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Abstract To explore the taxon‐dependent contribution of dispersal limitation versus environmental filters to bryophyte assemblages. We investigated bryophytes and six environmental variables on 168 islands in the Thousand Island Lake,China. We compared the observed beta diversity with the expected values based on six null models (EE, EF, FE, FF, PE, and PF), detected the partial correlation of beta diversity with geographical distances. We quantified the contributions of spatial versus environmental variables and island isolation per se to species composition (SC) using variance partitioning. We modeled the species‐area relationships (SARs) for bryophytes and the other eight biotas. To explore the taxon‐dependent effects of spatial versus environmental filters on bryophytes, 16 taxa including five categories (total bryophytes, total mosses, liverworts, acrocarpous, and pleurocarpous mosses) and 11 species‐richest families were included in the analyses. The observed beta diversity values were significantly different from the predicted values for all 16 taxa. For all five categories, the observed partial correlations between beta diversity and geographical distance after controlling environmental effects were not only positive, but also significantly different from the predicted values based on the null models. Spatial eigenvectors are more important in shaping SC than environmental variables for all 16 taxa except Brachytheciaceae and Anomodontaceae. Spatial eigenvectors contributed more to SC variation in liverworts than in mosses and in pleurocarpous mosses than in acrocarpous mosses. The effects of island isolation on SC were significant for all five categories, highly varied at the family level. The z values of the SARs for the five bryophyte categories were all larger than those of the other eight biotas. In subtropical fragmented forests, dispersal limitation exerted significant, taxon‐dependent effects on bryophyte assemblages. It was dispersal limitation rather than environmental filtering that predominantly regulated the SC patterns of bryophytes.

There exists an obvious gap in our knowledge of the nuclear DNA amount of bryophytes, not only in terms of the low number of species represented, but also in systematic and geographic representation. In order to increase our knowledge of nuclear DNA amounts and variation patterns in bryophytes, and their potential phylogenetic significances and influences on phenotypes, we used flow cytometry to determine the DNA 1C values of 209 bryophyte accessions, which belong to 145 mosses and 18 liverworts collected from China, by using Physcomitrella patens as a standard. We quantified the differences in DNA 1C values among different orders and families and constructed a phylogenetic tree of 112 mosses with four gene sequences (nad5, rbcL, trnL-F, and 18S-ITS1-5.8S-ITS2-26S). DNA 1C values were mapped onto the phylogenetic tree to test a potential phylogenetic signal. We also evaluated the correlations of the DNA 1C value with the sizes of individuals, leaves, cells, and spores by using a phylogenetically controlled analysis. New estimates of nuclear DNA amounts were reported for 145 species. The DNA 1C values of 209 bryophyte accessions ranged from 0.422 pg to 0.860 pg, with an average value of 0.561 pg, and a 2.04-fold variation covered the extremes of all the accessions. Although the values are not significantly different (p = 0.355) between mosses (0.528 pg) and liverworts (0.542 pg), there are variations to varying extents between some families and orders. The DNA 1C value size exerts a positive effect on the sizes of plants, leaves, and cells, but a negative effect on spore size. A weak phylogenetic signal is detected across most moss species. Phylogenetic signals are comparatively strong for some lineages. Our findings show that bryophytes have very small and highly constrained nuclear DNA amounts. There are nucleotype effects of nuclear DNA amounts for bryophytes at the individual, organ, and cell levels. We speculate that smaller nuclear DNA amounts are advantageous for bryophytes in dry environments. Significant differences in the DNA 1C values among some moss families and orders, as well as phylogenetic signals for some lineages, imply that nuclear DNA amount evolution in mosses seems to be unidirectional.

