Background & Summary

Climate change exerts extensive effects on both biodiversity and the functioning of mountain ecosystems, influencing not just the distribution of species1,2 but also their phenological patterns3,4. As traits may be influenced by environmental factors, evolutionary background, and plasticity5,6, employing trait-based methods provides significant opportunities to enhance our understanding of the drivers, limitations, and repercussions of variability in biodiversity and ecosystem responses to climate change. Given that functional traits are effective tools to document the differences among individuals regarding their capabilities to thrive, reproduce, and perform in diverse environmental contexts, these traits can deepen our mechanistic insights into how species respond to and function amidst climate change, thereby establishing a connection between individual phenotypes and their surrounding environment7.

Mountains display significant differences in biodiversity along elevational gradients, largely attributable to their complex topographical features, climatic conditions, and geological past. By examining elevational gradients, researchers can deduce the climatic niches of various species and their potential distribution boundaries, which is particularly critical for understanding biological responses to climate change8,9. For example, an increase in temperature might trigger shifts in species ranges or elevate extinction risks for specialists thriving at high elevations10. These trends underscore the importance of studying elevation in forecasting changes in distributions and providing crucial insights for biodiversity conservation during the Anthropocene.

China stands out as one of the most biodiverse countries globally, especially within its vast subtropical zone. Covering more than 10 degrees of latitude across an area of 2.5 million km², this region harbors one of the world’s most extensive areas of evergreen broad-leaved forests, renowned for their unparalleled species richness and evolutionary significance11. This region contains vegetation types primarily established during the Tertiary period, along with a considerable number of relatively ancient genera and species12. Research has shown that the subtropical region of China acts as both a “museum” and a “cradle” for the emergence of woody plant diversity13. Within this subtropical area, the mountainous regions of Eastern China harbor an exceptionally high and unique diversity of species, resulting from the intricate interactions between mountain ranges, river systems, and climatic factors. These regions, which have served as significant refuges for paleovegetation and biota since both Tertiary and Quaternary eras, host many relict species dating back to the Tertiary, making them critical for biodiversity conservation efforts in China14,15. Nonetheless, this region is also one of the fastest-developing regions in China regarding economic growth and tourism, leading to increasing anthropogenic pressures that demand stricter biodiversity conservation measures.

Bryophytes, which include liverworts, mosses, and hornworts, consist of approximately 16,000 species, making them the second largest group of living terrestrial plants, only after angiosperms16. They play crucial roles in various ecosystem functions, such as improving the physical properties of soil17, facilitating nutrient biogeochemical cycling18, and retaining water19. Even though they are ecologically significant, bryophytes are infrequently taken into account in biodiversity assessments when compared to vascular plants20. On a global scale, the presence of a consistent latitudinal species richness gradient has sparked controversy for a long time, mainly due to the absence of an up-to-date synthesis of global species distribution patterns21.

In order to assess the effects of climate change on mountain biodiversity, a long-term initiative called BEST (Biodiversity along Elevational Gradients: Shifts and Transitions) Network (https://BEST-mountains.org) was launched in 2017. This project, which encompasses collaboration among over 20 research teams, led to the establishment of more than 300 permanent plots at various elevations across a total of 18 mountains located between 19.07°N and 43.37°N, ranging from 166 m to 3,835 m.

Utilizing the BEST Network, we are undertaking long-term observations to examine the alterations in the geographic distribution and abundance of bryophytes in response to climate changes. This paper presents a comprehensive dataset of bryophyte diversity and traits, which is collected from elevational gradients in four subtropical mountain ecosystems located in Eastern China. To compile a thorough inventory of bryophytes, we implemented both plot sampling (PS) and floristic habitat sampling (FHS) as described by Ilić et al.22. The plant traits of bryophyte communities were primarily gathered from the taxonomic revisions and regional bryofloras.

The dataset contains information on bryophyte species in four nature reserves in Eastern China within the range from 114.29°E–119.27°E and from 25.38°N–31.20°N (Fig. 1; Table 1), comprising Anhui Province, Zhejiang Province, Jiangxi Province and Fujian Province. The resulting dataset contains 549 bryophytes belonging to 195 genera, 71 families, accounting for 16% of Chinese bryophyte diversity. The dataset includes 16,920 trait measurements across 549 taxa, marking the first regional-scale bryophyte trait dataset for China. This dataset is released for noncommercial use only and is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). All publications that use this dataset should appropriately cite the dataset and this paper.

