Plasmodesmata dynamics in bryophyte model organisms: secondary formation and developmental modifications of structure and function.

MAIN CONCLUSION: Developing bryophytes differentially modify their plasmodesmata structure and function. Secondary plasmodesmata formation via twinning appears to be an ancestral trait. Plasmodesmata networks in hornwort sporophyte meristems resemble those of angiosperms. All land-plant taxa use plasmodesmata (PD) cell connections for symplasmic communication. In angiosperm development, PD networks undergo an extensive remodeling by structural and functional PD modifications, and by postcytokinetic formation of additional secondary PD (secPD). Since comparable information on PD dynamics is scarce for the embryophyte sister groups, we investigated maturating tissues of Anthoceros agrestis (hornwort), Physcomitrium patens (moss), and Marchantia polymorpha (liverwort). As in angiosperms, quantitative electron microscopy revealed secPD formation via twinning in gametophytes of all model bryophytes, which gives rise to laterally adjacent PD pairs or to complex branched PD. This finding suggests that PD twinning is an ancient evolutionary mechanism to adjust PD numbers during wall expansion. Moreover, all bryophyte gametophytes modify their existing PD via taxon-specific strategies resembling those of angiosperms. Development of type II-like PD morphotypes with enlarged diameters or formation of pit pairs might be required to maintain PD transport rates during wall thickening. Similar to angiosperm leaves, fluorescence redistribution after photobleaching revealed a considerable reduction of the PD permeability in maturating P. patens phyllids. In contrast to previous reports on monoplex meristems of bryophyte gametophytes with single initials, we observed targeted secPD formation in the multi-initial basal meristems of A. agrestis sporophytes. Their PD networks share typical features of multi-initial angiosperm meristems, which may hint at a putative homologous origin. We also discuss that monoplex and multi-initial meristems may require distinct types of PD networks, with or without secPD formation, to control maintenance of initial identity and positional signaling.

Moss species and precipitation mediate experimental warming stimulation of growing season N2 fixation in subarctic tundra.

Climate change in high latitude regions leads to both higher temperatures and more precipitation but their combined effects on terrestrial ecosystem processes are poorly understood. In nitrogen (N) limited and often moss-dominated tundra and boreal ecosystems, moss-associated N2 fixation is an important process that provides new N. We tested whether high mean annual precipitation enhanced experimental warming effects on growing season N2 fixation in three common arctic-boreal moss species adapted to different moisture conditions and evaluated their N contribution to the landscape level. We measured in situ N2 fixation rates in Hylocomium splendens, Pleurozium schreberi and Sphagnum spp. from June to September in subarctic tundra in Sweden. We exposed mosses occurring along a natural precipitation gradient (mean annual precipitation: 571-1155 mm) to 8 years of experimental summer warming using open-top chambers before our measurements. We modelled species-specific seasonal N input to the ecosystem at the colony and landscape level. Higher mean annual precipitation clearly increased N2 fixation, especially during peak growing season and in feather mosses. For Sphagnum-associated N2 fixation, high mean annual precipitation reversed a small negative warming response. By contrast, in the dry-adapted feather moss species higher mean annual precipitation led to negative warming effects. Modelled total growing season N inputs for Sphagnum spp. colonies were two to three times that of feather mosses at an area basis. However, at the landscape level where feather mosses were more abundant, they contributed 50% more N than Sphagnum. The discrepancy between modelled estimates of species-specific N input via N2 fixation at the moss core versus ecosystem scale, exemplify how moss cover is essential for evaluating impact of altered N2 fixation. Importantly, combined effects of warming and higher mean annual precipitation may not lead to similar responses across moss species, which could affect moss fitness and their abilities to buffer environmental changes.

Vertical transport velocity of fine particles of aluminum smelter emissions.

In this study, the average values of vertical velocity of particles emitted from an aluminum smelter in the surface layer of the atmosphere were estimated using a semi-empirical method. The method is based on regression analysis of the horizontal profile of pollutants measured along the selected direction using moss bioindicators. The selection of epiphytic mosses Sanionia uncinata was carried out in 2013 in the zone of influence of a metallurgical industry enterprise in the city of Kandalaksha, Murmansk region. The concentrations of As, Si, Ni, Zn, Ti, Cd, Na, Pb, Co, K, Ba, Ca, Mg, Mn, Sr, Fe, Al, V, Cr, Cu were determined using atomic emission spectrometry. The conducted assessments showed that the average particle velocity toward the Earth's surface, when considering large spatial and temporal scales, is tens of times higher than gravitational settling velocities.