Aim: To clarify whether (1) there are thresholds in the species–area–habitat relationship for bryophytes and potential mechanisms, (2) such thresholds vary among different bryophyte groups, and (3) choros is better than area or habitat alone in the prediction of SR. Location: Islands in central and southern Zhejiang, China. Methods: We investigated the species richness (SR) of five bryophyte groups (total bryophytes, total mosses, liverworts, acrocarpous mosses, and pleurocarpous mosses) and habitat types on 66 islands. By using four threshold models, the logarithmic and the power models, we quantified their SR–choros relationships (SKRs), species–area relationships (SARs), and species–habitat relationships (SHRs). We also conducted path analyses to detect the direct effects of area per se and habitat per se on the SR. Results: The AICc values of the SKR models were overall smaller than those of the respective SAR and SHR models. The left-horizontal two-threshold model was best for the SKRs. A phenomenon (the small-choros effect, SCE) in which SR independently varied choros below a given threshold was detected. The SCE thresholds were smaller in mosses than in liverworts and in acrocarpous mosses than in pleurocarpous mosses. No direct and positive effects of habitat per se on the SR were detected below choros thresholds for all five groups. Main conclusions: There were two thresholds and SCEs in the SKRs of all five bryophyte groups. The SCEs likely resulted from the elimination of the direct and positive effects of habitat diversity on the SR of the bryophytes on small choros islands. The SCE thresholds were high for species groups sensitive to environments. Choros was better than area or habitat alone in determining the SR of the bryophytes on continental islands.

Momilactones are diterpenoid phytoalexins with allelopathic functions, which have been found in the widely distributed bryophyte Calohypnum plumiforme. Clustered genes containing CpDTC1/HpDTC1, CpCYP970A14, CpCYP964A1, and CpMAS are involved in momilactone biosynthesis. Besides, momilactone concentration in C. plumiforme is affected by heavy metal treatment such as CuCl2. However, transcription factors which might regulate momilactone biosynthesis are unclear. WRKY transcription factors (TFs) regulate phytoalexin biosynthesis in many plant species. In this study, a systematic analysis of the WRKY TFs was performed according to the C. plumiforme genome. A total of 19 CpWRKY genes were identified and categorized into five subgroups based on their phylogenetic relationship. Conserved domain and motif analysis suggested that the WRKY domain was highly conserved, but there were some variations. Cis-acting elements and binding sites analysis implied that CpWRKY genes might be induced by stress and further regulate the biosynthesis of momilactones. Our study lays a foundation for further functional characterization of the candidate CpWRKY genes involved in the regulation of momilactone biosynthesis, and provides new strategies for increasing momilactone production.

Epiphytes, including vascular and non-vascular, constitute a large part of global plant biodiversity. Distribution of obligatory epiphytic bryophytes results from climate and local habitat conditions. The most important epiphytic bryophytes and at the same time poorly investigated and taxonomically problematic ones belong to the family Orthotrichaceae. Epiphytic mosses are also ideal organisms for species modelling, because of having no roots, they are highly dependent on external environmental conditions. For this purpose, we used the ecological niche modelling approach to define their potential distribution in China and adjacent areas and explore factors that shape this distribution. We used 617 occurrence records of 23 species from six genera within the Orthotrichaceae family. Our results suggest that the distribution of members of the Orthotrichaceae family is predominantly affected by bioclimatic variables, especially bio10 (mean temperature of the warmest quarter), bio15 (precipitation seasonality), bio18 (precipitation of the warmest quarter), bio19 (precipitation of the coldest quarter), bio9 (mean temperature of the driest quarter), and bio2 (mean diurnal range). However, the distribution of particular genera is ruled by a different set of those variables. The distribution of two genera (Leratia and Ulota) is also highly influenced by land cover (especially mixed/other trees), whereas human footprint shows a moderate contribution to models of three genera (Lewinskya, Orthotrichum, Nyholmiella). Based on the occupied climatic niche and distribution patterns, representatives of the studied family are divided into two groups. The ‘western-montane group‘ is characterised by lower temperatures and lower precipitation whereas the ‘eastern-lowland’ group‘ by more humid and warmer conditions.

