Search Results (250)

Lichens, complex symbiotic associations between fungi and photosynthetic partners, are widespread in terrestrial ecosystems but remain poorly studied in tropical dry forests (TDFs). This review synthesizes current knowledge on the diversity, ecological roles, adaptive traits, and ethnobotanical uses of lichens in TDFs, with a focus on the Neotropics. As most lichens discussed here are crustose species that inhabit tree bark, this paper also provides a thoughtful review of the origin, distribution, and highly heterogeneous floristic composition of TDFs, which directly shape lichen habitats. It discusses how lichens have evolved to cope with seasonal water stress, emphasizing desiccation tolerance as a key feature of the symbiosis. This review also explores lichen community composition, interactions with host trees, microclimatic conditions, herbivory, and soil crust formation. Despite evidence of high species richness, functional diversity, and ecological importance, lichens in TDFs are largely overlooked in conservation strategies. Moreover, several regions remain vastly understudied, and many species likely remain undescribed. Ethnolichenological practices, though scarce, underscore the cultural and medicinal value of these organisms. Given the high rates of habitat loss and endemism in TDFs, there is a pressing need to expand research on lichen diversity and to investigate the evolutionary origins of their survival strategies. The conservation of these lichens is inseparable from the conservation of TDFs themselves. Understanding how lichens adapt to the harsh and variable conditions of TDFs is essential for integrating them into biodiversity conservation and ecosystem restoration frameworks. Full article

The surface of the Great Wall harbors a large number of non-vascular plants dominated by cyanobacteria, lichens and mosses as well as microorganisms, and form biocrusts by cementing with the soils and greatly alters the pore structure of the soil and the ecohydrological processes associated with the soil pore space, and thus influences the soil resistance to erosion. However, the microscopic role of the biocrusts in influencing the pore structure of the surface of the Great Wall is not clear. This study chose the Warring States Qin Great Wall in Weiyuan, Gansu Province, China, as research site to quantify thepore structure characteristics of the three-dimensional of bare soil, cyanobacterial-lichen crusts, and moss crusts at the depth of 0–50 mm, by using optical microscopy, scanning electron microscopy, and X-ray computed tomography and image analysis, and the precipitation infiltration process. The results showed that the moss crust layer was dominated by large pores with long extension and good connectivity, which provided preferential seepage channels for precipitation infiltration, while the connectivity between the cyanobacterial-lichen crust voids was poor; The porosity of the cyanobacterial-lichen crust and the moss crust was 500% and 903.27% higher than that of the bare soil, respectively. The porosity of the subsurface layer of cyanobacterial-lichen crust and moss crust was significantly lower than that of the biocrusts layer by 92.54% and 97.96%, respectively, and the porosity of the moss crust was significantly higher than that of the cyanobacterial-lichen crust in the same layer; Cyanobacterial-lichen crusts increased the degree of anisotropy, mean tortuosity, moss crust reduced the degree of anisotropy, mean tortuosity. Biocrusts increased the fractal dimension and Euler number of pores. Compared with bare soil, moss crust and cyanobacterial-lichen crust increased the isolated porosity by 2555% and 4085%, respectively; Biocrusts increased the complexity of the pore network models; The initial infiltration rate, stable infiltration rate, average infiltration rate, and the total amount of infiltration of moss crusted soil was 2.26 and 3.12 times, 1.07 and 1.63 times, respectively, higher than that of the cyanobacterial-lichen crusts and the bare soil, by 1.53 and 2.33 times, and 1.13 and 2.08 times, respectively; CT porosity and clay content are significantly positively correlated with initial soil infiltration rate (|r| ≥ 0.85), while soil type and organic matter content are negatively correlated with initial soil infiltration rate. The soil type and bulk density are directly positively and negatively correlated with CT porosity, respectively (|r| ≥ 0.52). There is a significant negative correlation between soil clay content and porosity (|r| = 0.15, p < 0.001). Biocrusts alter the erosion resistance of rammed earth walls by affecting the soil microstructure of the earth’s great wall, altering precipitation infiltration, and promoting vascular plant colonisation, which in turn alters the erosion resistance of the wall. The research results have important reference for the development of disposal plans for biocrusts on the surface of archaeological sites. Full article

