyses. While biocrusts modulated CO2 fluxes regardless of the temperature regime, drought severely limited their photosynthetic C uptake to the extent that the systems no longer sustained net C uptake. Furthermore, the effect of biocrusts extended into the underlying 1 cm of mineral soil, where C and N accumulated as mineral‐associated OM (MAOM<63μm). This was strongly associated with increased relative dominance of fungi, suggesting that fungal hyphae facilitate the downward C and N translocation and subsequent MAOM formation. Most strikingly, however, these pathways were disrupted in systems exposed to warming, where no effects of biocrusts on the elemental composition of the underlying soil nor on MAOM were determined. This was further associated with reduced net biological N fixation under combined warming and drought, highlighting how changing climatic conditions diminish some of the most fundamental ecosystem functions of biocrusts, with detrimental repercussions for C and N cycling and the persistence of soil organic matter pools in dryland ecosystems. [ABSTRACT FROM AUTHOR]

A noticeable and significant biotic component of many terrestrial ecosystems around the world are soil surface communities, which are made up of cyanobacteria, mosses, liverworts, fungus, eukaryotic algae and lichens (also known as biological soil crusts or biocrusts). Biocrusts demonstrate the adaptability and tenacity of life in harsh environments as well as aperplexing resistance to the interplay of several environmental factors. Artificially induced biocrusts can thrive and significantly improve the soil environment through their biochemical activities. By secreting plant growth regulators and activating nitrogenase, cyanobacteria in biological soil crusts enhance the absorption of organic carbon and nitrogen, thereby increasing nutrient availability and maintaining soil fertility. Biocrusts are common, but they are threatened by global change-related causes, especially the interplay between intensifying land use and changing climate. The quantity of biocrust that is present locally, regionally and globally may be greatly decreased by these factors. As biocrusts are vital to the health of ecosystems and are in risk of vanishing, their influence on ecosystems and the consequences of their loss should be considered in studies and models of global change. [ABSTRACT FROM AUTHOR]

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Ecosystems of the fjell fields in the Khibiny Mountains (Kola Peninsula) are investigated, including vegetation, soils, soil algae, and invertebrate fauna. We use EUNIS habitat typification (2013) to differentiate habitats. The most common habitat types include (1) crustose–lichen (Rhizocarpon geographicum) rock on eluvium of base-rich, alkaline, and siliceous rocks (U5111); (2) lichen-, sedge-, and dwarf- and shrub–dominated turfs and cushions on gravelly and rocky slopes (U5112); (3) sedge-, moss-, and lichen–dominated on rubble and stony mountain plateaus and peaks (U5113); (4) biological soil crust on fine-earth and gravelly polygon edges (U5114); and (5) late snow bed moss vegetation (U5115). Soils of the fjell fields are represented by Leptosols. The content of soil organic C is very high (26–32%), despite the thin soil profile, which has no illuvial–eluvial differentiation by the content of SiO2 and R2O3. The total flora includes 176 species of plants and lichens. Soil alga flora is composed of 43 species, where green algae of Chlorophyceae prevails. Soil microarthropods are dominated by Collembola, Oribatida, and Mesostigmata, which are also typical for mountain tundra. The soil microbial activity and the diversity and abundance of soil algae and invertebrates depends on the habitat type and soil moisture, as well as on soil organic matter content and increases on wet substrates or under more complex vegetation. [ABSTRACT FROM AUTHOR]

Soil microbial inoculants are widely recognized as an environmentally friendly strategy for promoting crop growth and increasing productivity. However, research on utilizing the microbial resources from desert biological soil crusts to enhance crop growth remains relatively unexplored. In the present work, a bacterial strain designated AC1-8 with high levels of amylase, protease, and cellulase activity was isolated from cyanobacterial crusts of the Tengger Desert and identified as Bacillus cereus (CGMCC 1.60196). The refinement of the fermentation parameters of B. cereus CGMCC 1.60196 determined that the most effective medium for biomass production was composed of 5 g/L glucose, 22 g/L yeast extract and 15 g/L MgSO4, and the optimal culture conditions were pH 6.0, temperature 37°C, inoculation quantity 3% and agitation speed 240 rpm. Furthermore, the utilization of B. cereus CGMCC 1.60196 has resulted in substantial improvements in various growth parameters of maize seedlings, including shoot length, shoot fresh and dry weights, root fresh and dry weights, and the contents of chlorophyll a, chlorophyll b, and total chlorophyll. The most pronounced growth promotion was observed at an application concentration of 1 × 109 CFU/m2. These results suggest that the novel B. cereus strain, isolated from cyanobacterial crusts, can be regarded as an exemplary biological agent for soil improvement, capable of enhancing soil conditions, promoting crop cultivation and supporting food production. [ABSTRACT FROM AUTHOR]