The leaf photosynthetic capacity, leaf N partitioning, non-structural carbohydrate content, C, N, and P contents of endangered U. elongata seedlings exposed to different light intensities were compared in this study. The most favorable light condition for the survival and growth of U. elongata seedlings in the present study was 100% full sunlight, as this induced higher Pn, PNUE, PC, PR, PB, and NSC content relative to shade-treated seedlings. PNUE, PR, PC, and PB in U. elongata seedling leaves decreased under 40% and 10% full sunlight, while PL increased, indicating that shade increased the light capture efficiency of photosystem (PS) II but decreased electron transfer from PSII to PSI. Furthermore, leaf N content increased with shade intensity, revealing an adaptive strategy for poor light environments. Additionally, the smallest leaf biomass, Pn, WUE, and CE values and C:N and C:P ratios in stems and leaves were observed under 10% full sunlight. These results indicate that seedlings growing under 40% full sunlight will benefit U. elongata conservation.

Lewinskya graphiomitria (Müll. Hal. ex Beckett) F. Lara, Garilleti & Goffinet, hitherto considered a New Zealand endemic species, has recently been repeatedly found at different localities in China, thereby representing an intriguing example of a remote intercontinental disjunction among the bryophytes. Herein, the current distribution of this species is reviewed and mapped and its disjunct occurrence in the two widely separated areas is discussed. Maps showing the quantification of extrapolated projection areas for L. graphiomitria are also presented. A possible way of its migration from New Zealand to Asia or vice versa is explained.

A total of 46 species and two varieties of the traditionally interpreted genus Orthotrichum are currently known to occur in China. They represent five genera, including Orthotrichum (29 species), Lewinskya (14 species and two varieties), and Nyholmiella and Leratia that are represented by a single species each. The fifth genus Florschuetziella, also consisting of only one species, F. scaberrima, is an entirely neglected representative of the China’s moss flora. A list of all accepted taxa is presented and for each taxon all literature records and herbarium specimens are enumerated for provinces in which they have been recorded, and their distribution is mapped. A key to determination of Chinese orthotrichalean mosses is presented. A chronological list of 63 species and varieties and two designations, O. catagonioides and O. microsporum which have never been validly published, reported from China in the years 1892–2020 is presented. Four species, Orthotrichum brasii, O. hooglandii, O. elegans and O. gymnostomum are excluded from the bryoflora of China and Lewinskya affinis var. bohemica and Orthotrichum schimperi are recorded for the first time from this country. Phytogeography of the Chinese taxa of the orthotrichalean mosses is considered and they are grouped into eight phytogeographical elements and five sub-elements.

The distribution data of 18 categories (including 446 species) of bryophytes in 66 islands of the Zhoushan Archipelago, China were complied. By using the matrix temperature and the NODF metrics under six null models, we evaluated their nestedness levels and explored possible mechanisms to form nested distribution with partial Spearman correlation and the random placement model. The main results were as follows: 1) all the 18 categories of bryophytes exhibited a high degree of nestedness; 2) nestedness level was higher for mosses than liverworts, higher for acrocarpous mosses than pleurocarpous mosses, and also varied among families; 3) the nested distribution of bryophytes in the archipelago was not due to passive sampling, but mainly due to nested habitats and selectiveextinction; 4) spore size might be a factor linked to selective-colonization accounting for nestedness of some bryophyte categories; and 5) nestedness level was higher for families with a high proportion of generalists than those with a high proportion of specialists, the conservation of the latter should cover more islands (patches). [ABSTRACT FROM AUTHOR]

Lewinskya graphiomitria (Müll. Hal. ex Beckett) F. Lara, Garilleti & Goffinet, hitherto considered a New Zealand endemic species, has recently been repeatedly found at different localities in China, thereby representing an intriguing example of a remote intercontinental disjunction among the bryophytes. Herein, the current distribution of this species is reviewed and mapped and its disjunct occurrence in the two widely separated areas is discussed. Maps showing the quantification of extrapolated projection areas for L. graphiomitria are also presented. A possible way of its migration from New Zealand to Asia or vice versa is explained. [ABSTRACT FROM AUTHOR]