Microorganisms (bacteria and algae) are important components of biological soil crusts, which exhibit crucial functions in promoting plant growth, maintaining soil structure, and improving soil nutrient content. To determine the effects of combined inoculation on the growth of Poa annua and sandy soils, four species of bacteria and algae were isolated and identified from biological soil crusts (during different developmental stages in a karst rocky desertification area). The soil quality was evaluated based on a soil quality index (SQI), growth indicators of Poa annua, soil physicochemical properties, and a stability analysis of aggregates. With the application of nutrient-poor sandy soils as the substrate, different treatment inoculation solutions were inoculated onto Poa annua. The results revealed that bacteria–algal co-inoculation reduces soil acidity, enhances soil nutrient content and aggregate stability, improves soil quality, and protects plant growth. Notably, compared with the single application of bacterial solution and algal solution, the combined application of bacteria–algal solution significantly improves the sandy soil quality. Full article

In the process of the work of a coal power station is formed ash and slag, which, along with process water, are deposited in the dumps. Coal ash waste dumps significantly degrade the surrounding environment due to their unprotected surfaces, which are highly susceptible to wind and water erosion. This results in the dispersion of contaminants into adjacent ecosystems. Pollutants migrate into terrestrial and aquatic systems, compromising soil quality and water resources, and posing documented risks to the environment and human health. Primary succession on the coal ash dumps of the Apatity thermal power plant (Murmansk Region, NW Russia) was initiated by cyanobacterial colonization. We studied cyanobacterial communities inhabiting three spoil sites that varied in time since decommissioning. These sites are characterized by exceptionally high concentrations of calcium and magnesium oxides—levels approximately double those found in the region’s natural soils. A total of 18 cyanobacterial taxa were identified in disposal sites. Morphological analysis of visible surface crusts revealed 16 distinct species. Furthermore, 24 cyanobacterial strains representing 11 species were successfully isolated into unialgal culture and tested with a molecular genetic approach to confirm their identification from 16S rRNA. Three species were determined with molecular evidence. Cyanobacterial colonization of coal fly ash disposal sites begins immediately after deposition. Primary communities initially exhibit low species diversity (four taxa) and do not form a continuous ground cover in the early years. However, as succession progresses—illustrated by observations from a 30-year-old deposit—spontaneous surface revegetation occurs, accompanied by a marked increase in cyanobacterial diversity, reaching 12 species. Full article

Basalt is prevalent in the Earth’s crust and makes up about 90% of all volcanic rocks. The earth is warming at an alarming rate, and there is a search for a long-term solution to this problem. Geologic carbon storage in basalt offers an effective and durable solution for carbon dioxide sequestration. Basaltic rocks are widely used for road and building construction and insulation, soil amendment, and in carbon storage. There is a need to understand the parameters that affect this process in order to achieve efficient carbon mineralization. This review systematically analyzes peer-reviewed studies and project reports published over the past two decades to assess the mechanisms, effectiveness, and challenges of carbon mineralization in basaltic formations. Key factors such as mineral composition, pH, temperature and pressure are evaluated for their impact on mineral dissolution and carbonate precipitation kinetics. The presence of olivine and basaltic glass also accelerates cation release and carbonation rates. The review includes case studies from major field projects (e.g., CarbFix and Wallula) and laboratory experiments to illustrate how mineralization performs in different geological environments. It is essential to maximize mineralization kinetics while ensuring the formation of stable carbonate phases in order to achieve efficient and permanent carbon dioxide storage in basaltic rock. Full article