Complete Organelle Genome of the Desiccation-Tolerant (DT) Moss Tortula atrovirens and Comparative Analysis of the Pottiaceae Family.

Tortula atrovirens (Sm.) Lindb. is an important component of biological soil crusts and possesses an extraordinary tolerance against desiccation in dryland habitats. However, knowledge of the organelle genome of this desiccation-tolerant (DT) moss is still lacking. Here, we assembled the first reported Tortula organelle genome and conducted a comprehensive analysis within the Pottiaceae family. T. atrovirens exhibited the second largest chloroplast genome (129,646 bp) within the Pottiaceae, whereas its mitogenome (105,877 bp) and those of other mosses were smaller in size compared to other land plants. The chloroplast and mitochondrial genomes of T. atrovirens were characterized by the expansion of IR boundaries and the absence of homologous recombination-mediated by large repeats. A total of 57 RNA editing sites were detected through mapping RNA-seq data. Moreover, the gene content and order were highly conserved among the Pottiaceae organelle genomes. Phylogenetic analysis showed that bryophytes are paraphyletic, with their three lineages (hornworts, mosses, and liverworts) and vascular plants forming successive sister clades. Timmiella anomala is clearly separated from the monophyletic Pottiaceae, and T. atrovirens is closely related to Syntrichia filaris within the Pottioideae. In addition, we detected four hypervariable regions for candidate-molecular markers. Our findings provide valuable insights into the organelle genomes of T. atrovirens and the evolutionary relationships within the Pottiaceae family, facilitating future discovery of DT genetic resources from bryophytes.

Light drives nitrogen fixation in tropical montane cloud forests in Costa Rica.

Tropical montane cloud forests are high altitude ecosystems characterized by very high ambient humidity, which favors organisms that depend on the environment for their water status, such as bryophytes and their nitrogen-fixing symbionts. Bryophyte-associated N2 fixation is a major source of new N in several northern environments, but their contributions to the N cycle in other ecosystems is still poorly understood. In this work, we evaluated N2 fixation rates associated with epiphytic bryophytes growing along the stems of pumpwood trees (Cecropia sp.) as well as in surrounding litter and soil from a primary and a secondary cloud forests in the Talamanca Mountain Range, Costa Rica. Nitrogen fixation was significantly higher in substrates from the secondary forest compared to those from the primary forest. Overall, N2 fixation rates associated with epiphytic bryophytes were 57 times those of litter and 270 times what was measured in soil. Further, light intensity was the major factor influencing N2 fixation rates in all substrates. Increased access to light in disturbed cloud forests may therefore favor bryophyte-associated N2 fixation, potentially contributing to the recovery of these ecosystems.

Interactions between biocrusts and herbaceous communities are divergent in dry and wet semiarid ecosystems.

