Located in the northeast of the Qinzang Plateau, Qaidam Basin is a huge plateau-type closed basin. The vegetation is dominated by desert, including swamp wetlands, halophytic meadows and montane grasslands. In order to show the species composition, community characteristics and distribution pattern of vegetation in Qaidam Basin in more detail, this paper uses the field data of the Second Tibetan Plateau Scientific Expedition and Reserch of 2022 and the Comprehensive Scientific Investigation of the Data-scarce Area of the Qinghai-Tibet Plateau of 2014, including 157 sample plots and 458 sample plots, which are integrated into the sample data set of plant communities in Qaidam Basin. Through the collation and compilation of data, a total of 185 species information was obtained, among which the families with the largest number of species were Asteraceae (39 species), Poaceae (33 species), Fabaceae (17 species), Amaranthaceae (16 species) and Brassicaceae (10 species) , and the genera with the largest number of species were Stipa, Artemisia, Astragalus, Oxytropis and Saussurea. The composition of plant life form is dominated by herbs, accounting for 78.37%. The species of middle Asia account for 41.62% of the geographical composition of the flora. Based on the phytocoenological-ecological principles, 163 sample plots can be classified into 4 vegetation formation groups, 7 vegetation formations, 11 vegetation subformations and 40 alliances. This data set can provide the most original basic data for the in-depth study of vegetation characteristics in Qaidam basin, the compilation and research of the Vegegraphy of China, and the mapping of Qingzang Plateau and the national vegetation map.

The valley forest in the Ertix River basin is the germplasm bank of Salicaceae species and has important genetic diversity value of Altay Prefecture, Xinjiang Uygur Autonomous Region. It is of great significance for the protection and utilization of precious resources to study the distribution of plant species and vegetation types under the current human activities such as climate change, hydropower project and grazing. In this paper, 80 squares of 20 plots were investigated at 4–8 km intervals in the Burqin River, Haba River and Bilizik River, the constructive species, quantitative characteristics and diameter class structure of the community were analyzed, and the community types were classified. The results showed that, (1) 121 species, 34 families and 91 genera of plants were investigated in the main tributaries of the Irtysh River basin, with a large number of perennial herbaceous plants. (2) Betula pendula and Populus laurifolia were constructive species in Burjin River and Haba River, while Populus alba was constructive species in Bilizik River. Populus nigra, Populus × berolinensis var. jrtyschensis, and Populus canescens are associated species, while Salix alba is mainly distributed alone along the riparian edge and rarely mixed with poplar species. (3) The number of individuals of the dominant tree species Betula pendula reached the maximum at the middle elevation of the three tributaries, while the number of individuals of Populus laurifolia was smaller at the middle elevation. (4) The diameter class structure of tree layer species was greatly affected by grazing in summer, and the individuals of large diameter class were the most, and the number of saplings and seedlings were less. (5) The valley forest communities were divided into 6 formations and 26 associations.

Dongtou National Marine Park (DNMP) locates at the southeast coast of China, and the climax vegetation belongs to the subtropical evergreen broadleaf forests. However, we are still unclear about the vegetation types on most islands in DNMP. The objective of this study is to investigate vegetation types and characteristics across islands in DNMP. We conducted vegetation survey by setting up 90 sampling plots on the islands in DNMP. Species composition and habitat information in each plot were recorded and vegetation type classification and naming were referred according to the Vegegraphy of China. A total of 3 Vegetation Formation Groups, 8 Vegetation Formations, 34 Alliances, and 80 Associations were found in DNMP. The widely distributed vegetation types included Pinus thunbergii evergreen needleleaf forest, Casuarina equisetifolia evergreen broadleaf forest, Acacia confuse evergreen broadleaf forest, Eurya emarginata evergreen broadleaf shrubland, and Eurya japonica evergreen broadleaf shrubland. Our finding provides basic and detail information of vegetation structure and composition in these continental islands in eastern China.

Nine uninhabited islands with different sizes, laying on the coast of Bohai Sea, were selected as research objects for a further understanding and study of the characteristics of plant communities. By using the method of sample plot survey, we investigated a total of 66 sample plots, covering the study of species composition, and the number of individuals, height and diameter at breast height (DBH) of woody plants, etc. 140 species of vascular plants belonging to 38 families and 98 genera were investigated through sampling plot method. The results showed that Asteraceae, Poaceae, Fabaceae were the most abundant families in the communities. Moreover, the native forest vegetation has been replaced by secondary ones dominated by Robinia pseudoacacia, Pinus thunbergii, Ailanthus altissima, and Ulmus macrocarpa, respectively. Meanwhile, temperate deciduous shrubland became zonal vegetation type in this area, and the representative communities are dominated by Ziziphus jujuba var. spinosa, Periploca sepium, Flueggea suffruticosa, Celastrus orbiculatus, respectively. And representative herbaceous alliances are dominated by Artemisia argyi, Suaeda salsa, A. capillaris, and Themeda triandra, respectively. In general, the species diversity of island plant communities is relatively low, belonging to vulnerable vegetation.

Aims Analyzing characteristics of the population and community is one of the most effective approaches to determining their endangered status. Listed as second-level endangered species, Acer miaotaiense was regarded as an extremely small population species. However, as details on the distribution and population characteristics of the species are lacking in Shennongjia area, the conservation of this species is severely constrained.

Methods This study investigated population and community characteristics of A. miaotaiense in Shennongjia area. We studied the population dynamics of the species by analyzing its age structure, static life table, and survival curve.

Important findings The results showed that: (1) there were 33 species of woody plants belonging to 15 families and 20 genera in the community, and the dominant species in the community were Juglans mandshurica, Carpinus cordata, Dipteronia sinensis and Corylus chinensis. (2) The relative importance value of A. miaotaiense was 2.23%, making it a non-dominant species in the community. (3) The distribution range of A. miaotaiense in Shennongjia was very narrow (about 1.7 hm²), and the population size was small (79 plants). (4) The proportion of young individuals of A. miaotaiense was relatively high (79.75%), indicating good regeneration. (5) The species survival curve belonged to the Deevey-II type, and the mortality rate of each age group of the population was similar. However, the mortality rate increased in the juvenile stage and peaked (62.5%) in the adult stage (12.5 cm ≤ diameter at breast height < 17.5 cm). (6) Fruiting individuals were rare, and a high percentage of seeds (58.15%) was non-viable, and resistance to external disturbance was low. In summary, the small population size, narrow distribution range, and low resistance to external disturbance are the likely factors contributing to the endangered status of A. miaotaiense in Shennongjia area. We believe that the population of A. miaotaiense in Shennongjia area is declining. Therefore, it is necessary to strengthen in situ conservation of the existing A. miaotaiense population, especially the young trees in the Shennongjia area. In the future, programs should be set up to monitor the population dynamics of the species and carry out seedling breeding for population restoration of the species.