This study investigates the weathering crust composite of serpentine, pyroxenite and granite in the Niangniangmiao area, the weathering crusts inside and outside the mining area were compared respectively, systematically revealing the distribution patterns, migration pathways, and ecological element activity characteristics of high-background elements (e.g., chromium (Cr) and nickel (Ni)) through precise sampling, the Tessier five-step sequential extraction method, and a migration coefficient model. Key findings include: (1) Element distribution and controlling mechanisms: The average Cr and Ni contents in the serpentinite profile are significantly higher than those in pyroxenite. However, the semi-weathered pyroxenite layer exhibits an inverted Cr enrichment ratio in relation to serpentinite, 1.8× and 1.2×, respectively, indicating that mineral metasomatic sequences driven by hydrothermal alteration dominate element differentiation; the phenomenon of inverted enrichment of high-background elements occurs in the weathering crust profiles of the two basic rocks. (2) Dual impacts of mining activities on heavy metal enrichment: Direct mining increases topsoil Cr content in serpentinite by 40% by disrupting parent material homology, while indirect activities introduce exogenous Zn and Cd (Spearman correlation coefficients with Cr/Ni are from ρ = 0.58 to ρ = 0.72). Consequently, the bioavailable fraction ratio value of Ni outside the mining area (21.14%) is significantly higher than that within the area (14.30%). (3) Element speciation and ecological element activity: Over 98% of Cr in serpentine exists in residual fractions, whereas the Fe-Mn oxide-bound fraction (F3) of Cr in extra-mining pyroxenite increases to 5.15%. The element activity in ecological systems ranking of Ni in soil active fractions (F1 + F2 = 15%) follows the order: granite > pyroxenite > serpentine. Based on these insights, a scientific foundation for targeted remediation in high-background areas (e.g., prioritizing the treatment of semi-weathered pyroxenite layers) can be provided. Full article

Soil degradation has been accelerating globally due to climate change, which threatens food production, biodiversity, and ecosystem balance. Traditional soil restoration strategies are often expensive, slow, or unsustainable in the long term. In this context, cyanobacteria have emerged as promising biotechnological alternatives, being the only prokaryotes capable of performing oxygenic photosynthesis. Moreover, they can capture atmospheric carbon and nitrogen, release exopolysaccharides (EPSs) that stabilize the soil, and facilitate the development of biological soil crusts (biocrusts). In recent years, the convergence of multi-omics tools, such as metagenomics, metatranscriptomics, and metabolomics, has advanced our understanding of cyanobacterial dynamics, their metabolic potential, and symbiotic interactions with microbial consortia, as exemplified by the cyanosphere of Microcoleus vaginatus. In addition, recent advances in bioinformatics have enabled high-resolution taxonomic and functional profiling of environmental samples, facilitating the identification and prediction of resilient microorganisms suited to challenging degraded soils. These tools also allow for the prediction of biosynthetic gene clusters and the detection of prophages or cyanophages within microbiomes, offering a novel approach to enhance carbon sequestration in dry and nutrient-poor soils. This review synthesizes the latest findings and proposes a roadmap for the translation of molecular-level knowledge into scalable biotechnological strategies for soil restoration. We discuss approaches ranging from the use of native biocrust strains to the exploration of cyanophages with the potential to enhance cyanobacterial photosynthetic activity. By bridging ecological functions with cutting-edge omics technologies, this study highlights the critical role of cyanobacteria as a nature-based solution for climate-smart soil management in degraded and arid ecosystems. Full article