Biocrusts are a critical surface cover in global drylands, but knowledge about their influences on surface soil thermal properties are still lacking because it is quite challenging to make accurate thermal property measurements for biocrust layers, which are only millimetres thick. In this study, we repacked biocrust layers (moss‐ and cyanobacteria‐dominated, respectively) that had the same material as the original intact biocrusts but was more homogeneous and thicker. The thermal conductivity (λ), heat capacity (C) and thermal diffusivity (k) of the repacked and intact biocrusts were measured by the heat pulse (HP) technique at different mass water contents (θm) and mass ratios (Wt), and the differences between repacked and intact biocrusts were analysed. Our results show that biocrusts substantially alter the thermal properties of the soil surface. The average λ of moss (0.37 W m−1 K−1) and cyanobacteria biocrusts (0.90 W m−1 K−1) were reduced by 63.0% and 10.3% compared with bare soil (1.00 W m−1 K−1), respectively. Edge effects including heat loss and water evaporation caused the λ and k of the biocrusts to be underestimated, but the C to be overestimated. The differences in thermal properties were significant (p <0.001), except for the differences in thermal conductivity between repacked and intact cyanobacteria biocrusts, which were not significant (p = 0.379). Specifically, in the volumetric water content (θv) range of 0 to 20%, the λ and k of the repacked moss biocrusts were underestimated by 59.1% and 61.8%, respectively, and the C was overestimated by 23.9% compared with the intact moss biocrusts. The λ and k of the repacked cyanobacteria biocrusts were underestimated by 15.8% and 79.2%, respectively, and the C was overestimated by 34.8% compared with the intact cyanobacteria biocrusts at the θv range of 0 to 30%. Typically, this difference increased as the θv rises between repacked and intact biocrusts. Our new measurements provide evidence that the thermal properties of biocrusts were previously misjudged due to the measurement limitations imposed by their limited thickness when measured in situ. Biocrusts are likely more significant in regulating soil heat and temperature in drylands than was previously assumed. [ABSTRACT FROM AUTHOR]

Vegetation restoration significantly increases overland flow resistance and decreases soil erosion. The cause of soil erosion is unknown, though grain resistance and form resistance are frequently confused with the overall overland flow resistance. The zonal specie of Bothriochloa ischcemum (Linn.). Keng (BI) and the dominant specie of Artemisia vestita Wall. ex Bess (AG) were selected to investigate the effect of vegetation near soil surface characteristics derived by vegetation restoration on overland flow resistance of grain resistance and form resistance. In total, 24 steel tanks were planted at six planting densities of 5, 10, 15, 20, 25, and 30 plants m−2, and two tanks were used as bare soil controls. Their hydraulic characteristics were tested under a constant rainfall intensity (60 mm h−1) on a 26.2% slope. The results showed that the grain resistance (fg) and form resistance (ff) ranged from 0.06 to 0.35 and 18.01 to 95.77 under six planting densities. Vegetation increased overland flow resistance by more than 90%, which was mainly attributed to ff. Vegetation near soil surface factors of the aboveground part, biological soil crusts, and root collar increased ff by 18.71 to 82.13, 0.74 to 11.50, and 1.61 to 3.40, respectively. Compared with BI, the mean value of fg in AG was 48.87% lower, whereas the mean value of ff was 1.36 times greater. The fg decreased with soil organic matter as a power function. The ff decreased with the Reynolds number, Froude number, and flow velocity and increased with vegetation coverage, aboveground biomass, and root collar area as power functions. Soil properties explained the majority of the variation in fg, and near the vegetation soil surface factors explained the majority of the variation in ff. Finally, ff was simulated using the Reynolds number, vegetation coverage, and root collar area. In addition, a simulation equation for the total flow resistance was established by distinguishing the grain resistance and the form resistance, and the performance of the model developed in this study was satisfactory (NSE = 0.97). [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) constitute a crucial biological component of the soil surface in arid and semi-arid ecosystems. Understanding the variations in soil microbial community assembly across biocrust successional stages is essential for a deeper comprehension of microbial biodiversity and desert ecosystem functioning. However, knowledge about the mechanisms of microbial community assembly and the factors influencing its development remains limited. In this study, we utilized amplicons sequencing to assess the compositions of bacterial and fungal communities in bare sand and three types of biocrusts (light cyanobacterial biocrusts, dark cyanobacterial biocrusts, and moss crusts). Subsequently, we analyzed the ecological processes shaping microbial community composition and structure, along with the influencing factors. Our results revealed a significant increase in bacterial diversity and no significant changes in fungal diversity during biocrust development. The relative abundances of the copiotrophic bacteria (e.g., Actinobacteria, Acidobacteria, and Bacteroidetes) showed significant increases, while oligotrophic bacteria (e.g., Proteobacteria and Firmicutes) decreased over time. Moreover, the relative abundances of Ascomycota, which exhibit strong resistance to adverse environmental conditions, significantly decreased, whereas Basidiomycota, known for their ability to degrade lignin, significantly increased throughout biocrust development. Additionally, stochastic processes (dispersal limitation and drift) predominantly drove the assemblies of both bacterial and fungal communities. However, the relative importance of deterministic processes (homogeneous selection) in bacterial assembly increased during biocrust development. Structural equation modeling indicated that bacterial community assembly was primarily related to soil water content, whereas fungal community assembly was primarily related to total organic carbon. These findings provide a scientific foundation for investigating the formation and development of biocrusts, and further insights into the conservation and sustainable management of biocrust resources under future climate change scenarios. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) are crucial elements of desert ecosystems, exhibiting patchy distribution patterns across the soil surface and significantly impacting surface soil nutrient dynamics. However, the influence of biocrust patch units, serving as fundamental functional entities, on microbial nutrient restriction remains underexplored. This study conducted measurements on moss crust patches of varying sizes and subcrust soils. Stoichiometric analysis of extracellular enzyme activities (EEAs) related to carbon, nitrogen, and phosphorus was performed, along with vector and redundancy analyses to evaluate microbial nutrient limitation and key influencing factors. The findings reveal that both patch size and soil layer of biocrusts collectively influence soil nutrients and enzyme dynamics, with heightened enzyme activity observed in the crust layer. Vector analysis based on EEA stoichiometry indicates that moss crust patch size insignificantly impacts microbial nutrient restriction within the crust layer. However, microbial nitrogen restriction in the subcrust layer demonstrates a “single-peak” trend, initially increasing before gradually declining. This suggests that microorganisms in medium-sized crust patches exhibit peak activity, intensifying nutrient competition. This research underscores the pivotal role of biocrust patch units as fundamental functional entities, offering comprehensive insights into microbial metabolic constraints under crust cover. The findings underscore the significant implications of enzyme stoichiometric characteristics for desert land management and conservation. [ABSTRACT FROM AUTHOR]