Aims Seedlings play a crucial role in the conservation of forest biodiversity. Previous studies have paid little attention to seedling communities in monsoon broadleaf evergreen forests in Pu’er, Yunnan. Our aim was to investigate the mechanisms of seedling community assembly there.

Methods We analyzed the species composition of the seedling community based on the seedling survey in a 30 hm² forest dynamics plot. Seedling plots are divided into different groups according to the dominant species. The stepwise community assembly model (STEPCAM) was used to investigate the mechanisms of community assembly and to further analyze the functional traits of seedling communities.

Castanopsis echidnocarpa and C. calathiformis are the dominant seedling species in the monsoon broadleaf evergreen forest. Four plot types (i.e., C. echidnocarpa plot, C. calathiformis plot, mixed-dominant species plot, non-dominant species plot) were classified according to the presence or absence of dominant species. The seedling community assembly processes included: a) random dispersal assembly (with contribution rate 43.1%-61.3%); b) habitat filtering (with contribution rate 27.4%-33.9%); and c) limiting similarity (with contribution rate 5.7%-27.2%). The C. echidnocarpa and C. calathiformis plots were dominated by deterministic processes, with 56.9% and 54.6% contributions respectively, whereas the mixed-dominant and non-dominant species plots were dominated by stochastic processes, with 60.4% and 61.3% contributions respectively. Rao’s quadratic entropy (Rao’Q) was highest in the non-dominant species plot and lowest in the mixed-dominant species plot. The C. echidnocarpa plot has the lowest specific leaf area (SLA) and higher leaf thickness (LT), specific stem length (SSL), root mass fraction (RMF) and a maximum potential plant height (PPH), while the C. calathiformis plot and non-dominant species plot have a higher SLA. Among different seedling plots, the coefficients of variation for SSL and PPH were higher, while the coefficients of variation for other functional traits were lower. Multiple regression analysis showed that SLA and PPH were significantly and positively correlated with Rao’Q in different seedling plots. LT and life form were significantly and positively correlated with Rao’Q in other three types of plots, except for the non-dominant species plot. Thus, seedling community assembly in the monsoon broadleaf evergreen forest is driven by both stochastic and deterministic processes, and the contribution of the two processes varies with the type of seedling communities.

Aims Grazing, one of the primary ways of grassland utilization in Nei Mongol, has essential influences on plant community properties of grasslands. However, the comprehensive response patterns of Nei Mongol grassland plant community properties to grazing remain unclear.
Methods Based on a dataset derived from 76 studies, the plant community characteristics and soil physicochemical properties of Nei Mongol grasslands under different grazing intensities, different grassland types and different grazing years were integrated and analyzed in order to comprehensively evaluate the response patterns of Nei Mongol grasslands to grazing.
Important findings Our results showed that grazing significantly reduced plant above/below ground biomass, cover, height, density, species richness, Shannon-Wiener diversity index, Pielou evenness index, Simpson diversity index, and soil water content. The negative effects of grazing were strengthened with increasing of grazing intensity and duration. Moreover, grazing had a greater negative effect on the grasslands with sparse vegetation and low environmental carrying capacity (e.g., desert grasslands, sandy areas, etc.). This study shows that the responses of plant community characteristics to grazing in Nei Mongol grasslands are regulated by multiple factors, and appropriate grazing intensity and grazing time should be set according to different types of grasslands to achieve sustainable utilization of grasslands. The standards of grazing intensity in current grazing studies are not uniform, making it difficult to compare different studies, and the results from some studies do not have statistical significance due to a lack of replications in the experiment. The exploration of uniform quantitative standards for grazing intensity will be an important and challenging issue in future grazing studies, and the rationality of experimental design should also be emphasized.

Caryopteris mongholica is a key protected wildflower plant distributed in typical steppe, desertified steppe and desert areas. But there is a lack of research on its community characteristics and classification. This paper aims to study the distribution, characteristics and classification of C. mongholica in northern China and provide a reference for further protection and management. From 2018 to 2021, a total of 40 representative C. mongholica sites were selected in northern China, and their community characteristics were studied using the sample plot survey method. Results showed: (1) Caryopteris mongholica is concentrated in the eastern, central and western of Nei Mongol Plateau, the northern Loess Plateau, Hexi Corridor, Qilian Mountains and other northwest temperate desert or steppe areas in China, and is often the dominant or associated species in the communities. (2) According to the survey of 40 sample sites, a total of 149 species of seed plants were recorded, belonging to 107 genera of 37 families, among which 31 communities with C. mongholica as construction or dominant species and 140 species of seed plants were recorded, mainly Compositae, Leguminosae and Gramineae. Among them, 39 species were shrubs, dwarf- and semi-shrubs, 76 species were perennial herbs and 24 species were annuals and biennials. In the classification of species presence, 87.94% were occasional species with frequency distribution less than 20%. Wide-range xerophytes occupied the advantage (63.12%) in the water ecological types. Middle Asia elements (26.24%) were the major floristic geographic elements. (3) Based on the life form and dominance of species, the 31 C. mongholica communities were divided into 3 association groups, C. mongholica - herb association group, C. mongholica + shrub - herb association group and C. mongholica + shrub association group, which were further subdivided into 19 associations. (4) Longitude and annual precipitation significantly influence the distribution of C. mongholica communities and species diversity.

Tropical rain forests are currently distributed in the southeastern Xizang, southern Yunnan, southern Guangxi, southern Taiwan, and Hainan Island in China. The ecological physiognomy, species composition and diversity of the tropical rain forests were reported in literatures, however with different terms for different regions of China, due partly to different methods, definitions and references used. In this review article, we summarize current research status and main questions on the phytosociological characteristics of the tropical rain forests in China, to provide information for further studies, protection and management. The lowland tropical rain forests in China belong to the northern marginal type of the southeastern Asian lowland rain forests, and share the similar community structure, physiognomy, and species diversity with other subtypes of the southeastern Asian lowland rain forests. Distributed in the northern edge of the monsoonal tropical zone, the lowland tropical rain forests in China are limited by seasonal drought and insufficient amount of heat, which is usually demanded by typical tropical rain forests, and therefore were given the name “tropical seasonal rain forest” by Chinese researchers. They are different from the typical humid or wet tropical rain forests in that they include a certain proportion of deciduous trees in canopy, less megaphanerophytes and epiphytes, but more lianas and microphyllous species in tree leaf sizes. The tropical rain forests in China show different floristic composition in different regions. Specifically, they contain less typical tropical floristic components, and show a transition to the tropical lower montane forests in southwestern China, and to the subtropical evergreen broad-leaved forests in south China. They show similar community structure and ecological physiognomy in Yunnan and Guangxi. Furthermore, the tropical seasonal rain forest in Yunnan contains dipterocarp trees and has the highest proportion of tropical Asian floristic components among the tropical rain forests in China and show the similar community structure characteristics as the lowland tropical rain forests in the Southeast Asia, although occurring on a higher altitude (up to 1 100 m above sea level, can reach up to 1 300 m in some certain areas). We further discuss the uncertainty and confusion in definition, classification and description of the tropical rain forests from literatures in different regions of China and propose to give a consolidated consideration on the definition and classification of the tropical rain forests in China.