Biocrusts are a prevalent form of living cover in worldwide drylands, and their presence are intimately associated with herbaceous community, forming a spatially mosaic distribution pattern in dryland ecosystems. The role of biocrusts as modulators of herbaceous community assembly is extensively studied, whereas, less is known whether their interactions are permanent or changeable with various environmental conditions. This study conducted a field survey of herbaceous community accompanied by three types of biocrusts (cyanobacterial, cyanobacterial-moss mixed, and moss crusts) in two contrasting (dry and wet) semiarid climate regions in the Chinese Loess Plateau, to explore whether or not climatic aridity gradient affects the interactions between biocrusts and herbaceous community. Our results showed that in dry semiarid climate, the biomass, species richness, and diversity of herbaceous community from biocrust plots were 89 %, 179 %, and 52 % higher than that from the uncrusted plots, respectively, while in wet semiarid climate, those herbaceous community indices from biocrust plots were 68 %, 43 %, and 23 % lower than that from the uncrusted plots, respectively. The impacts of biocrusts on herbaceous community were highly dependent on the types and coverage of biocrusts. Regardless of aridity gradient, the richness and diversity of herbaceous community were the lowest in the moss-covered plots, followed by the cyanobacteria-covered plots and the plots with a mixed cyanobacteria and moss population. Along with increasing biocrust coverage, the species richness and diversity of herbaceous plants initially increased and then decreased in dry semiarid climate, while in wet semiarid climate they decreased linearly with biocrust coverage. Structural equation modeling revealed that the factors of biocrust types and coverage affected herbaceous community indirectly through soil properties in dry semiarid climate, whereas in wet semiarid climate they directly affected herbaceous community through biotic interactions. Together, our findings indicated that cyanobacterial and moss biocrusts facilitate the development of herbaceous community in dry semiarid climate by increasing soil stability and nutrient levels, but in wet semiarid climate they restrict herbaceous plant growth through competing niche space. These results highlight the divergent relationships between biocrusts and herbaceous community across aridity gradient in dryland ecosystems, and this knowledge may be critically important in light of the projected global climate change which is going to change the aridity of global drylands.

Microscale is key to model current and future Maritime Antarctic vegetation.

Despite being one of the most pristine regions in the world, Antarctica is currently also one of the most vulnerable to climate change. Antarctic vegetation comprises mostly lichens and bryophytes, complemented in some milder regions of Maritime Antarctica by two vascular plant species. Shifts in the spatial patterns of these three main vegetation groups have already been observed in response to climate change, highlighting the urgent need for the development of comprehensive large-scale ecological models of the effects of climate change. Besides climate, Antarctic terrestrial vegetation is also strongly influenced by non-climatic microscale conditions related to abiotic and biotic factors. Nevertheless, the quantification of their importance in determining vegetation patterns remains unclear. The objective of this work was to quantify the importance of abiotic and biotic microscale conditions in determining the spatial cover patterns of the major functional types, lichens, vascular plants and bryophytes, explicitly determining the likely confinement of each functional type to the microscale conditions, i.e., their ecological niche. Microscale explained >60 % of the spatial variation of lichens and bryophytes and 30 % of vascular plants, with the niche analysis suggesting that each of the three functional types may be likely confined to specific microscale conditions in the studied gradient. Models indicate that the main microscale ecological filters are abiotic but show the potential benefits of including biotic variables and point to the need for further clarification of vegetation biotic interactions' role in these ecosystems. Altogether, these results point to the need for the inclusion of microscale drivers in ecological models to track and forecast climate change effects, as they are crucial to explain present vegetation patterns in response to climate, and for the interpretation of ecological model results under a climate change perspective.

Drivers of biogenic volatile organic compound emissions in hygrophytic bryophytes.

Bryophytes can both emit and take up biogenic volatile organic compounds (BVOCs) to and from the environment. Despite the scarce study of these exchanges, BVOCs have been shown to be important for a wide range of ecological roles. Bryophytes are the most ancient clade of land plants and preserve very similar traits to those first land colonisers. Therefore, the study of these plants can help understand the early processes of BVOC emissions as an adaptation to terrestrial life. Here, we determine the emission rates of BVOCs from different bryophyte species to understand what drives such emissions. We studied 26 bryophyte species from temperate regions that can be found in mountain springs located in NE Spain. Bryophyte BVOC emission presented no significant phylogenetic signal for any of the compounds analysed. Hence, we used mixed linear models to investigate the species-specific differences and eco-physiological and environmental drivers of bryophyte BVOC emission. In general, species-specific variability was the main factor explaining bryophyte BVOC emissions; but additionally, photosynthetic rates and light intensity increased BVOC emissions. Despite emission measurements reported here were conducted at 30°, and may not directly correspond to emission rates in natural conditions, most of the screened species have never been measured before for BVOC emissions and therefore this information can help understand the drivers of the emissions of BVOCs in bryophytes.

Biomonitoring of airborne microplastics and microrubbers in Shiraz, Iran, using lichens and moss.