This document is a recent literature review on lichens, specifically focusing on various research articles and publications related to lichens. The articles cover a range of topics, including new species discoveries, the effects of environmental factors on lichen communities, and taxonomic revisions. The document provides a comprehensive list of the articles, their authors, and the journals they were published in. It serves as a valuable resource for library patrons conducting research on lichens. [Extracted from the article]

Biological soil crusts (BSCs) serve important functions in conserving biodiversity and ecological service in arid and semi-arid regions. Afforestation on shifting sand dunes can induce the formation of BSC on topsoil, which can accelerate the restoration of a degraded ecosystem. However, the studies on microbial community succession along BSC development under sand-fixation plantations in desertification areas are limited. This paper investigated the soil properties, enzymatic activities, and bacterial and fungal community structures across an age sequence (0-, 10-, 22-, and 37-year-old) of BSCs under Caragana microphylla sand-fixation plantations in Horqin Sandy Land, Northeast China. The dynamics in the diversities and structures of soil bacterial and fungal communities were detected via the high-throughput sequencing of the 16S and ITS rRNA genes, respectively. The soil nutrients and enzymatic activities all linearly increased with the development of BSC; furthermore, soil enzymatic activity was more sensitive to BSC development than soil nutrients. The diversities of the bacterial and fungal communities gradually increased along BSC development. There was a significant difference in the structure of the bacterial/fungal communities of the moving sand dune and BSC sites, and similar microbial compositions among different BSC sites were found. The successions of microbial communities in the BSC were characterized as a sequential process consisting of an initial phase of the faster recoveries of dominant taxa, a subsequent slower development phase, and a final stable phase. The quantitative response to BSC development varied with the dominant taxa. The secondary successions of the microbial communities of the BSC were affected by soil factors, and soil moisture, available nutrients, nitrate reductase, and polyphenol oxidase were the main influencing factors. [ABSTRACT FROM AUTHOR]