Aims In studies on the relationship between plant species richness and productivity, species richness is regarded primarily as an independent variable and productivity as a response variable, whereas other factors that may affect community productivity at the same species richness levels, such as species combination and composition, are largely ignored. The objectives of this research have been determined: (1) the effect of community structure on community productivity, including species combination, composition, and functional groups to which the species belongs, and (2) the relationship between species richness and community productivity in subalpine meadow communities.
Methods In the pot experiment, seeds of four plant species (Festuca sinensis, Elymus nutans, Medicago sativa and Dactylis glomerata) were sown to pots in terms of given species combination and composition at varying levels of species richness (1, 2, 3, 4). In both monocultures and mixtures, the overall planting density of the community was 100. Seeds were sown in equal numbers to pots in communities of diverse species combinations at various levels of species richness. The species composition of four-species mixed-seeding communities was designed as 10%, 20%, 30%, and 40% density proportions, respectively. Each treatment had five replicates, and weeds were manually removed on a regular basis. The above-ground biomass in each pot had been harvested, dried, and measured by species at the end of September.
Important findings Community productivity increased with increasing species richness at lower species richness, but not substantially at higher species richness, The combination and composition of community species had a significant effect on community productivity, with the mixed-seeding community containing Elymus nutans and communities with a high proportion of Elymus nutans having higher productivity. Among the functional groups to which the species belonged, legumes either promoted or inhibited the production of other species. Elymus nutans enhanced community productivity, whereas Festuca sinensis and Dactylis glomerata had no discernible effect. As a result, it could be inferred that there is an apparent relationship between species richness and productivity, and plant community productivity is more dependent on species combination and composition than on species richness.

Aims Environmental factors are among the key factors governing the community species spatial turnover. As one of the widely distributed vegetation types in subtropical region of China, it is important to understand the species composition differences among shrubland communities, which will provide important information for protecting biodiversity and eco-security shield construction in the northern mid-subtropical region, China. However, little is known about which factors drive the species spatial turnover in subtropical region of China. The objectives of this study were to investigate the shrubland community spatial turnover pattern and to determine the key factors that shape the present distribution of species based on the field-based data in northern mid-subtropical China.
Methods Based on the field-based data in mid-subtropical shrublands, we used the generalized dissimilarity modelling (GDM) by the Bray-Curtis dissimilarity index to explore the driving effects of climate, soil, topography, and human disturbance on species turnover of the shrubland communities in northern mid-subtropical China.
Important findings The results showed that climatic factors had significant effects on plant species turnover of the shrubland communities in northern mid-subtropical China. With the increase of altitude, slope, soil total nitrogen content and gross domestic product (GDP), species turnover rate increased significantly. Mean annual air temperature and the distance to road had no significant effects on species turnover. The species turnover rate decreased when soil pH became too acidic or too alkaline, and the rate reached the maximum value when pH was 5. Climate, soil, topography, and human disturbance explained 33.55% of the species turnover deviances, of which, soil accounted for 26.54% of the GDM deviances, while climate and topography, human disturbance accounted for 13.39% and 3.17% of the GDM deviances, respectively. Soil pH contributed 37.28% of the deviances to the species turnover of shrubland community. In conclusion, environmental factors (especially soil pH) were the major drivers of the species spatial turnover in northern mid-subtropical shrubland communities.

Aims Subalpine dark coniferous forests are an important representative of the cold-temperate coniferous forests in China. Dark coniferous forests dominated by spruce (Piceaspp.) and fir (Abies spp.) are the main body of subalpine forests on the eastern edge of the Qingzang Plateau and an important ecological defense in the upper reaches of the Yangtze River in China. In this study, we examined the community composition and structure of such a dark coniferous forest based on the first census data of the 25.2 hm² Wanglang forest dynamics plot in western Sichuan.

Methods The plot was established following the standard protocol of Forest Global Earth Observation Network (ForestGEO) and all free-standing stems with diameter at breast height (DBH) ≥ 1 cm were tagged, mapped, measured and identified to species.

Important findings A total of 56 574 individuals belonging to 46 species, 27 genera and 15 families are tagged, including 4 coniferous species, 6 evergreen broad-leaved species and 36 deciduous broad-leaved species. There are 13 rare species (≤1 individuals per hm²), accounting for 28.26% of the total number of species and 0.16% of the total number of individuals in the plot. Abies fargesiivar. faxoniana(9 440 individuals) and P. purpurea (1 645 individuals) are the dominant and constructive species in canopy, accounting for 26.03% and 10.69% of the total importance value, and 55.22% and 24.84% of the total basal area (37.87 m²·hm^-2), respectively. The number of individuals of deciduous broad-leaved species accounted for 78.48% of the total individuals. Among them, Philadelphus purpurascens, Lonicera nervosaand Euonymus frigidusare the dominant species in shrub layer. The number of individuals of evergreen broad-leaved species is 268, and all these species belong to genus Rhododendron. The composition of the size distribution shows typical characteristics of old-growth forests. Picea purpurea is the largest tree species (max DBH = 127.07 cm) and the mean basal area (0.14 ± 0.18) m² is much higher than that of A. fargesiivar. faxoniana(0.056 ± 0.11) m². The size class distribution of all woody species shows an inverse J-shaped distribution, indicating that the community is in a stable and healthy recruitment state. Results of the point pattern analysis reveal that the five dominant tree species (important values ≥5) all show aggregated distribution patterns. However, as the spatial scale increases, all five species tend to be randomly distributed. The results of this study provide basic information for future studies on the diversity maintenance and regeneration mechanisms of subalpine dark coniferous forests in western Sichuan, and the conservation and management of this unique forest ecosystem.

Aims Aboveground biomass (AGB) is one of the most important factors affecting grassland ecosystem function and is commonly measured in grassland research. AGB is often measured using the harvest method, which can cause great disturbance to plant communities, especially for those long-term monitoring plots. A non-destructive method for AGB estimation is thus needed.

Methods Here, we conducted field measurements at a land-use manipulation experiment in a typical steppe in Nei Mongol, China. We obtained the fractional vegetation cover (FVC) using digital photographs. We also measured leaf area index (LAI), vegetation height, and plant species richness. Three different models were used to estimate AGB: univariate regression model, stepwise regression model, and random forest model.