HIGHLIGHTS: Microplastics (MPs) and microrubbers (MRs) determined in lichens and mosses around Shiraz. In lichens, MPs mainly thin fibres up to 1 MP g-1; MRs were < 0.1 MP g-1. In mosses, abundances were similar but with a greater fraction of larger, non-fibrous particles. Larger MPs and MRs decreased in abundance with distance and elevation from Shiraz. Around Shiraz, the common moss, Grimmia critina, would be the most suitable biomonitor. Lichens and mosses have been employed as biomonitors of atmospheric particulate pollutants, like metals and industrial solids, for many decades. Here, we evaluated the potential of nine species of crustose and foliose lichens and a widely distributed moss (Grimmia critina) to act as biomonitors of airborne microplastics (MPs) and microrubbers (MRs). About 200 lichens and 40 mosses were sampled across different altitudinal transects in the vicinity of Shiraz City, southwest Iran, and MPs and MRs were quantified and characterised after sample peroxidation. In most species of lichen, MP and MR abundance overall was < 1 g-1 and < 0.1 g-1, respectively, and the majority of plastics were fibres of < 10 µm in diameter and < 1000 µm in length. Respective weight normalised abundances of MPs and MRs were similar in G. critina, but there were greater proportions of both larger (> 1000 µm) and non-fibrous particles among the MPs. In both lichens and moss, there was a greater number of larger MPs and MRs at locations closest to and at the same elevation as Shiraz than at more distant and elevated locations, suggesting an inverse relationship between particle size and distance travelled. Among the lichens, members of the genus Acarospora, with their areolated form, appeared to act as the most suitable biomonitors for MPs and MRs. Overall, however, the wide distribution of the moss, G. crinita, and its ability to intercept and accumulate a broader range of sizes and shapes of MPs and MRs make this species a better choice, at least in the type of environment studied.

Dehydration and rehydration differently affect photosynthesis and volatile monoterpenes in bryophytes with contrasting ecological traits.

Bryophytes desiccate rapidly when relative humidity decreases. The capacity to withstand dehydration depends on several ecological and physiological factors. Volatile organic compounds (VOCs) may have a role in enhancing tolerance to desiccating bryophytes. However, the functions of VOCs in bryophytes have received little attention so far. We aimed to investigate the impact of a dehydration-rehydration treatment on primary carbon metabolism and volatile terpenes (VTs) in three bryophytes with contrasting ecological traits: Vessicularia dubyana, Porella platyphylla and Pleurochaete squarrosa. First, we confirmed the desiccation sensitivity gradient of the species. Under fully hydrated conditions, the photosynthetic rate (A) was inversely associated with stress tolerance, with a lower rate in more tolerant species. The partial recovery of A in P. platyphylla and P. squarrosa after rehydration confirmed the desiccation tolerance of these two species. On the other hand, A did not recover after rehydration in V. dubyana. Regarding VT, each species exhibited a distinct VT profile under optimum hydration, with the highest VT pool found in the more desiccation-sensitive species (V. dubyana). However, the observed species-specific VT pattern could be associated with the ecological habitat of each species. P. squarrosa, a moss of dry habitats, may synthesize mainly non-volatile secondary metabolites as stress-defensive compounds. On the other hand, V. dubyana, commonly found submerged, may need to invest photosynthetically assimilated carbon to synthesize a higher amount of VTs to cope with transient water stress occurrence. Further research on the functions of VTs in bryophytes is needed to deepen our understanding of their ecological significance.

Moss as a passive biomonitoring tool for the atmospheric deposition and spatial distribution pattern of toxic metals in an industrial city.

Anthropogenic pollution impacts human and environmental health, climate change, and air quality. Karabük, an industrial area from the Black Sea Region in northern Türkiye, is vulnerable to environmental pollution, particularly soil and air. In this research on methodological aspects, we analyzed the concentrations of six potential toxic metals in the atmospheric deposition of the city using the passive method of moss biomonitoring. The ground-growing terrestrial moss, Hypnum cupressiforme Hedw., was collected during the dry season of August 2023 at 20 urban points. The concentrations of Cr, Cu, Cd, Ni, Pb, and Co were determined in mosses by the ICP-MS method. Descriptive statistical analysis was employed to evaluate the status and variance in the spatial distribution of the studied metals, and multivariate analysis, Pearson correlation, and cluster analysis were used to investigate the associations of elements and discuss the most probable sources of these elements in the study area. Cd and Co showed positive and significant inter-element correlations (r > 0.938), representing an anthropogenic association mostly present in the air particles emitted from several metal plants. The results showed substantial impacts from local industry, manufactured activity, and soil dust emissions. Steel and iron smelter plants and cement factories are the biggest emitters of trace metals in the Karabük area and the primary sources of Cr, Cd, Ni, and Co deposition.