Fig. 1
figure 1

Distribution map of bryophyte sampling plots in Eastern China. (a) Mt. Dabie (b) Mt. Daiyun (c) Mt. Guan (d) Mt. Tianmu.

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Table 1 Overview of sampling sites included in the bryophyte species-trait dataset.
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The dataset can be utilized to: (i) identify regional hotspots of bryophyte diversity to inform the delineation of priority conservation areas; (ii) assess how species are distributed from regional species pools to local communities and evaluate the factors influencing this distribution; (iii) evaluate the endemism and conservation status of species at a regional scale; and (iv) serve as a fundamental baseline for assessing how bryophyte diversity and its elevational distribution respond to climate change and anthropogenic disturbances.

In conclusion, this dataset represents a significant regional dataset on elevational gradients of bryophyte species richness sourced from field investigations. The continuous monitoring project, which focuses on changes in the richness and distribution of bryophytes along various elevational and latitudinal gradients, will enhance our understanding of how climate-related factors affect the shifting ranges of these organisms over time.

Methods

Research site selection

The establishment of field plots and associated surveys for this study were carried out under the framework of the BEST Network. This network represents a long-term monitoring initiative aimed at investigating the dynamics of multi-taxa biodiversity in the context of climate change and land-use impacts in China. Through the BEST Network, permanent biodiversity monitoring plots have been established across 18 mountains situated in the tropical and subtropical regions of China. These plots are critical for conducting comprehensive surveys across various taxa, including plants, birds, insects, and soil fauna. The overarching aim of these efforts is to elucidate biodiversity patterns and identify the drivers behind their distribution with respect to elevation (as referenced on the BEST Network website: https://BEST-mountains.org).

In this study, we selected 67 permanent plots across four subtropical mountain ecosystems: Mt. Dabie in Anhui, Mt. Tianmu in Zhejiang, Mt. Guan in Jiangxi, and Mt. Daiyun in Fujian, spanning an elevation range from 281 m to 1,600 m (Fig. 1). Through a combination of field reconnaissance, expertise from local scholars, and remote sensing information, we chose sites characterized by representative zonal vegetation, minimal human disturbance, and uninterrupted elevational gradients. Employing a closed traverse approach, areas of plantations or secondary growth were intentionally excluded, plots measuring 20 m × 20 m or 20 m × 30 m were set up in mature forest zones, ensuring roughly 100 m elevation intervals between adjacent plots. To ensure a consistent approach in our research, we have decided to use a uniform plot size of 20 m × 20 m when examining the diversity of bryophytes. This standardized measurement allows for a systematic comparison across different sampling sites and facilitates the collection of reliable data on bryophyte populations. In light of the complexity of the terrain and the structure of the forests, 1-2 parallel plots were flexibly established at each elevation. A particularly noteworthy aspect of our study can be found in Mt. Tianmu, where 37 plots were set up along the elevational gradient. This particular arrangement was intended to investigate the effects of sampling effort on species diversity, thereby contributing to a deeper understanding of biodiversity in relation to elevational fluctuations.

Sampling strategy

All bryophyte species in each plot were surveyed between April 2018 and August 2022. To obtain data on species richness in a plot as complete as possible, both plot sampling (PS) and floristic habitat sampling (FHS) methods22 were used in the field work (Fig. 2). For detailed methodology regarding the sampling methods and strategies employed in this study, please refer to Dai et al.23.

Fig. 2
figure 2

Schematic diagram of sampling methodology (adjusted to cite Wang et al.71).

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It is widely recognized that each sampling method has its unique strengths and weaknesses24. The PS method is particularly adept at identifying common species and evaluating their distribution and frequency; however, it often overlooks rare species25. Conversely, the FHS method uses the entire mesohabitat as its fundamental sampling unit, providing the flexibility to consider the variability of microhabitats within a mesohabitat, which notably enhances the chance of discovering rare species26. In this study, while the FHS method recorded a higher average species richness per plot when compared to the PS method, the PS method proved effective in detecting smaller bryophyte species, especially those in the Lejeuneaceae family. In fact, employing a combined strategy utilizing both sampling methods has shown to be advantageous in increasing species discoveries. In contrast, had we depended solely on the FHS method or the PS method, we would have missed approximately 26% to 29% of newly documented species27.