Important findings We found that FVC, LAI, mean vegetation height, maximum vegetation height and richness were highly correlated with AGB variation. AGB can be accurately predicted by a stepwise regression model developed based on the local plant community. The determination coefficient (R²) and root-mean-square error (RMSE) of the stepwise regression model can reach 0.91 and 35.60 g·m^-2, respectively. Overall, our study provides a rapid and non-destructive method for AGB measurement that can be used as an alternative to the traditional harvest method.

Aims Livestock grazing is one of the most important factors affecting grassland plant diversity. However, the information on the effects of different livestock types and their grazing behaviors on grassland plant diversity and community composition are less available. A better understanding of the changes in plant diversity and community composition in response to the grazing of various livestock types is essential to the management and preservation of grassland biodiversity.

Methods We conducted a grazing experiment in a typical steppe of Nei Mongol to examine the effects of different livestock species (cattle, goat, sheep) and their behaviors (forage selection and grazing aggregation) on plant diversity (i.e., α, β and γ diversity) and community composition.

Important findings Our results showed that: (1) cattle, goat, and sheep grazing all increased plant α, β, and γ diversity at moderate grazing intensity, and the increase was the largest and significant under cattle grazing. (2) Three livestock species all changed community structure; sheep grazing reduced the relative abundance of dominant short grass Cleistogenes squarrosa, which is in contrary to the changes in community structure induced by cattle and goat grazing. (3) Cattle and goat grazing significantly reduced the aboveground biomass of dominant species, including tall grasses Leymus chinensis and Stipa grandis and short grass C. squarrosa, while sheep grazing only decreased that of short grass C. squarrosa. Cattle grazing also had a lower spatial aggregation than that of goat and sheep. (4) Plant diversity decreased with the increase of the aboveground biomass of either tall or short dominant species, indicating that livestock grazing promoted plant species diversity by reducing plant aboveground biomass of dominant species. (5) Plant diversity decreased with the increase in spatial aggregation of livestock grazing, indicating a lower aggregation benefiting plant diversity maintenance. Overall, our study suggests that grazing animal types should be considered along with grazing intensity in the development of grazing management regime for better conservation and sustainable use of the grassland resources.

Alpine shrublands, as a zonal vegetation, are widely distributed on the Qingzang Plateau, and play ecological functions such as soil and water conservation, conservation of water resources, and biodiversity protection in the regional ecosystem. This study used a unified and standardized method to set up 58 quadrats to investigate the species composition, quantitative characteristics and habitat information of the main alpine shrublands of the Haizi Mountain in Batang, China. Based on “Vegegraphy of China” compilation and research standards, the alpine shrublands in this area can be divided into three vegetation types, 11 alliances, and 21 associations. This paper presents descriptions on the characteristics for each association and provides the original data from all survey plots.

Aims The karst ecosystem in southwest China is fragile and easily degraded by disturbance. However, the process and mechanism of karst shrub tussock responding to grazing disturbance in the early stage of restoration are still poorly understood.
Methods In this study, four grazing intensity of heavy, moderate, light and none grazing were selected in shrub tussock communities in karst mountains of Mashan County, Guangxi. Species composition and community structure of the vegetation were investigated, and their responses to grazing were further analyzed.
Important findings The results show that: (1) There are 272 species of vascular plants in the sample plots, belonging to 77 families and 200 genera. Poaceae, Asteraceae, Fabaceae and Verbenaceae are the dominant families. With the increase of grazing intensity, the number of families, genera and species in the shrub layer decreased monotonously. However, in the herb layer a single peak was shown in the light grazing area. (2) The increase in grazing intensity did not significantly change the dominant species, but the important values of species changed. For example, the important values of shrub Vitex negundo, herbaceous invasive species Chromolaena odorata and Bidens pilosa, increased with the increase of grazing intensity. (3) Non-metric multi-dimensional scaling (NMDS) analysis showed that grazing led to the vegetation homogenization of shrub layer, and the species composition of most plots tended to be similar, but the species composition of the same grazing gradient also had great differences. Species in the shrub layer were mainly affected by grazing intensity and rock exposure rate, while species in the herb layer were affected by terrain and soil factors such as altitude, soil organic matter content, soil pH, in addition to grazing intensity. (4) Community height, coverage of shrub layer and aboveground biomass decreased significantly with the increase of grazing intensity. The response of community structure in shrub layer to grazing intensity was more obvious than that in herb layer, which may be related to the preference of goats to eat shrubs. Overall, the increase in grazing disturbance intensity will drive the simplification, sparseness and dwarfing of the species composition and community structure of shrub tussock, thereby significantly reducing aboveground biomass and enhancing the potential risk of vegetation degradation in karst mountains, and further hindering natural recovery of karst ecosystem.

Plot-based data are an important foundation for studying plant community characteristics and compiling vegetation monographs, vegetation map, and vegegraphy. It is the key data source of studies in vegetation ecology. To understand the species composition, community characteristics, and distribution pattern of special plateau vegetation on the Qingzang Plateau (QZP), this study uses the data of 338 sites including 758 plots in different regions of the QZP from 2018 to 2021 to analyze the species composition, floristic characteristics, and vegetation classification of plateau plant communities. A plot-based dataset of plant community on the QZP is then established. The 758 plots have 837 plant species belonging to 279 genera from 65 families in the alpine and temperate vegetation communities. The largest number of species are found in five families: Asteraceae (134 species), Poaceae (88 species), Fabaceae (75 species), Rosaceae (43 species), and Cyperaceae (40 species), as well as five genera: Artemisia (29 species), Pedicularis (27 species), Saussurea (25 species), Astragalus (23 species), and Poa (23 species). The floristic composition is mainly temperate (145 genera) and cosmopolitan (36 genera). The growth forms of the species are mainly herbs (83.51%) and shrubs (10.87%), and the life forms of herbs and woody plants are mainly perennial herbs (88.23%) and deciduous shrubs (83.67%), respectively. A total of 338 sites can be divided into four vegetation formation groups, 10 vegetation formations, 20 vegetation subformations, 78 alliance groups, and 117 alliances, in which 34 are steppe alliances, 33 are meadow alliances, 33 are desert alliances, 14 are shrubland alliances, and 3 are coniferous forest alliances. This dataset covers most of the alpine shrubland, meadow, steppe, desert, and temperate steppe, desert vegetation regions of the QZP. This work provides a solid foundation for exploring the vegetation characteristics and regularity of vegetation zonal differentiation and determining the impacts of climate change and human disturbances on alpine vegetation and their ecological restoration. The dataset also provides a reference for the updating of the next generation of China's vegetation map.

Aims The ecological mechanisms underlying species compositional differences among communities are crucial to understanding and predicting biodiversity changes. One of such mechanisms is the spatial structure independent of ground-level habitat (e.g., soil nutrients and topographic parameters). However, the primary drivers of this spatial structure are still unclear. Forest canopy structure can alter understory microclimates, which in turn influences the spatial structure and species compositional differences. We know little so far about such influence of the forest canopy structure. This gap has hindered our understanding of the ecological mechanisms underlying species compositional difference.