Rare earth elements (REEs) are critical mineral resources that play a pivotal role in modern technology and industry. Currently, the global supply of light rare earth elements (LREEs) remains adequate. However, the supply of heavy rare earth elements (HREEs) is associated with substantial risks due to their limited availability. Ion-adsorption type rare earth deposits (IAREDs), which represent the predominant source of HREEs, have become a focal point for exploration activities, with a notable increase in global interest in recent years. This study systematically collected stream sediments and stream water samples from the Jiaping IARED in Guangxi, as well as from adjacent granitic and carbonate background areas, to investigate the exploration significance of geochemical surveys for IAREDs. Additionally, mineralized soil layers, non-mineralized soil layers, and bedrock samples from the weathering crust of the Jiaping deposit were analyzed. The results indicate that stream sediments originating from the Jiaping IARED and granite-hosted background regions display substantially elevated REE concentrations relative to those from carbonate-hosted background areas. Moreover, δEu values in stream sediments can serve as an effective indicator for differentiating weathering products derived from granitic and carbonate lithologies. Within the mining area, three coarse-grained fractions of stream sediments (i.e., +20 mesh, 20–60 mesh, and 60–150 mesh) exhibit REE concentrations comparable to those observed in both granite-hosted and carbonate-hosted background regions. However, the HREEs content in the finer -150-mesh stream sediments from Jiaping IARED is markedly higher than that in the two background regions. The (La/Sm)_N versus (La/Yb)_N ratios of -150-mesh stream sediments in the Jiaping IARED may reflect the mixing processes involving HREE-enriched ore layer, non-mineralized layer, and LREE-enriched ore layer. This observation implies that fine-grained (-150-mesh) stream sediments can partially inherit the REE characteristics of mineralized layers within IAREDs. Scanning electron microscopy (SEM) observations indicate that the enrichment of REEs in fine-grained stream sediments primarily originates from REE-rich accessory minerals derived from parent rocks and mineralized weathering crusts. A comparative analysis reveals that the concentrations of REEs in stream water collected during the rainy season are significantly higher than those collected during the dry season. Moreover, the levels of REEs, especially HREE, in stream water from the Jiaping IARED substantially exceed those in background areas. Collectively, these findings suggest that the geochemical signatures of REEs in rainy season stream water possess diagnostic potential for identifying IAREDs. In conclusion, the integrated application of geochemical surveys of stream water and -150-mesh stream sediments can effectively delineate exploration targets for IAREDs. Full article

This study explored the enzymatic formation of gel-like polymeric matrices through carbonate precipitation for dust suppression in Yellow River silt. The hydrogel-modified EICP method effectively enhanced the compressive strength and resistance to wind–rain erosion by forming a reinforced bio-cemented crust. The optimal cementation solution, consisting of urea and CaCl₂ at equimolar concentrations of 1.25 mol/L, was applied to improve CaCO₃ precipitation uniformity. A spraying volume of 4 L/m² (first urea-CaCl₂ solution, followed by urease solution) yielded a 14.9 mm thick hybrid gel-CaCO₃ crust with compressive strength exceeding 752 kPa. SEM analysis confirmed the synergistic interaction between CaCO₃ crystals and the gel matrix, where the hydrogel network acted as a nucleation template, enhancing crystal bridging and pore-filling efficiency. XRD analysis further supported the formation of a stable gel-CaCO₃ composite structure, which exhibited superior resistance to wind–rain erosion and mechanical wear. These findings suggest that gel-enhanced EICP represents a novel bio-gel composite technology for sustainable dust mitigation in silt soils. Full article