Species identification and taxonomic standardization

The specimens that were gathered have been deposited in the Biological History Museum East China Normal University (HSNU). Both morphological and anatomical examinations were carried out utilizing an Olympus SZX7 stereomicroscope in conjunction with an Olympus BX43 light microscope. A variety of publications and literature relating to the taxonomy and flora of Chinese bryophytes28,29,30,31 served as references for specimen identification. For those specimens that posed taxonomic challenges, expertise was sought from specialists across various taxonomic groups within China, ensuring that all identifications were made with a high degree of accuracy and reliability.

Dataset collection methods

Taxonomy

The standardization of species names is primarily based on The Bryophyte Nomenclator (https://www.bryonames.org/), while the Catalogue of Life China (http://sp2000.org.cn/) is also used as supplementary references. This multi-source approach enables robust validation of nomenclature and taxonomy. Additionally, for species with disputed taxonomic status, several specialized taxonomic monographs and dissertations have been referenced to ensure the reliability of the species list (e.g., Zhao & Liu32, Wang & Jia33 and Wang et al.34).

Distribution

The latitude, longitude, and elevation information for all sampling plots were obtained from the BEST Network. During the field investigation, the rough taxonomic classification corresponding to each specimen, as well as the host plant code number, and substrate type were recorded.

Functional traits

The extraction of bryophyte functional traits followed a sequential workflow (Fig. 3): Initially, primary reliance was placed on taxonomic revisions, such as A Taxonomic Study of the Family Bryaceae (Sensu Lato, Bryopsida) in China32, A Monograph of the Genus Ulota s.l. (Orthotrichaceae, Moss)33 and Taxonomic revision of Lejeuneaceae subfamily Ptychanthoideae (Marchantiophyta) in China34. For taxa that have not been revised, Flora Bryophytorum Sinicorum35,36,37,38,39,40,41,42,43,44 served as the core reference, supplemented by regional bryofloras, including Flora Yunnanica (Tomus 17) Bryophyta: Hepaticae, Anthocerotae28 and Bryophytes of Yachang-Liverworts and Hornworts45. Subsequently, traits that remained unresolved were extracted from the Bryophytes of Europe Traits (BET) dataset46. Persisting data gaps for some species were addressed by inferring phylogenetically conserved traits—including growth form, sex and spore surface ornamentation—from higher taxonomic ranks (family or genus), utilizing the Guide to the Bryophytes of Tropical America47 and related taxonomic treatments. In the case of some highly diverse families (such as Brachytheciaceae and Pottiaceae), the forementioned trait information may still exhibit instability at the family or genus level; therefore, these data are treated as missing values.

Fig. 3
figure 3

Overview of the workflow for generating the bryophyte species-trait dataset.

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Data Records

The dataset is available from Figshare repository48 (https://doi.org/10.6084/m9.figshare.29826515.v5). Data from 8,112 specimens across four sampling sites were organized into four categories: taxonomy, distribution, resistance traits, and reproductive traits (Table 2). The taxonomic information in the bryophyte species-trait dataset includes species name, order, family and genus, revealing 549 bryophyte species in Eastern China, distributed across 21 orders, 71 families, and 195 genera. Among these, there are 158 liverworts, classified into 7 orders, 24 families, and 42 genera. Additionally, there are 391 mosses categorized into 14 orders, 47 families, and 153 genera.

Table 2 Dataset fields included in bryophyte species-trait dataset, grouped across four categories: taxonomy, distribution, resistance traits, and reproductive traits.
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The distribution information in the bryophyte species-trait dataset encompasses geographical distribution, elevational distribution and substrate. Geographical distribution data document the presence/absence of bryophytes across four sampling sites. Elevational distribution data, which cover an elevation gradient from 281 m to 1,600 m, were compiled by segmenting the range into 200 m elevation intervals and recording species occurrences within each elevational band. Substrate data indicate the presence/absence of bryophytes across various substrate types.