Methods The study was conducted in a 20 hm² evergreen broadleaf forest plot in the Tiantong region, Zhejiang Province, Eastern China. UVA-based LiDAR was used to estimate the high-precision forest canopy structure of the Tiantong plot. The redundancy analysis and the variance decomposition method were used to explore the relative importance of forest canopy structure and other potential factors on community species composition.

Important findings Our research showed that: (1) In the case of excluding the effect of canopy structure, the spatial structure independent of the ground-level habitat was one of the main contributors to the species compositional differences in the Tiantong plot. It explained 25.2%, 28.1%, and 8.0% of the variation in species composition at the scales of 100 m²,and 8.0% of the variation in species composition at the scales of 100 m² Our research showed that: (1) In the case of excluding the effect of canopy structure, the spatial structure independent of the ground-level habitat was one of the main contributors to the species compositional differences in the Tiantong plot. It explained 25.2%, 28.1%, and 8.0% of the variation in species composition at the scales of 100 m², 400 m²,400 m² 400 m², and 2 500 m²,and 2 500 m² and 2 500 m², respectively. (2) Including the effect of forest canopy structure significantly reduced the explanation power of the spatial structure by about 1/3 (26.2%-36.0%). (3) Among canopy structure factors, canopy height had the most significant influence on species composition, followed by internal canopy structure. With the increase of the plot scale, the effects of canopy height decreased while the impacts of internal canopy structure increased. In conclusion, our study demonstrated that canopy structure is one of the main drivers of spatial structure independent of ground-level habitat. Our results also clarify the relative importance of canopy height and internal canopy structure on species composition and provide new perspectives to understand the ecological mechanisms underlying species compositional differences among forest plant communities.

Aims Juniperus community is an important component of natural forest resources in the Three-River-Source Region, which is significant in maintaining biodiversity and ecological security on the Qingzang Plateau. Yet, the information on the characteristics of the Juniperus community is lacking due to their special geographical location and varied topography. In this study, the main vegetation types of Juniperus community were investigated, and the main characteristics of each community type were described quantitatively by analyzing data from 53 plots. Methods Based on the analysis of forest resources inventory data in the Three-River-Source Region, the representative distribution area of Juniperus was selected to set up 7 sites, a total of 53 plots. Through the investigation of field communities and plot properties, the importance of each species was quantified and calculated. The principle of life form and dominance methods in Vegetation of China were used to determine community types. Important findings (1) The Juniperus plant community in the Three-River-Source Region was divided into 6 alliances, and then further divided into 15 associations. (2) In total, 142 species of seed plants were recorded, which was belonged to 34 families and 90 genera. Among them, Compositae was the major family, accounting for 16.20% of the total species. (3) The vertical structure of the community was obvious, in which the dominant species in the tree layer was single. The dominant species in the shrub layer were Berberis diaphana, Potentilla glabra and shrubby Juniperus tibetica. The herb layer were dominated by Carex and Pedicularis. (4) Among the geographical elements of seed plant species, the Temperate distribution accounted for 52.59% of the total species, while the rest was Chinese endemic species accounting for 47.41%. Temperate Asian, East Asian and Central Asian were the dominated areal-types in the Temperate distribution. Furthermore, the floristic elements of Hengduanshan flora and Tanggut flora were mixed formed the unique characteristic areal-type in the region.

Ostryopsis davidiana shrubland is one of the most important types of deciduous broad-leaved shrublands that widely occur on mountain sites in northern and northwestern China. Determination of the distribution and characteristics of the O. davidiana communities helps facilitate the biodiversity conservation and establishment of eco-safety buffer on the Mongolian Plateau. In this study, we investigated the O. davidiana shrubland communities across 37 sites in Nei Mongol, and identified the community characteristics, including species composition, ecological traits and classification of O. davidiana alliance based on site survey data collected during 2016-2020. A total of 300 vascular species, belonging to 158 genera from 52 families, were recorded, consisting 298 angiosperm species belonging to 156 genera from 50 families and 2 fern species belonging to 2 genera from 2 families. Perennial herbs are the dominant life form, accounting for 73% of the total species, and mesophytes are the dominant water ecological type, accounting for 65% of the total species. Temperate plants contributed largely to the geographical floristic composition, with majority of the species being East Palaearctic, followed by East Asia element. Most of plant species in the O. davidiana communities were rare species. Based on the survey data, the O. davidiana alliance in Nei Mongol could be divided into 3 association groups and 17 associations.

Aims Grazing exclusion is an important intervention for restoring degraded grasslands. Understanding the changes of grassland productivity and plant diversity during the long-term grazing exclusion succession, as well as the relationship between diversity and productivity, are helpful for grassland restoration management and utilization.

Methods This study was conducted in a typical grassland system with a long-term grazing exclusion gradient, located at Yunwu Mountain National Nature Reserve in Ningxia Huizu Autonomous Region. The grassland communities under continuous grazing, 9 years of grazing exclusion, 26 years of grazing exclusion, and 34 years of grazing exclusion were chosen as the study objects. We tracked changes in aboveground net primary productivity (ANPP), species diversity and functional diversity, and quantified the relationships between diversity and productivity.

Important findings The results showed that grazing exclusion significantly increased ANPP, litter biomass, functional richness, and functional dispersion of typical grassland, but did not alter species richness, Shannon- Wiener index and functional evenness. In contrast, Simpson dominance index and Pielou evenness index significantly decreased after long-term grazing exclusion (34 years). In addition, grazing exclusion showed diverse effects on community-weighted means of different functional traits. The results of random forest model and variance partition analysis indicated that community-weighted mean functional traits accounted for 70.70% of ANPP variation, and plant height was identified as the most important trait. Functional diversity explained 36.86% of ANPP variation, mainly contributed by functional richness. In contrast, species diversity only explained 14.72% of ANPP variation. Therefore, the contribution of mean trait values and functional diversity to ANPP was much higher than that of species diversity in grassland after grazing exclusion. We suggest that community mean trait values and functional diversity should be incorporated into the studies of plant community dynamics during restoration succession, which will contribute to a comprehensive understanding of the relationship between plant diversity and ecosystem function, and provide basis for better realization of ecological restoration goals.