The role of runoff in providing nutrients to runon loci in deserts was not extensively explored. Here we report 2 years of measurements of the chemical composition of rain and runoff (three events for each year, which correspond to the long‐term runoff events) in plots that were constructed over four biocrust types in the Negev Desert, Israel. The enrichment ratios showed high variability, being high for K+ (3.7), moderately high for NH4+ (1.6) and slightly high for Mg2+ and SO42− (1.2). It was low for Cl− and NO3− (0.5), moderately lower for Ca2+ (0.7) and slightly lower for Na+ and HCO3− (0.8). When examined per rain event, significant higher concentrations were found for K+ and Mg2+ while NO3− exhibited significantly lower concentration. The high enrichment of K+ and the enrichment of Mg2+ may point to a biogenic origin. While K+ enrichment is suggested to result from K+ excretion by the cyanobacteria, bacteria, and possibly by the mosses following cell wetting and the K+ role in cell osmoregulation, decomposition and erosion of the chlorophyll pigment may result in Mg2+ release. On the other hand, the data point out that despite the crust capability to fix nitrogen and thus to provide its own needs for nitrogen, NO3− was depleted from the runoff water, a phenomena that may be explained by the crust preference to utilise available low‐cost nitrogen provided by rain. Due to runoff accumulation at small depressions within the interdune and at the dune‐interdune interface, runoff may contribute additional amount of nutrients to these habitats. For the dune‐interdune interface it may account for an addition of 273.8% and 35.3% of the total potassium and nitrogen, respectively. The addition of water and nutrients may have important contribution to the growth of the moss‐dominated biocrusts and the shrubs at the dune‐interdune interface, being responsible for the formation of 'mantles and islands of fertility' at the dune‐interdune interface. It also points to the possible role that biocrusts may play in agroforestry practices. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biocrusts represent associations of lichens, green algae, cyanobacteria, fungi and other microorganisms, colonizing soils in varying proportions of principally arid biomes. The so-called grit crust represents a recently discovered type of biocrust situated in the Coastal Range of the Atacama Desert (Chile) made of microorganisms growing on and in granitoid pebbles, resulting in a checkerboard pattern visible to the naked eye on the landscape scale. This specific microbiome fulfills a broad range of ecosystem services, all probably driven by fog and dew-induced photosynthetic activity of mainly micro-lichens. To understand its biodiversity and impact, we applied a polyphasic approach on the phototrophic microbiome of this biocrust, combining isolation and characterization of the lichen photobionts, multi-gene phylogeny of the photobionts and mycobionts based on a direct sequencing and microphotography approach, metabarcoding and determination of chlorophylla+b contents. Metabarcoding showed that yet undescribed lichens within the Caliciaceae dominated the biocrust together with Trebouxia as the most abundant eukaryote in all plots. Together with high mean chlorophylla+b contents exceeding 410 mg m−2, this distinguished the symbiotic algae Trebouxia as the main driver of the grit crust ecosystem. The trebouxioid photobionts could be assigned to the I (T. impressa/gelatinosa) and A (T. arboricola) clades and represented several lineages containing five potential species candidates, which were identified based on the unique phylogenetic position, morphological features, and developmental cycles of the corresponding isolates. These results designate the grit crust as the only known coherent soil layer with significant landscape covering impact of at least 440 km2, predominantly ruled by a single symbiotic algal genus. [ABSTRACT FROM AUTHOR]

This article is an editorial that discusses the development and ecological functions of biological soil crusts (biocrusts). Biocrusts are composed of microorganisms and play important roles in soil stabilization, microbial diversity, and ecosystem development. The editorial emphasizes the need for further research on biocrust communities and their impact on landscape-scale outcomes. It also highlights the ecological functions of biocrusts, such as reducing erosion and influencing biogeochemical cycles. The article concludes by discussing the importance of understanding biocrusts for ecological restoration and land management strategies. Another document provides a list of references for articles related to biological soil crusts, covering topics such as land degradation neutrality, ecological restoration, and the impact of biocrusts on microbial communities. The articles also explore the composition and response of biocrusts to climate change and physical disturbance, as well as their effects on soil properties and metabolic response to hydration. [Extracted from the article]

A significant fraction of Earth's ecosystems undergoes periodic wet‐dry alternating transitional states. These globally distributed water‐driven transitional ecosystems, such as intermittent rivers and coastal shorelines, have traditionally been studied as two distinct entities, whereas they constitute a single, interconnected meta‐ecosystem. This has resulted in a poor conceptual and empirical understanding of water‐driven transitional ecosystems. Here, we develop a conceptual framework that places the temporal availability of water as the core driver of biodiversity and functional patterns of transitional ecosystems at the global scale. Biological covers (e.g., aquatic biofilms and biocrusts) serve as an excellent model system thriving in both aquatic and terrestrial states, where their succession underscores the intricate interplay between these two states. The duration, frequency, and rate of change of wet‐dry cycles impose distinct plausible scenarios where different types of biological covers can occur depending on their desiccation/hydration resistance traits. This implies that the distinct eco‐evolutionary potential of biological covers, represented by their trait profiles, would support different functions while maintaining similar multifunctionality levels. By embracing multiple alternating transitional states as interconnected entities, our approach can help to better understand and manage global change impacts on biodiversity and multifunctionality in water‐driven transitional ecosystems, while providing new avenues for interdisciplinary studies. [ABSTRACT FROM AUTHOR]