The functional traits of the dataset can be classified into two categories: resistance traits and reproductive traits. Notably, bryophytes are poikilohydric plants, which makes them particularly sensitive to variations in environmental moisture. Consequently, their resistance traits are predominantly associated with water. In this study, we selected and extracted five water-related resistance traits: growth form, leaf ornamentation, midrib extension, stem paraphyllia/pseudo-paraphyllia and hyaline hair point/hyaline margin, primarily for the following reasons: (i) the various growth forms exhibited by bryophyte gametophytes indicate different approaches to water conduction, retention, and gas exchange, which are vital for photosynthesis49. Leafy liverworts and pleurocarpous mosses thrive in humid and shaded locations, whereas thallus liverworts and acrocarpous mosses have evolved distinct mechanisms for enduring drought conditions50; (ii) leaf ornamentation is essential for the processes of water absorption and transportation. In leaves that are papillose or mammillose, tiny protrusions on the cell surfaces enhance water uptake by forming capillary channels and facilitate water movement, functioning like capillaries without hindering gaseous exchanges, thus promoting the rewetting of leaves more effectively51,52,53; (iii) midrib of a leaf can either extend throughout the entire length of the leaf, which is referred to as a percurrent midrib, or surpass it, known as an excurrent midrib, which plays a crucial role in providing structural support, particularly during periods of desiccation. Research has also shown that this structural feature can facilitates water transport within the plant51,52,54; (iv) stem paraphyllia or pseudoparaphyllia are reduced leaflike appendages on the stem or branch of some mosses, which is also associated with environmental water utilization, interception, and retention55; and (v) hyaline hair point refers to the transparent, often shiny apex found at the end of an elongated leaf blade. Species possessing hyaline hair points can reduce water loss by adjusting the orientation of their hair point during dry conditions49,56. Furthermore, a hyaline hair point aids in minimizing water loss also by shielding leaves from solar radiation49,57,58,59 and capturing dew49,51,60.

Reproductive traits play a crucial role in the establishment and maintenance of bryophyte communities. Sierra et al.61 utilized reproductive traits as indicators to predict the formation time of epiphyllous liverwort communities. In our study, we selected seven reproductive traits: vegetative reproduction, sex, maximum seta length, peristome, minimum spore size, maximum spore size, and spore ornamentation. We hypothesize that bryophytes possessing vegetative reproduction, elongated setae, small and mammillose/papillose spores, as well as distinctly peristome structures, are more conducive to dispersal and propagation29,50,62.

Data Overview

Families and genera with a number of species greater than or equal to 5 are defined as dominant families and dominant genera, while those with fewer than 5 species are combined into “Others” (Fig. 4). There are 30 dominant bryophyte families and 25 dominant genera in Eastern China. The most diverse families in bryophyte species-trait dataset are Hypnaceae (50 species, 9.11%) and Lejeuneaceae (42 species, 7.65%), followed by Brachytheciaceae (34 species, 6.19%), Dicranaceae (31 species, 5.65%), and Thuidiaceae (28 species, 5.10%). At the genus level, Frullania (21 species, 3.83%), Porella (20 species, 3.64%), Entodon (19 species, 3.46%) and Fissidens (17 species, 3.10%) emerge as the most speciose genera, followed by Brachythecium and Plagiothecium (13 species each, 2.36%), Plagiomnium (12 species, 2.19%).

Fig. 4
figure 4

Pie chart of the proportions of dominant bryophyte families (left) and genera (right), with the size of each pie proportional to the number of species relative to the total species inhabiting Eastern China.

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Based on a comparative analysis of bryophyte diversity across four sampling sites, Mt. Tianmu exhibits the highest species richness with 387 documented bryophyte species, while Mt. Daiyun displays the lowest species richness, with 107 recorded bryophyte species (Fig. 5).

Fig. 5
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Species richness of liverworts and mosses across four sampling sites.

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Across all substrate types, arboreal substrates, including tree bases and tree trunks, supported the highest bryophyte species richness, with 341 species (62.11%) and 326 species (59.38% of total regional bryophytes) respectively. This was followed by rock covered with a thin layer of soil, (174 species, 31.69%), decaying wood (171 species, 31.15%), rock surfaces (152 species, 27.69%), and soil (98 species, 17.85%). In sharp contrast, branch-dwelling and epiphyllous habitats exhibited minimal species representation, with only 54 species (9.84%) and 14 species (2.55%), respectively (Fig. 6).