Aims Canopy gaps are a vital part of forest regeneration and succession. This paper aims to reveal the sources of functional trait variations and their relative contributions under forest canopy gaps. This will help to clarify the response of the plants to canopy gaps.
Methods The study was conducted in a natural forest of Castanopsis kawakamii in the central subtropical zone. Nine permanent plots with different sizes were set up under canopy gaps of this forest. The relative contributions of the gaps, species, and individuals to leaf trait variations were investigated using variance decomposition. Linear regression was used to analyze the importance of community mean trait variation and inter- and intraspecific trait variation among the different sizes of canopy gaps.
Important findings The variations of specific leaf area, leaf dry matter content, leaf thickness, and chlorophyll content of plants under canopy gaps were dominated by interspecific trait differences. Leaf nitrogen content was mainly varied within species, while the leaf phosphorus content was most affected by the size of canopy gap. The leaf phosphorus content had a significant positive correlation with gap size. This correlation may be mediated by the positive effect of soil temperature and hydrolyzed nitrogen and the negative effect of available phosphorus content. With the increase of canopy openness, the change of community phosphorus content was mainly caused by intraspecific trait variation, in which the dominant species played an important role. In conclusion, plant functional traits were still dominated by interspecific trait variation (41% on average) in the Castanopsis kawakamii natural forest, but the changes in community traits along the gap size gradients were mainly originated from intraspecific trait variation, which responded to the environmental changes through plant phenotypic plasticity, especially for dominant species.

Aims The study of the pattern of biomass variations and their drivers along environmental gradients commonly contributes to the understanding of plant’s adaptability to environmental changes, further explains the spatial differences in vegetation and ecosystem processes. We investigated the biomass latitudinal patterns of plant communities and its components and revealed the quantitative relationships of biomass with climatic, soil and community structure as well as species diversity.

Methods In order to analyze the variation patterns of biomass along the latitude gradient and the drivers, we set up a total of 101 plots (4 m × 6 m) across nine region along latitude in the arid valley of southwest China (23.23°-32.26° N), to investigate biomass and species composition of plant communities and its components.

Important findings In the arid valley, the average biomass of community was (17.05 ± 1.09) t·hm^-2, of which the average biomass of shrub, herb and litter were (11.51 ± 1.03), (2.11 ± 0.21) and (3.41 ± 0.34) t·hm^-2, respectively, with each of them accounting for 60.2%, 15.6%, and 24.1% of the community biomass. With the increase of latitude, community biomass increased significantly. Shrub biomass and their proportion also increased significantly, herb biomass and their proportion remained consistent, whereas litter biomass decreased significantly. The changes of shrub dominance and abundance were the main internal factor for vegetation biomass variation along the latitude gradient. Additionally, compared with soil factors, climatic factors had a more significant impact on the biomass changes of communities and its components.

The central Guizhou Plateau is located in the center of the karst region of southwestern China. The typical vegetation type is karst mixed evergreen and deciduous broad-leaved forests on this distinct landform. Due to human disturbances, the main existing vegetation is secondary vegetation in this region. Based on the primary plot-level data obtained from fieldwork during the growing season from 2007-2020, we systematically studied the community characteristics and the classification of these karst forests. The results showed that the typical karst forests are co-dominated by evergreen trees (e.g., Cyclobalanopsis, Itea, Lithocarpus, Machilus and Cinnamomum species) and deciduous trees (e.g., Platycarya, Carpinus, Celtis and Quercus species). Moreover, 585 vascular plants belonging to 318 genera and 124 families were recorded in the 86 forest plots, among which there were 65 ferns species belonging to 27 genera and 11 families, and 520 angiosperm species belonging to 291 genera and 113 families. The karst forests show high diversities of species composition and community type. Based on the dominance principle, these karst forests were classified into 11 alliance groups, 44 alliances and 83 associations.

Amygdalus mongolica is a kind of rare and endangered plant in China, which has high academic value and diagnostic significance for the evolution of the flora and the biodiversity and stability of the ecosystem. The 14 Amygdalus mongolica sites were set up to investigate its community composition in Ningxia. The results showed that the 74 plant species in Amygdalus mongolica sites in Ningxia belong to 53 genera from 28 families were recorded, including 2 trees, 21 shrubs, 11 subshrubs, 36 perennial herbs and 4 annual herbs. TWINSPAN divides 14 Amygdalus mongolica sites into Amygdalus mongolica - Herbs Desert, Amygdalus mongolica - Subshrubs Desert Associations Group and Amygdalus mongolica - Stipa tianschanica var. gobica, Amygdalus mongolica - Oxytropis aciphylla, Amygdalus mongolica - Stipa breviflora, Amygdalus mongolica - Ajania achilleoides, Amygdalus mongolica - Elymus alashanicus, Amygdalus mongolica - Ajania achilleoides + Stipa breviflora 6 Associations. Our study will provide basic data for the protection, utilization and compilation of vegetation of Amygdalus mongolica.

Ephedra rhytidosperma is an endemic and endangered plant in East Alxa, and its community is one of the unique desert plant communities in the Helan Mountain. In this paper, we investigated 16 plots of the E. rhytidosperma community in 2019 and analyzed its flora characteristics, applied TWINSPAN to classify community types. Results showed that: 1) The species composition of E. rhytidosperma community was dominated by Gramineae, Compositae, Leguminosae and Zygophyllaceae, belonging to 13 families, 24 genera and 27 species. 2) The main life forms of E. rhytidosperma community were perennial herbs (44.44%) and shrubs (29.63%); the main floristic geographic elements were Palaeo-Mediterranean element (44.44%) and East Asia element (33.33%); the main ecological types of water were xerophyes (40.74%) and super-xerophytes (37.04%). 3) Based on the life forms and species composition, the E. rhytidosperma communities were divided into two major Association Groups. Ephedra rhytidosperma - Semi-Shrub Desert and Ephedra rhytidosperma - Herb Desert, which were further divided into 3 Associations: Ephedra rhytidosperma - Convolvulus tragacanthoides - Lespedeza davurica Semi-Shrub and Herb Desert, Ephedra rhytidosperma - Convolvulus tragacanthoides - Ptilagrostis pelliotii Semi-Shrub and Herb Desert and Ephedra rhytidosperma - Ptilagrostis pelliotii Semi-Shrub and Herb Desert.

The karst forests of Junzi Mountain are within the territory of Shizong County in east Yunnan Province, belonging to the vegetation zoning of semi-humid evergreen broadleaf forests and Pinus yunnanensis forests of the mid- and eastern Yunnan Plateaus. These forests are predominantly secondary and typical representatives of the forest remnants in the eastern edge of the zonal vegetation. In order to determine the vegetation types and community characteristics of the karst forests in Junzi Mountain, systematic plot surveys were carried out for species composition, quantitative characteristics and habitat information of all plant communities. Based on analysis of the survey data from 29 plots and the revised vegetation classification system of China, these karst forests could be categorized into 4 vegetation formations, 16 alliances and 27 associations. This paper presents descriptions on the characteristics for each association and provides the original data from all survey plots.