Studies performed in North America, Africa, and South America have led to the isolation of four new species of Kastovskya, a filamentous cyanobacterial genus that before this manuscript had only one species, Kastovskya adunca from Chile. Kastovskya nitens and K. viridissima were isolated from soils on San Nicolas Island, K. sahariensis was isolated from hypolithic habitats from the Sahara Desert in Algeria, and K. circularithylacoides was isolated from hypolithic habitats in Chile. The molecular analyses are corroborated by morphological data, morphometric analysis, and ecological and biogeographical considerations for robust polyphasic descriptions of all taxa. The peculiar transatlantic distribution of this genus bears similarity to other taxa in recently published studies and is in agreement with a hypothesis suggesting that cyanobacteria in Africa may disperse to the Americas on dust particles during windstorms. This work is unusual in that species in a single rare cyanobacterial genus with a disjunct distribution are described simultaneously from three continents. The 16S rRNA gene analyses performed for this study also revealed that another recent genus, Arizonema, is clearly a later synonym of Symplocastrum. This issue is resolved here with the collapsing of the type species Arizonema commune into Symplocastrum flechtnerae. [ABSTRACT FROM AUTHOR]

[Objective Wind-water erosion crisscross region in Loess Plateau is a typical fragile ecosystem. Biological soil crusts (BSCs) are widely distributed in this region and play key roles in the accumulation and transformation of soil organic carbon (SOC). However, the effect of BSCs succession and microorganisms on enzymes related to organic carbon conversion is still unclear. [Methods] In this manuscript, SOC contents. microbial number and enzymes related with carbon conversion in different BSCs types were investigated. The relationships among SOC, microbial number and enzume activities related with carbon conversion were also analyzed by SEM model. [Results] (1) BSCs succession significantly inceased SOC content and enzyme activities related with carbon conversion. SOC and enzyme activities in BSCs layer (0-2 cm) were significantly higher than those in bare sand 2-5 cm soil layer (p<0.05). (2) The number of bacteria, fungi and actinomyces in moss crusts was the highest, and the number of fungi and actinomyces significantly increases with BSCs succession. Bacteria and fungi in the BSCs were significantly higher than those in 2-5 cm soil layer. However, actinomycetes in BSCs (except moss crusts) were lower than 2-5 cm layer. (3) SEM model indicated that SOC, enzyme activities and microbial number showed significant correlation. [Conclusion] The accumulation of SOC by BSCs succession provided a rich substrate and nutrients for enzymes related with carbon conversion and microbes, which were helpful for the increase of microbes and improvement of enzyme activities related with carbon conversion. Microbes play critical roles in driving enzyme activities related with carbon conversion and maintaining carbon balance in BSCs. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) can thrive under environmental conditions that are stressful for vascular plants such as high temperatures and/or extremely low moisture availability. In these settings, and in the absence of disturbance, cover of biocrusts commonly exceeds cover of vascular plants. Arid landscapes are also typically slow to recover from disturbance and prone to altered vegetation and invasion by exotic species. In the sagebrush ecosystems, cover of annual, exotic, invasive grasses are lower where cover of biocrusts and vascular plants are greater, suggesting that biocrusts play a role in helping arid sites avoid conversion to dominance by invasive grasses. The conceptual framework for assessing ecological resistance and resilience (R&R) is used across the region to estimate the risk of invasion by annual grasses and the likelihood of recovery of native plants following disturbance. However, this framework does not currently account for biocrusts. We used data collected by the Bureau of Land Management Assessment, Inventory, and Monitoring program to relate biocrusts, specifically the presence of lichens and mosses, to the R&R framework. Lichens frequently occur on warm, dry sites, classified as lower R&R. Mosses frequently occur on sites classified as moderate or moderately low R&R. Without management practices that favor biocrusts in low‐moderate R&R, these areas may be more vulnerable to transitioning from being dominated by shrubs to annual grasses. Under climate change scenarios, the area occupied by lower R&R sites is likely to increase, suggesting that the role of biocrusts in maintaining site resistance to invasion may also increase. [ABSTRACT FROM AUTHOR]

Various factors influence biocrust effects on infiltration and soil moisture. On China's Loess Plateau, well‐developed moss‐dominated biocrusts reduce infiltration and suppress shrub growth, however, the interrelationships between rainfall conditions and disturbance management to alleviate these impacts are unknown. In a semiarid watershed on the Loess Plateau, we applied two forms of disturbance, scarification (controlled harrowing) and compaction (simulated grazing), at four intensity levels (control‐intact, light, moderate, and heavy) to well‐developed moss‐dominated biocrusts and a bare soil (BS) for comparisons to form eight treatments with three replications. Rainfall intensity and depth, soil moisture, run‐off, and sediment yield were measured during the rainy season (July–October). In total, well‐developed biocrusts did not significantly affect infiltration but reduced soil moisture at depths of 120–180 cm (p < 0.05), and disturbance increased infiltration and deep soil moisture beneath biocrusts (p < 0.05). Rainfall conditions changed the effects of biocrusts and disturbance. Under long, low‐intensity rainfall, moss‐dominated biocrust infiltration was slightly greater than BS, but scarification increased infiltration and compaction reduced it (p < 0.001). Under short, high‐intensity rainfall, biocrusts reduced infiltration, and disturbance intensity increased infiltration and sediment yields (p < 0.001). Light grazing or using light or moderate scarification improves well‐developed moss‐dominated biocrust infiltration in the pastures during May–June before the rainy season during July–October on the Loess Plateau, while avoiding increased soil erosion. [ABSTRACT FROM AUTHOR]