Fig. 6
figure 6

Species richness of different growth forms of bryophytes across various substrates.

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Bryophytes of various growth forms exhibited distinct substrate preferences (Fig. 6). Acrocarpous mosses were relatively uniformly distributed across all habitats, with the exception of branch-dwelling and epiphyllous substrates. In contrast, pleurocarpous mosses and leafy liverworts demonstrated a pronounced preference for arboreal habitats, including tree trunks and tree bases. Thallus liverworts maintained broad distribution patterns, being absent only from epiphyllous habitats while occurring uniformly across other substrates.

Technical Validation

In order to evaluate how sampling effort influences bryophyte species richness, we purposefully selected 12 plots from a total of 37 located in Mt. Tianmu during the summer of 2020. These plots were strategically chosen at intervals of 100 m in elevation. Within each sampling plot, we randomly selected 10 trees that possessed a diameter at breast height (DBH) greater than 15 cm. The surveys conducted aimed to assess bryophyte diversity by examining subplots at four different heights (0.3 m, 1.1 m, 1.5 m, and 1.8 m above the ground) on both the northern and southern sides of each tree. The findings indicated that sampling exclusively at heights of 0.3 m and 1.5 m (which involved two subplots per tree) accounted for 75% of the overall species diversity found when sampling all four heights and aspects (eight subplots per tree)63. This indicates that concentrating sampling efforts at the 0.3 m and 1.5 m heights can yield substantial coverage of species diversity, particularly in situations where time and resources may be constrained.

In order to ensure a thorough and systematic approach to sampling both liverworts and mosses, all field collections were conducted collaboratively by experts who specialize in each respective group. The specimens that were collected were then identified by leading domestic experts in the fields of liverwort and moss identification. To aid in the identification of particularly challenging specimens, molecular phylogenetic techniques were employed. Additionally, to uphold consistency throughout the sampling and identification processes, the same team members were responsible for both the fieldwork and the laboratory identification of the specimens. This approach not only promoted uniformity in methodology but also enhanced the reliability of the findings.

Usage Notes

This study established a bryophyte species-trait dataset to ensure data accessibility and interdisciplinary integration. For data collection, the research team conducted PS surveys at 0.3 m, 1.1 m, 1.5 m, and 1.8 m heights along north-south transects in 12 of 37 permanent plots in Mt. Tianmu, thereby developing a standardized protocol for bryophyte surveys in Eastern China63. It should be noted that methodological inconsistencies in sampling may introduce observational biases in regional biodiversity assessments. Furthermore, bryophytes’ high climatic sensitivity drives their elevational/latitudinal range shifts in response to global warming. Our four-year investigation on bryophyte diversity in Eastern China lead to the following conclusions: sampling time differences may affect the comparison of diversity among different sites; the extension of the study period may exacerbate the differences in diversity and species composition among sites; and interannual variations in wet and dry seasons may drive dynamic changes in species composition.

Furthermore, it is important to emphasize that, consistent with other bryophyte databases such as BET46, BRYOATT64 and BryForTrait65, the dataset used in this study mainly depends on previously published literature and existing datasets, instead of being gathered from direct measurements taken in the field for trait values. While this approach is valid, data from these sources generally leans more towards qualitative aspects than quantitative ones. Additionally, this method of directly extracting trait data from literature frequently fails to account for intraspecific variation. Comparisons of functional traits among species often presume that trait variation within a species is minimal. Nevertheless, intraspecific trait variation is recognized to account for a significant portion of functional trait variation within communities66,67 and can even exceed interspecific trait variation along comparable environmental gradients68. Considering that intraspecific variation might be crucial for the survival of bryophytes in the face of climate change69,70, it is essential to prioritize the understanding of which functional traits exhibit plasticity and to identify any potential trade-offs associated with high levels of plasticity. Therefore, it is recommended that subsequent studies, when using this data for diversity pattern comparisons or analyzing community assembly processes from regional to local scales, should fully consider these limiting factors.