Antarctica's hidden mycoviral treasures in fungi isolated from mosses: A first genomic approach.

This study investigates the presence of mycoviruses in Antarctic fungi and elucidates their evolutionary relationships. To achieve this, we aligned mycoviral gene sequences with genomes of previously sequenced Antarctic endophytic fungi, made available by our research group and accessible via Joint Genome Institute. Our findings reveal that the most prevalent genetic regions in all endophytic fungi are homologous to Partitiviruses, Baculoviridae, and Phycodnaviridae. These regions display evidence of positive selection pressure, suggesting genetic diversity and the accumulation of nonsynonymous mutations. This phenomenon implies a crucial role for these regions in the adaptation and survival of these fungi in the challenging Antarctic ecosystems. The presence of mycoviruses in Antarctic endophytic fungi may indicate shared survival strategies between the virus and its host, shedding light on their evolutionary dynamics. This study underscores the significance of exploring mycoviruses within endophytic fungi and their contributions to genetic diversity. Future research avenues could delve into the functional implications of these conserved mycoviral genetic regions in Antarctic endophytic fungi, providing a comprehensive understanding of this intriguing association and genomic retention of viral region in fungi.

A review of 210Pb and 210Po in moss.

Among environment contaminants, 210Pb and 210Po have gained significant research attention due to their radioactive toxicity. Moss, with its exceptional adsorption capability for these radionuclides, serves as an indicator for environmental 210Pb and 210Po pollution. The paper reviews a total of 138 articles, summarizing the common methods and analytical results of 210Pb and 210Po research in moss. It elucidates the accumulation characteristics of 210Pb and 210Po in moss, discusses current research challenges, potential solutions, and future prospects in this field. Existing literature indicates limitations in common measurement techniques for 210Pb and 210Po in moss, characterized by high detection limits or lengthy sample processing. The concentration of 210Pb and 210Po within moss display substantial variations across different regions worldwide, ranging from

One year of active moss biomonitoring in the identification of PAHs in an urbanized area-prospects and implications.

Classical monitoring of air pollution provides information on environmental quality but involves high costs. An alternative to this method is the use of bioindicators. The purpose of our work was to evaluate atmospheric aerosol pollution by selected polycyclic aromatic hydrocarbons conducted as part of annual active biomonitoring ("moss-bag" technique) with the use of three moss species: Pleurozium schreberi, Sphagnum fallax, and Dicranum polysetum. The gas chromatography-mass spectrometry (GC-MS) was utilized to determine certain 13 polycyclic aromatic hydrocarbons (PAHs). Three seasonal variations in PAH concentrations have been observed as a result of the study. A fire on the toilet paper plant caused an increase of five new compounds: benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP), indeno(1.2.3)-cd_pyrene (IP), dibenzo(a.h)anthracene (Dah), and benzo(g.h.i)perylene (Bghi) in proximity after 8 months of exposure compared to previous months. The effect of meteorological conditions on the deposition of PAHs (mainly wind direction) in mosses was confirmed by principal component analysis (PCA). Dicranum polysetum moss accumulated on average 26.5% more PAHs than the other species, which allows considering its broader use in active biomonitoring. The "moss-bag" technique demonstrates its feasibility in assessing the source of PAH air pollution in a long-term study. It is recommended to use this biological method as a valuable tool in air quality monitoring.

What potential do mosses have as biomonitors of POPs? A comparative study of hexachlorocyclohexane sorption.