Restoring biological crust (biocrust) in disturbed drylands is challenging due to the difficult environmental conditions, such as limited soil moisture, low soil nutrients, and extreme temperatures, that impede growth. Understanding how the key components of biocrust—mosses, lichens, and cyanobacteria—react to different environmental factors informs the optimal timing, locations, and species composition for biocrust reintroduction, thereby increasing the likelihood of establishment. Here, we inoculated soils with a diverse range of biocrust organisms, analogous to seeding an area with diverse vascular plant seeds, and varied environmental conditions to observe how these changes influenced the development and functions of reintroduced biocrust. We found that by manipulating soil texture and time spent wet, we can change the proportional cover of biocrust within a restoration‐like setting. Specifically, we found that 4 months after inoculation, finer textured soils that received more water become dominated by moss cover, while coarser textured soils with less water remained dominated by cyanobacteria cover, and the interactions between texture and time spent wet strongly influenced cover. We found biocrust morphological group cover had a small, but detectable, effect on ecosystem functions (soil stability and nitrogenase activity, a proxy for nitrogen fixation), but that environmental conditions had a stronger impact on the functions we measured. Manipulative experiments in controlled environments, like this one, can help elucidate the mechanisms underlying the establishment rate and patterns of biocrusts post‐inoculation, and inform implementation of inoculations in the field. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) are widespread soil photosynthetic communities covering about 12% of Earth's land surface, and play crucial roles in terrestrial carbon (C) and nitrogen (N) cycles, yet scalable quantifications of biocrusts and their biogeochemical contributions are notably lacking. While remote sensing has enormous potential to assess, scale, and contextualize biocrusts and their functions, the applicability of hyperspectral data in predicting C‐ and N‐related biocrust traits remains largely unexplored. We address this issue by evaluating the potential of in situ hyperspectral data to predict C and N across a range of biocrust species and different environmental conditions. We found that in situ hyperspectral reflectance measurements can be used to predict biocrust tissue C/N ratios and N concentrations with relatively high accuracy but to a lesser extent for potential biocrust N2 fixation rates. Critical wavelength domains included the visible region of the spectrum from roughly 490–600 nm, which most effectively captured variations in biocrust tissue C, and the shortwave infrared region from 1,150 to 1,350 nm and 1,550–1,650 nm, which most effectively captured biocrust tissue N and N2 fixation potential. Finally, we provide evidence that multi‐ and hyperspectral missions with targeted band placement, such as the proposed 26‐band Landsat Next, could be effective in predicting biocrust traits. This work provides a critical step in understanding how to apply data from new and upcoming satellite missions to the monitoring of biocrusts. Plain Language Summary: Biological soil crusts (biocrusts) are communities of organisms such as cyanobacteria, fungi, and lichens existing on soil surfaces. Biocrusts play an important role in the carbon (C) and nitrogen (N) cycles of terrestrial ecosystems. The C and N status of biocrusts can be examined in various ways. However, the applicability of studying C and N status of biocrusts using spectral reflectance is poorly explored. We combined statistical models and spectral reflectance measured using a spectroradiometer within the wavelength range from 400 to 2,450 nm to predict variations in C and N status of samples from 14 representative biocrust species, and under both wet and dry conditions. We found that variations in biocrust tissue C/N ratios and N concentrations could be accurately predicted. We also found that the wavelength range of 490–600 nm, and 1,150–1,350 nm as well as around 1,600 nm are the most important wavelength domains to study C and N status of biocrusts. Finally, we provide evidence that upcoming satellite missions with proper band placement, such as the proposed 26‐band Landsat Next, could be effective in predicting biocrust traits. Results from this work shed light on applying data from upcoming satellite missions to the monitoring of biocrusts. Key Points: The applicability of hyperspectral data in predicting carbon‐ and nitrogen‐related biocrust functional traits is poorly understoodVisible and shortwave infrared region of the spectrum best predicted variations in carbon‐ and nitrogen‐related biocrust functional traitsMulti‐ and hyperspectral satellite missions with targeted band placement could be effective in predicting biocrust functional traits [ABSTRACT FROM AUTHOR]

The study explores the aftermath of a wastewater reservoir failure in a phosphate fertilizer industry, resulting in the release of acidic water containing phosphorus and sulfate compounds into the Ashalim stream's Nature Reserve in the Judean desert, which affected the soil surface biological crusts (biocrusts) layer. The study aims to examine contamination effects on biocrusts over 3 years at two research sites along the stream, compare effects between contaminated sites, assess rehabilitation treatments, and examine their impact on soil characteristics. Hypotheses suggest significant damage to biocrusts due to acidic water flow, requiring human intervention for accelerated restoration. The results indicate adverse effects on biocrust properties, risking its key role in the desert ecosystem. The biocrust layer covering the stream's ground surface suffered significant physical, chemical, and biological damage due to exposure to industrial process effluents. However, soil enrichment treatments, including biocrust components and organic material, show promising effects on biocrust recovery. [ABSTRACT FROM AUTHOR]