The main vegetation types of Desert Grassland Nature Reserve in Qitai, Xinjiang were investigated in this paper. Based on the data from 65 plot samples, the characteristics of the main desert plant communities from the main vegetation types were quantitatively described. The results showed that, the vegetation in this reserve can be divided into 12 major plant community types: Haloxylon ammodendron Simi-Arbor and Shrub Desert Alliance, Ephedra przewalskii Simi-Arbor and Shrub Desert Alliance, Gymnocarpos przewalskii Simi-Arbor and Shrub Desert Alliance, Reaumuria soongarica Simi-Arbor and Shrub Desert Alliance, Iljinia regelii Semi-Shrub and Herb Desert Alliance, Anabasis brevifolia Semi-Shrub and Herb Desert Alliance, Tamarix laxa Deciduous Broadleaf Shrubland Alliance, Kalidium foliatum Semi-Shrub and Herb Desert Alliance, Ajania fruticulosa Semi-Shrub and Herb Desert Alliance, Achnatherum splendens Tussock Grassland Alliance, Leymus angustus Tussock Grassland Alliance, Phragmites australis Tussock Grassland Alliance. Finally, 15 associations were derived from these 12 major community types.

The ecological “green-core” area of Changzhutan urban cluster is located in the center of red soil hilly region of Southern China, and the northern vegetation sub-zone of mid-subtropical evergreen broad-leaved forests. In this area, the vegetation is dominated by secondary forests, and the vegetation types are diverse. It is representative of the current vegetation in red soil hilly region of South China, and hance can provide a good platform for the research of regional vegetation succession dynamics and vegetation restoration. We set up 50 plots with a unified and standardized method, and then the species composition, quantitative characteristics, and habitat information of the main vegetation types in the area were investigated. The importance values of species in the tree layer, shrub layer and herb layer were calculated, and the vegetation type of each community were identified and named according to the compilation and research standard of Vegegraphy of China. The community species composition and characteristics were described, and the original data of 50 plots divided into 10 vegetation formations, 22 alliances and 33 associations were provided, including 43 forest plots, 5 shrub plots, 1 grassland plot and 1 swamp plot.

Aims Understanding the population quantity and distribution of a drought-resistant plant, Keteleeria davidiana, can assist the protection of this rare and endangered species.
Methods The K. davidiana forest communities were investigated in dry land of 6 townships in Xinping County, Yunnan Province, in three 20 m × 20 m plots for each township, and analyzed for structural characteristics in consideration of species composition and life-forms.
Important findings We found 163 vascular plants belonging to 131 genera and 58 families in the plots with a total area of 7 200 m². The communities are classified into 12 zonal types containing predominantly tropical and endemic species to China, dominated by the tropical components. Trees and shrubs (accounted for 62.58%) are dominant life-forms, followed by perennial herb. Based on the foundation species and life-form, the data of 18 vegetation plots were classified into 3 formations and 17 community types. The analysis of stumpage structure showed that the population structure of K. davidiana tended to recess, and the natural populations are small. If lacks sufficient regeneration seedlings, the K. davidiana trees would decline and diminish from the communities.

Dashiwei Tiankeng group is rich in plant diversity resources. In order to further understand the plant community characteristics of the Dashiwei Tiankeng group, a total of 25 sample plots were set up in different positions (mouth pit, waist pit, bottom pit) and outside the pit in the Dashiwei Tiankeng group. 269 species of vascular plants belonging to 176 genera and 89 families were investigated by the sampling method, and Lauraceae, Rosaceae, Urticaceae and so on are the most abundant families in the community. The stratification is obvious and the distribution of dominant species was more uniform in each layer of the community. Among them,Manglietia aromatica, Choerospondias axillaris, Handeliodendron bodinieri were dominant species in the tree layer; Metapanax davidii, Itea yunnanensi were dominant species in the shrub layer, and the dominant herb layer is Elatostema. The seasonal phase is obvious of the community. It is mainly evergreen and deciduous broad-leaved mixed forest, with the evergreen broad-leaved forest at the bottom pit and the deciduous broad-leaved forest at the edge of mouth pit. The life form spectrum of the community is 55.76% for phanerophytes, 29.74% for aboveground plants, 6.69% for aboveground plants, 5.21% for cryptophytes and 2.60% for annual plants. The characteristics of the community types, composition and structure of Tiankeng were analyzed in this paper, which provided basic information for studies of plant communities in Dashiwei.

Stipa sareptana var. krylovii alliance is one of the typical steppes endemic to Central Asia. The eastern border of its distribution is adjacent to the meadow steppes on the Hulunbeir Plateau, the western border extends to the desert steppes on the Ulanqabu Plateau and Tianshan Mountains, and the southern border lies among the warm temperate steppes on the Loess Plateau. The distribution of this alliance also spreads into the alpine steppes on the eastern margin of the Qinghai-Xizang Plateau. The broad its distribution suggests that S. sareptana var. krylovii alliance has wide ecological adaptability. In this study, we described and analyzed the eco-geographical distribution, community characteristics and classification of S. sareptana var. krylovii alliance based on data from 117 plots. The results showed that there are 336 seed plants belonging to 36 families and 131 genera in these plots. The families with more than 15 species are Gramineae, Compositae, Leguminosae, Rosaceae, Chenopodiaceae and Liliaceae. Among all species in these plots, 91.67% are rare species with occurrence frequency smaller than 20%. Besides S. sareptana var. krylovii, the most common species in this alliance include Cleistogenes squarrosa, Heteropappus altaicus, Agropyron cristatum, Koeleria cristata, Potentilla bifurca, Salsola collina, Allium tenuissimum and Leymus chinensis. In addition, hemicryptophytes are the most common life form within the surveyed plots, accounting for 66.37% of all species. Xerophytes are the most common water ecological type, accounting for 61.19% of all species. East Palearctic element was the major floristic geographical element, accounting for 33.33% of all species. Based on the China Vegetation Classification System, S. sareptana var. krylovii alliance could be classified into 6 association groups and further into 45 associations.

The Stipa bungeana alliance is one of the main steppe types in Eurasian. Endemic to China, the alliance is mainly found in the Loess Plateau and the adjacent areas, but its range of distribution has been noted to decline and become highly fragmented due to conversion to cropland or at unstable successional stages. In this study, we described and analyzed the eco-geographical distribution, community characteristics, and vegetation classification of S. bugneana alliance based on data from 108 plots surveyed during 2013-2019. Results show that S. bungeana alliance is currently distributed in northern Shaanxi, southern Ningxia, eastern and central Gansu, northern Shanxi, the loess hills in the south of Yinshan Mountains and the Erdos Plateau. This alliance occurs mainly on loess soils or kastanozems, along elevation ranging from (1) 631 to 3 174 (4 098) m. Two hundred and fourteen plant species from 37 families and 109 genera were recorded across the 108 plots, with most of them being rare species in the alliance. There are more hemicryptophytes and perennial forbs than other life forms. Xerophytes, especially meso-xerophytes and typical xerophytes, have higher representation in species richness than mesophytes. Among the 10 geographical floristic elements, the East Asia element, the East Palearctic element and the central Asia element were the three dominants. The height, cover, biomass and species richness vary greatly across the plots because those variables are highly related to the moisture and disturbance intensity of the habitats. Based on China Vegetation Classification System, S. bugneana alliance could be classified into seven association groups and 37 associations.