Persistent organic pollutants (POPs) pose a significant global threat to human health and the environment, and require continuous monitoring due to their ability to migrate long distances. Active biomonitoring using cloned mosses is an inexpensive but underexplored method to assess POPs, mainly due to the poor understanding of the loading mechanisms of these pollutants in mosses. In this work, Fontinalis antipyretica (aquatic moss) and Sphagnum palustre (terrestrial moss) were evaluated as potential biomonitors of hexachlorocyclohexanes (HCHs: α-, ß-, γ-, δ-HCH), crucial POPs. Moss clones, grown in photobioreactors and subsequently oven-dried, were used. Their lipid composition and distribution were characterized through molecular and histochemical studies. Adsorption experiments were carried out in the aqueous phase using the repeated additions method and in the gas phase using an active air sampling technique based on solid-phase extraction, a pioneering approach in moss research. F. antipyretica exhibited greater lipid content in the walls of most cells and higher adsorption capacity for all HCH isomers in both gaseous and liquid environments. These findings highlight the need for further investigation of POP loading mechanisms in mosses and open the door to explore other species based on their lipid content.

Habitat conditions and not moss composition mediate microbial community structure in Swiss peatlands.

Peatlands, one of the oldest ecosystems, globally store significant amounts of carbon and freshwater. However, they are under severe threat from human activities, leading to changes in water, nutrient and temperature regimes in these delicate systems. Such shifts can trigger a substantial carbon flux into the atmosphere and diminish the water-holding capacity of peatlands. Microbes associated with moss in peatlands play a crucial role in providing these ecosystem services, which are at risk due to global change. Therefore, understanding the factors influencing microbial composition and function is vital. Our study focused on five peatlands along an altitudinal gradient in Switzerland, where we sampled moss on hummocks containing Sarracenia purpurea. Structural equation modelling revealed that habitat condition was the primary predictor of community structure and directly influenced other environmental variables. Interestingly, the microbial composition was not linked to the local moss species identity. Instead, microbial communities varied significantly between sites due to differences in acidity levels and nitrogen availability. This finding was also mirrored in a co-occurrence network analysis, which displayed a distinct distribution of indicator species for acidity and nitrogen availability. Therefore, peatland conservation should take into account the critical habitat characteristics of moss-associated microbial communities.

A method for studying the influence of Mn oxyhydroxides on the trace element content of aquatic bryophytes.

The main objective of this study was to develop and test a method of separating externally deposited Mn oxyhydroxides and co-precipitated elements from samples of aquatic moss (the moss Fontinalis antipyretica). The method, which uses 0.1 M hydroxylamine to dissolve the oxyhydroxides, was tested with samples collected in rivers with slightly acidic, well­oxygenated waters, where high rates of Mn precipitation occur. The method was effective (it extracted up to 84 % of the Mn) and selective (Fe oxyhydroxides were not extracted). The elements Ba, Cd, Zn and Ni were associated with the Mn oxyhydroxides, while Al, As, Cr, Cu, Fe, Hg and Pb were not. Deposition of Mn therefore increased the concentration of some elements in the moss samples. However, as Mn precipitation depends on Eh and pH, which are independent of the concentrations of the elements in water, the relationship between water and moss element concentrations is not clear (i.e. the data are noisy). This is a problem in biomonitoring studies, which assume a close relationship between element concentrations in moss and water. The value of the proposed extraction method is that it can be used to correct the effect of Mn deposition. We present an example of this correction applied to the Cd concentrations in the test data. We found that the noise introduced by the Mn, including age-related effects (observed by comparing concentrations in 0-2.5 and 2.2-5.0 cm sections from the shoot apex), can be reduced. Additionally, the correction revealed recent increases in Cd concentrations in one site that were not observed in the uncorrected data. Another finding of interest was the low content of total Mn and different extractability (of most elements) observed in moss samples collected in alkaline waters. Finally, we discuss how future studies designed for different environmental scenarios can benefit from application of the proposed method.

Growth physiology and chlorophyll fluorescence analysis of two moss species under different LED light qualities.