Due to the scarcity of biological resources, desert areas are unable to achieve long-term carbon sequestration. Biological crust is a pioneer organism in desert areas and plays an important role in long-term carbon sequestration. However, the development of natural biological crust is slow. Clay plays an important role in the formation and development of biological crusts, and has a strong protective effect on soil organic carbon. Therefore, this paper explores the impact and mechanism of adding kaolin on the organic carbon of soil biological crust system, aiming to provide new solutions for the long-term carbon sink in desert areas. Through testing particle size, specific surface area and pore volume, chlorophyll a, chlorophyll fluorescence, microbial community, and soil organic carbon (SOC), it has been found that the addition of kaolin changed the physicochemical properties and microbial community structure of the system, promoted the growth of biochar, and strengthened the protective effect of the system on SOC. After 112 days of cultivation, the results show that the accumulation of SOC in the kaolin-based biological crust system increases to 145% of the algae inoculation group. [ABSTRACT FROM AUTHOR]

An analysis of the ecological characteristics of cyanobacteria of the Svalbard Archipelago was carried out. Two groups of habitats (aquatic and terrestrial ones) were identified. The degree of water saturation was the main factor determining the development of cyanobacteria. The variability of habitats can be represented as a gradient of moisture from typically aquatic to subaerophytic and dry terrestrial habitats. Based on the number of finds and species richness, the most favorable habitats for cyanobacteria in Svalbard were as follows: (1) rocky communities under conditions of sufficient moisture, (2) exposed soil surfaces on which biological soil crusts were formed, (3) well-warmed slow streams, and (4) specific waterlogged habitats, such as seepages. Using the example of the analysis of the ecological characteristics of species growing on the archipelago, the concept of eurybiont properties of cyanobacteria was shown to be inconsistent. The greatest plasticity was exhibited by Nostoc commune Vauch. ex Born. et Flah., Microcoleus autumnalis (Trev. ex Gom.) Strunecky et al.,Calothrix parietina Thur. ex Born. et Flah., Oscillatoria tenuis C. Ag. ex Gom., and Pseudanabaena frigida (Fritsch) Anagn. All species, including those mentioned above, had obvious ecological preferences. An analysis of the substrate specificity of cyanprokaryotes indicated that the greatest number of their species was found in soil, rocky substrates, and moss-like environments. [ABSTRACT FROM AUTHOR]

Using microorganisms as biocontrol agents against soilborne plant pathogens is a promising alternative to chemical pesticides. However, only some biocontrol agents have proven effective under field conditions. This study explores the potential of highly resilient microalgae isolated from harsh environments, such as Biological Soil Crusts and agricultural fields in semi-arid regions, as a novel and sustainable approach to biocontrol. Fifty-nine microalgal strains, including thirteen cyanobacteria and forty-six green algae, were isolated and identified. Dual-culture plate assays and toxicity tests of microalgal growth media were conducted to evaluate the antifungal activity of the isolates against eight representative soilborne pathogens. The results showed that many microalgae strains exhibited significant inhibitory effects on the growth of specific fungal pathogens, although the activity varied among different microalgal strains and pathogen species. Some strains even promoted the growth of certain fungi. The lack of a clear pattern in the antifungal activity highlights the complexity and specificity of the interactions between microalgae and soilborne pathogens. An "Inhibition Effectiveness" metric was developed to quantify biocontrol potential based on fungal growth inhibition. The green algal genus Desmodesmus, particularly Desmodesmus subspicatus isolates, showed higher antifungal efficacy than other genera. While the inhibitory mechanisms remain unclear, the results demonstrate the promising biocontrol capabilities of microalgae from extreme environments like BSCs. Further research could unlock novel opportunities for sustainable disease management by harnessing specific microalgal strains or synergistic strain combinations targeting soilborne pathogens. [ABSTRACT FROM AUTHOR]