Understanding patch attributes influencing biological diversity in fragmented habitats is of critical importance for biodiversity conservation. We investigated the bryophytes and six patch attributes (habitat diversity, area, elevation, isolation degree, vegetation coverage, and shape irregularity) across 168 islands in the Thousand Island Lake (TIL), China. Multivariate analyses showed that the six patch attributes explained 68.1% of the species richness (SR) variation and 13.3% of the species composition (SC) variation. Habitat diversity explained 55.5% of the total SR variation (8.4% by habitat diversity per se and 47.1% confounded by the remaining variables). Although area, vegetation coverage, shape irregularity, and elevation independently explained only 0.4% to 2.4% of the total SR variation, respectively, a large part of their effects were confounded with the other patch attributes. All surveyed patch attributes imposed weak but significant influences on bryophyte SC, independently accounting for 0.8-1.5% of the total SC variation. Analyses using the generalized linear mixed models (GLMMs) showed that habitat diversity was the most important determinant of bryophyte SR, followed by elevation, area, isolation degree, vegetation coverage, and shape irregularity. All six patch attributes exerted positive effects on SR except isolation degree. Area, elevation, and shape had a positive interaction effect on bryophyte SR. Our results imply that a subtropical forest reserve for bryophyte conservation had better be designated to have high habitat diversity, a large area, a large elevation range, and irregularly-shaped fragments adjacent in distance. [ABSTRACT FROM AUTHOR]

Macromitrium tosae Besch. and M. cavaleriei Cardot & Thér. are two taxa that are poorly discriminated from one another, and M. melanostomum Paris & Broth., M. courtoisii Broth. & Paris, M. cylindrothecium Nog. and M. chungkingense P. C. Chen are four little known species. Cluster and Principle Component Analyses were applied to evaluate the morphological distinctiveness of these species based on 27 character indices of leaf morphology from ten type specimens and 17 other specimens. Macromitrium cylindrothecium, M. chungkingense, M. courtoisi and M. melanostomum are not unambiguously distinct from M. tosae and should therefore be considered conspecific. Macromitrium tosae, a common species in China, differs, however, from M. cavaleriei by shorter, lingulate, apiculate branch leaves with obtuse apices and distinctly Pluri--papillose laminal cells, and its inner perichaetial leaves with acuminate or short acuminate apices. [ABSTRACT FROM AUTHOR]

Ptychomitrium tortula (Harv.) A.Jaeger, P. lepidomitrium (C.Muell) Schimp., P. rhacomitrioides Dixon and P. lindigii (Hampe) Jaeg. are similar in morphology by having scabrous calyptrae, sinuous basal leaf cells and crisped and contorted dry leaves. Studies of the type specimens of these species indicated that P. rhacomitrioides and P. lindigii are synonymous with P. tortula and P. lepidomitrium, respectively. Comparisons of the morphological features and distribution in detail showed that P. tortula and P. lepidomitrium are two distinctive species with geographical disjunction between Asia and Central and South America. [ABSTRACT FROM AUTHOR]

When measuring photosynthesis in mosses, the non-photosynthetic (brown) sections are usually removed and only the green sections are measured. However, how this pretreatment affects photosynthesis rates is unclear. Therefore, we studied the effect of removing the non-photosynthetic sections in three moss species with distinct morphological and stem-anatomical structures, comparing net CO2 assimilation rates (AN) of detached green and brown sections to those of intact shoots. Right after separation, the summed AN of the separated sections was significantly lower than those of the intact shoots for Pogonatum nudiusculum Mitt. and Pleuroziopsis ruthenica (Weinm.) Kindb. ex E. Britton, while no significant difference was found for Actinothuidium hookeri (Mitt.) Broth. However, AN recovered within a day, and the progressive reduction of AN expected if carbonsink removal was an important mechanism was not observed. Our study indicates that removal of non-photosynthetic sections results in an underestimation of the photosynthetic capacity of the green moss sections, but only for the species with relatively complex internal transport structures, and only immediately after the separation. The fast and transient response suggests a mechanism via an electrical signal induced by wounding or reduced hydraulic integrity, rather than through a reduced carbon-sink strength. More comprehensive investigations on signaling and other mechanisms regulating moss photosynthesis will contribute to more accurate measurement methods as well as a deeper understanding of moss ecophysiology and the contribution of mosses to carbon fluxes in terrestrial ecosystems. [ABSTRACT FROM AUTHOR]