This study investigated the responses of Didymodon constrictus and Hypnum plumaeforme to different light qualities emitted by light-emitting diodes (LEDs), including white light (WL), red light (RL), blue light (BL), yellow light (YL), green light (GL), and a combination of red and blue light (R1B1L). The research analyzed the fluorescence imaging, photosynthetic pigments, coloration, and growth characteristics related to antioxidant enzymes in these two moss species. The results indicated that R1B1L significantly enhanced the content of photosynthetic pigments, maximum relative electron transport rate (rETRmax), saturation light intensity (IK), and the greenness of the moss. RL improved the maximum quantum yield (Fv/Fm), the light energy efficiency of H. plumaeforme and effective quantum yield in both moss species. In contrast, BL notably increased non-photochemical quenching (NPQ), photochemical quenching (qp), and the steady-state fluorescence decrease ratio (RFD) in H. plumaeforme. The application of GL significantly increases the maximum photon yield (Fv/Fm) in D. constrictus, as well as the light energy efficiency and elongation length, resulting in a shift in the color composition of both moss species towards yellow. Among the light treatments, R1B1L had the highest induction rate and promotional effect on the growth of both moss species. These mosses absorbed GL and RL effectively, while BL played a crucial role in the dissipation of heat and electron transfer in H. plumaeforme. This research provides valuable insights for the regulation of LED light environments and the physiological adaptability of moss in artificial cultivation.

Characteristics of spatial and temporal variability in the distribution of biological soil crusts on the Loess Plateau, China.

Biological soil crust (biocrust) is widely distributed on the Loess Plateau and plays multiple roles in regulating ecosystem stability and multifunctionality. Few reports are available on the distribution characteristics of biocrust in this region, which limits the assessment of its ecological functions. Based on 388 sampling points in different precipitation zones on the Loess Plateau from 2009 to 2020, we analyzed the coverage, composition, and influencing factors of biocrust across different durations since land abandonment, precipitation levels, topography (slope aspect and position), and utilization of abandoned slopelands (shrubland, forest, and grassland). On this base, with the assistance of machine learning and spatial modeling methods, we generated a distribution map of biocrust and its composition at a resolution of 250 m × 250 m, and analyzed the spatial distribution of biocrust on the Loess Plateau. The results showed that the average biocrust coverage in the woodlands and grasslands was 47.3%, of which cyanobacterial crust accounted for 25.5%, moss crust 19.7%, and lichen crust 2.1%. There were significant temporal and spatial variations. Temporally, the coverage of biocrust in specific regions fluctuated with the extension of the abandoned durations and coverage of cyanobacterial crust, while moss crust showed a reverse pattern. In addition, the coverage of biocrust in the wet season was slightly higher than that in the dry season within a year. Spatially, the coverage of biocrusts on the sandy lands area on the Loess Plateau was higher and dominated by cyanobacterial crusts, while the coverage was lower in the hilly and gully area. Precipitation and utilization of abandoned land were the major factors driving biocrust coverage and composition, while slope direction and position did not show obvious effect. In addition, soil organic carbon content, pH, and texture were related to the distribution of biocrust. This study uncovered the spatial and temporal variability of biocrust distribution, which might provide important data support for the research and management of biocrust in the Loess Plateau region.

Impact of changing climate on bryophyte contributions to terrestrial water, carbon, and nitrogen cycles.

Bryophytes, including the lineages of mosses, liverworts, and hornworts, are the second-largest photoautotroph group on Earth. Recent work across terrestrial ecosystems has highlighted how bryophytes retain and control water, fix substantial amounts of carbon (C), and contribute to nitrogen (N) cycles in forests (boreal, temperate, and tropical), tundra, peatlands, grasslands, and deserts. Understanding how changing climate affects bryophyte contributions to global cycles in different ecosystems is of primary importance. However, because of their small physical size, bryophytes have been largely ignored in research on water, C, and N cycles at global scales. Here, we review the literature on how bryophytes influence global biogeochemical cycles, and we highlight that while some aspects of global change represent critical tipping points for survival, bryophytes may also buffer many ecosystems from change due to their capacity for water, C, and N uptake and storage. However, as the thresholds of resistance of bryophytes to temperature and precipitation regime changes are mostly unknown, it is challenging to predict how long this buffering capacity will remain functional. Furthermore, as ecosystems shift their global distribution in response to changing climate, the size of different bryophyte-influenced biomes will change, resulting in shifts in the magnitude of bryophyte impacts on global ecosystem functions.