Biological soil crusts (referred to as biocrusts) constitute prominent components within the ecosystem of tropical coral islands in the South China Sea, covering approximately 6.25% of the island’s terrestrial surface. Biocrusts are the key to the restoration of the island ecosystem. It is widely acknowledged that phototrophic microorganisms profoundly contribute to biocrust formation and development. They provide fixed carbon and nitrogen and produce exopolysaccharides for the BSC ecosystems. Although aerobic anoxygenic phototrophic bacteria (AAPB) are an important functional group of phototrophic microorganisms, the community characteristics of AAPB in coral island biocrusts and their role in the formation of biocrusts have rarely been reported. In this study, we employed amplifications of the pufM gene to characterize the AAPB communities of biocrusts on a tropical coral island. The outcomes revealed a discernible augmentation in both the abundance and richness of AAPB concurrent with the formation of biocrusts, concomitantly with a decrement in diversity. Within the AAPB communities, the Pseudomonadota (Proteobacteria) phylum emerges as the prevailing dominion, indicating marked differentiations in terms of family and genus compositions between the biocrust and bare soil. Canonical correlation analysis has unveiled a robust and meaningful correlation between the AAPB composition and the attributes of the soil, including total nitrogen, total organic carbon, total phosphorus, pH, and calcium content. Furthermore, co-occurrence network patterns shift with biocrust formation, enhancing stability. Meanwhile, keystone taxa analysis revealed specific OTUs associated with each soil type, with genus Brevundimonas as the main group. Furthermore, pure-culture AAPB strains isolated from biocrusts exhibited a panorama of diversity, predominantly belonging to Pseudomonadota. Particularly, the Skermanella and Erythrobacter genera demonstrated strong exopolysaccharide secretion and sand-binding capabilities. This study sheds light on the significant functional role of AAPB in tropical coral island biocrusts, expanding our understanding of their contribution to ecosystem services, and providing valuable insights for ecological restoration efforts on coral islands. Full article

Nostoc flagelliforme, a filamentous cyanobacterium inhabiting desert biological soil crusts (BSCs), has developed exceptional strategies to endure extreme environmental stresses, including severe desiccation, intense ultraviolet (UV) radiation, and drastic temperature fluctuations. These organisms must effectively sense and predict environmental changes, particularly the onset of desiccation. This review explores recent advancements in the molecular mechanisms that enable N. flagelliforme to survive under such harsh conditions, with a focus on stress signal sensing, transduction pathways, and photosynthetic adjustments. Key molecular adaptations include the production of extracellular polysaccharide (EPS) sheaths for water retention, the accumulation of compatible solutes like trehalose, and the synthesis of UV-absorbing compounds such as scytonemin and mycosporine-like amino acids (MAAs). Furthermore, N. flagelliforme utilizes a complex signal transduction network, including light-sensing pathways, to regulate responses to rehydration and desiccation cycles. This review emphasizes the integrative nature of N. flagelliforme’s adaptive mechanisms and highlights their potential for biotechnological applications, such as enhancing drought tolerance in crops and advancing ecological restoration in arid regions. Full article

A typical county for traditional village conservation in China is Songyang County. It is renowned for its ancient rammed earth dwellings, which exhibit a unique microclimate and possess significant historical value. However, high precipitation and acid rain under the subtropical monsoon climate have caused severe surface erosion, including cracking and spalling. This study focuses on traditional rammed earth dwellings in Chenjiapeng Village, Songyang County, combining field surveys, experimental analysis, and microscopic characterization to systematically investigate erosion mechanisms and protection strategies. Techniques, such as drone aerial photography, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and microbial diversity detection, were employed to elucidate the anti-erosion mechanisms of gray–green biological crusts on rammed earth surfaces. The results indicate that algal crusts enhance surface compressive strength and shear resistance through macroscopic coverage (reducing raindrop kinetic energy and moisture retention) and microscopic extracellular polysaccharide-cemented soil particles forming a three-dimensional network. However, acidic environments induce metabolic acid release from algae, dissolving cementing materials and creating a “surface protection-internal damage” paradox. To address this, a “transparent film-biofiber-acid inhibition layer” composite biofilm design is proposed, integrating a biodegradable polylactic acid (PLA) mesh, algal attachment substrates, and calcium carbonate microparticles to dynamically neutralize acidic substances, achieving synergistic ecological protection and cultural heritage authenticity. This study provides innovative solutions for the anti-erosion protection of traditional rammed earth structures, emphasizing environmental compatibility and sustainability. Full article