Globally, biological soil crusts (BSCs) are crucial ecosystem components that perform essential functions important to ecosystem stability. However, the potential mechanisms of BSC's effect on vascular plant recruitment and establishment are largely unknown. Furthermore, few studies have considered BSC‐vascular plant analyses in conjunction with BSC microenvironments, seed traits, and plant life stages simultaneously. Thus, we chose six typical plants with different seed traits on the Loess Plateau and conducted a growth chamber experiment to evaluate the effects of BSC types, disturbance, seeding positions, and moisture on seed germination, survival, and seedling growth. We also explored the effects of BSC presence and disturbance on seedling emergence through field investigation. The results indicated that the main effects of the four factors, BSC type, disturbance, seeding location, and moisture, and their two‐ and three‐dimensional interactions had significant effects on the performance of most of the studied species. Disturbance and wetting treatments with shorter watering intervals promoted the performance of most plants, and moisture could modify the effect of BSCs on plants. The effect of BSCs on plant performance was related to seed traits and plant life stage and the presence of the BSC promotes the growth of the plants when it reaches the survival stage. In field observations, we found that the number of seedling species was lower on BSCs compared to bare lands and that the number of species on broken crusts was greater than on intact crusts; while seedling density on bare land was significantly higher than it in BSC patches. [ABSTRACT FROM AUTHOR]

One of the key goals of ecology is to understand how communities are assembled. The species co‐existence theory suggests that community β‐diversity is influenced by species pool and community assembly processes, such as environmental filtering, dispersal events, ecological drift and biotic interactions. However, it remains unclear whether there are similar β‐diversity patterns among different soil microbial groups and whether all these mechanisms play significant roles in mediating β‐diversity patterns. By conducting a broad survey across Chinese deserts, we aimed to address these questions by investing biological soil crusts (biocrusts). Through amplicon‐sequencing, we acquired β‐diversity data for multiple microbial groups, that is, soil total bacteria, diazotrophs, phoD‐harbouring taxa, and fungi. Our results have shown varying distance decay rates of β‐diversity across microbial groups, with soil total bacteria showing a weaker distance‐decay relationship than other groups. The impact of the species pool on community β‐diversity varied across microbial groups, with soil total bacteria and diazotrophs being significantly influenced. While the contributions of specific assembly processes to community β‐diversity patterns varied among different microbial groups, significant effects of local community assembly processes on β‐diversity patterns were consistently observed across all groups. Homogenous selection and dispersal limitation emerged as crucial processes for all groups. Precipitation and soil C:P were the key factors mediating β‐diversity for all groups. This study has substantially advanced our understanding of how the communities of multiple microbial groups are structured in desert biocrust systems. [ABSTRACT FROM AUTHOR]

Drylands are unique among terrestrial ecosystems in that they have a significant proportion of primary production facilitated by non‐vascular plants such as colonial cyanobacteria, moss, and lichens, i.e., biocrusts, which occur on and in the surface soil. Biocrusts inhabit all continents, including Antarctica, an increasingly dynamic continent on the precipice of change. Here, we describe in‐situ field surveying and sampling, remote sensing, and modeling approaches to assess the habitat suitability of biocrusts in the Lake Fryxell basin of Taylor Valley, Antarctica, which is the main site of the McMurdo Dry Valleys Long‐Term Ecological Research Program. Soils suitable for the development of biocrusts are typically wetter, less alkaline, and less saline compared to unvegetated soils. Using random forest models, we show that gravimetric water content, electrical conductivity, and snow frequency are the top predictors of biocrust presence and biomass. Areas most suitable for the growth of dense biocrusts are soils associated with seasonal snow patches. Using geospatial data to extrapolate our habitat suitability model to the whole basin predicts that biocrusts are present in 2.7 × 105 m2 and contain 11–72 Mg of aboveground carbon, based on the 90% probability of occurrence. Our study illustrates the synergistic effect of combining field and remote sensing data for understanding the distribution and biomass of biocrusts, a foundational community in the carbon balance of this region. Extreme weather events and changing climate conditions in this region, especially those influencing snow accumulation and persistence, could have significant effects on the future distribution and abundance of biocrusts and therefore soil organic carbon storage in the McMurdo Dry Valleys. [ABSTRACT FROM AUTHOR]

Biocrusts determine soil stability and resiliency, with a special role played by oxygenic photoautotrophic microorganisms in these communities. We evaluated temporal and geographic trends in studies focused on these microorganisms in biocrusts. Two databases were surveyed to obtain scientific articles published from 1998 to 2020 containing the terms 'biocrusts,' 'algae,' and 'cyanobacteria.' Although interest in biocrusts has increased recently, their ecological importance is still little explored. The scientific articles that mentioned a species list of cyanobacteria and/or algae revealed a very heterogeneous geographic distribution of research. Biocrusts have not been explored in many regions and knowledge in the tropics, where these communities showed high species richness, is limited. Geographic gaps were detected and more detailed studies are needed, mainly where biocrust communities are threatened by anthropogenic impacts. Aiming to address these knowledge gaps, we assembled a taxonomic list of all algae and cyanobacteria found in these articles, including information on their occurrence and ecology. This review is an updated global taxonomic survey of biocrusts, which importantly reveals their high species richness of oxygenic photoautotrophic microorganisms. We believe this database will be useful to future research by providing valuable taxonomic and biogeographic information regarding algae and cyanobacteria in biocrusts. [ABSTRACT FROM AUTHOR]