Desertification, which may lead to land degradation, is a significant global ecological issue. Biological soil crusts (BSCs) can play a role in sand fixation, carbon sequestration, and the improvement in soil functions in the ecological restoration of sandy soil. Therefore, elucidating the responses of BSCs to afforestation measures in alpine sandy areas is necessary to guide vegetation configuration in sandy ecosystems and enhance the effectiveness of sand fixation measures to prevent desertification. Herein, we determined the physicochemical properties and enzyme activities of bare sand (no crust) and algal and moss crusts collected from four sites subjected to different afforestation measures, including Salix cheilophila + Populus simonii (WLYY), Salix psammophila + S. cheilophila (SLWL), Artemisia ordosica + Caragana korshinskii (SHNT), and C. korshinskii (NT80) plantations. High-throughput sequencing was also employed to analyze bacterial community structure in BSCs. The results revealed that fine particle contents in algal and moss crusts were higher than in bare sand. During the succession from bare sand to algae to moss crust, their enzymatic activities and water and nutrient contents tended to increase. And the diversity of bacterial communities changed little in the SLWL sample points, while the richness showed a trend of first decreasing and then increasing, but bacterial community richness and diversity first decreased and then increased at the other sites. Among the four measures, SLWL enhanced nutrient contents, enzyme activities, and bacterial community richness and diversity in BSCs relatively more effectively. Alkaline-hydrolyzable nitrogen and soil organic matter were the key factors impacting bacterial community structures in BSCs under the four afforestation measures. From the perspective of BSCs, the results can provide a reference for the prevention and control strategies of other alpine sandy soils. Full article

Rocky outcrops are harsh habitats that support specialized organisms and communities, including biocrusts, which play roles in soil stabilization, water retention, and nutrient cycling. Despite their importance, tropical biocrusts, particularly in granite-gneiss formations, remain underexplored. This study examines biocrust composition in a granite-gneiss outcrop in a rural landscape in Southeastern Brazil, identifying microhabitats and analyzing co-occurrence patterns and community structure. We recorded eleven bryophyte species and one diatom species, while six cyanobacteria, three charophytes, and two chlorophytes were identified at the genus level. They were found in shallow depressions, though termite mounds also served as an important microhabitat. The cyanobacterium Scytonema was the most prevalent taxon. The liverwort Riccia weinionis had the highest number of positive co-occurrences, associating with cyanobacteria and algae. Network analysis based on co-occurrence revealed that Scytonema and the mosses Anomobryum conicum and Bryum argenteum were the most connected taxa, crucial for ecological network stability. The moss Bryum atenense acted as a key intermediary, with the highest betweenness centrality—a measure of its role in linking taxa. These findings provide insights into tropical rocky outcrop biocrusts, shedding light on their composition and interactions. Furthermore, the co-occurrence patterns and key taxa connectivity uncovered provide insights into ecosystem stability and can guide ecological restoration strategies. Full article

In Thailand, mangrove forests form a major component of the Andaman coastal ecosystems in the southern provinces. However, studies on their microbial assemblage largely revolved around groups of bacteria, fungi, and eukaryotic microalgae, while the diversity of cyanobacteria in these regions remains almost unknown. This taxonomic study applied the polyphasic approach to examine seven cyanobacterial strains collected from different mangrove environments (including soil crust, tree bark, wood, and rock surface) across Ranong, Phang-Nga, and Phuket provinces. The comprehensive analysis combining morphology, ecology, 16S rRNA phylogenetic relationships, genetic identity, ITS secondary structure, and ITS dissimilarity resulted in the first records of the genera Picosynechococcus, Allocoleopsis, and Sirenicapillaria in Thailand, and led to the description of a new species, Picosynechococcus mangrovensis sp. nov. This new species was differentiated from the type species P. fontinalis based on the distinct 16S rRNA gene phylogenetic position, low 16S rRNA genetic similarity, its slightly halophilic nature, and ability to form pseudo-filaments with up to 160 cells. Our research significantly expands the documented cyanobacterial diversity of Southeast Asian mangrove ecosystems, establishing a critical foundation for future ecological and biotechnological investigations in these understudied yet vital tropical habitats. Full article