Aims Shrub encroachment is a critical ecological problem in arid and semi-arid ecosystems worldwide. The effects of shrub encroachment on ecosystem structure and function of grasslands are complicated and need to be explored in future studies. Our objective is to examine the effects and pathways of shrub encroachment on ecosystem structure and function in a typical steppe of the Inner Mongolia grassland.
Methods Three grassland sites with different degrees of shrub encroachment (i.e. light, moderate, heavy) were selected in the Xilingol Nei Mongol, of which Caragana microphylla was the dominant shrub. Species richness and composition, aboveground net primary productivity (ANPP), soil property, and plant functional traits of dominant species were determined in this study. In addition, species diversity, functional attribute diversity, community-weighted mean traits, and vegetation leaf and soil carbon and nitrogen pools were further calculated.
Important findings 1) The species richness, functional attribute diversity and community-weighted mean traits differed significantly among three grassland sites, and species diversity and functional diversity were relatively higher in the moderate shrub-encroachment site, indicating moderate shrub-encroachment favors biodiversity maintenance. 2) The aboveground net primary productivity of heavy shrub-encroachment grassland was significantly higher than those of light and moderate shrub-encroachment grasslands, which was mainly due to a shift in functional group composition, that is, the proportion of annuals and biennials to perennial grasses and forbs increased greatly with intensifying shrub encroachment. The vegetation leaf and soil carbon and nitrogen pools differed little among three sites. 3) Shrub encroachment did not directly affect ecosystem function, including ANPP, vegetation and soil nutrient pools, but it indirectly affected them through pathways of the shift in functional group composition and changes in soil property and functional diversity. Particularly, the shift in functional group composition and intensified soil drought and basification was separately important biotic and abiotic factors for variations in ecosystem function.

The Beishan Mountain of Jinhua is located in the northern part of the mid-subtropical region. In vegetation division, this region belongs to the northern sub-zone of mid-subtropical evergreen broad-leaved forest vegetation belt. The vegetation in this mountain is a secondary forest restored from a severe deforestation. It is currently in a rapid process of positive succession. Thus, this region is suitable for studying the dynamics and succession mechanisms of plant communities and the restoration of degraded ecosystems. To further understand the community characteristics of the main vegetation types in Beishan Mountain, we surveyed the main plant communities on its southern slope with a fixed plot method (the plot area is 30 m × 30 m for forests and 20 m × 10 m, 30 m × 10 m for shrubs) based on the internationally accepted forest survey approach used in the survey of dynamic forest plots. The species composition, quantitative characteristics and habitat information of all plant communities were investigated and recorded. The importance values of trees and shrubs were calculated. The community types and their characteristics were analyzed. The spatial distribution maps of the major trees and shrubs in each plot were also drawn. In the present study, detailed community data for 24 sampled plots representing 11 formations were presented (consisting of 21 forest plots and 3 shrub plots).

Aims Understanding the spatial patterns and maintenance mechanisms of biodiversity is one of the central issues in ecology and biogeography. Specifically, altitudinal patterns of biodiversity have been widely explored to represent to mimic the latitudinal patterns. However, previous studies on altitudinal patterns of plant diversity have focused mainly on the taxonomic diversity, with less attention paid to the comprehensive information of taxonomic, phylogenetic evolution and functional traits. In this study, we explored maintenance mechanisms of diversity of forest communities in Mount Guandi, by comparing the altitudinal patterns of taxonomic, phylogenetic and functional diversity, based on the systematic investigation of forest communities.
Methods 52 forest plots, each with an area of 30 m × 20 m and divided into six subplots (10 m × 10 m), were investigated along the altitudinal gradient (1 409-2 150 m) in Mount Guandi, Shanxi. Name, diameter at breast height (DBH) and height were identified and measured for each tree stem with DBH ≥3 cm at each plot; name, average height, coverage and basal diameter for each shrub species were identified and measured in two of the six subplots; name, abundance, coverage and average height for each herbaceous species were identified and measured for one quadrat of 1 m × 1 m in each subplot. The indices of taxonomic, phylogenetic and functional α and β diversity were then calculated.
Important findings Species richness (S), phylogenetic diversity (PD) and functional richness (FRic) increased along the altitudinal gradient, especially in altitudes above 1 800 m. Total β diversity (β_total) and replacement β diversity (β_repl) increased, while the richness difference (β_rich) decreased, along the altitudinal gradient. The patterns of taxonomic, phylogenetic and functional diversity were significantly different between woody and herbaceous plants. S and Shannon-Wiener diversity (H′) of herbaceous plants increased more obvious along the altitude than those of woody plants. Topographic factors regulated the pattern of the herbaceous plant richness, while historical process regulated the woody plant richness. Along the altitude, β_total increased more obvious for the woody plants than for the herbaceous plants. β_repl and β_rich of woody plant showed a unimodal pattern and U-shaped pattern, while those of herbaceous plants increased or decreased, respectively. Taxonomic, phylogenetic and functional β diversity of both woody and herbaceous plants among communities increased with the environmental and geographical distances. Environmental distance had a relatively stronger effects than geographical distance on β diversity of woody plants, while environmental distance and geographical distance jointly influenced β diversity of the herbaceous plants.

Aims Explore the distribution pattern and the processes controlling the assembly of the Juglans mandshurica dominated forests in North China.
Methods We investigated 84 plots, each with an area of 20 m × 30 m, for the J. mandshurica forests in the North China. We analyzed demography of the J. mandshurica based on its diameters, and applied canonical correspondence analysis (CCA) to explore the relationship between environment and species composition of different formations of the J. mandshurica forests. We then calculated phylogenetic index, i.e., net relatedness index (NRI) and nearest taxonomic index (NTI) and Gaussian Kernel Density Estimation (Gaussian KDE), for each plot to explore the rules controlling community assembly of these forests.
Important findings The population of J. mandshurica is relatively young in the Northern China, with a mean diameters at breast height (DBH) of 5.36 cm. Distribution of J. mandshurica in North China varied significantly with altitude, slope, slope position and human disturbance. Most of the J. mandshurica located at the low part of the massif with lower altitude and less human disturbance. In North China, niche related processes regulated species coexistence of Form. J. mandshurica, with competition controlled the community assembly in Hebei, Shaanxi and Tianjin, while environment filtering dominated in Beijing and Shanxi.

Aims Larch forests are important for timber harvesting and water-soil conservation in North China. To explore the distribution, community structure and species diversity of larch forests is important for the vegetation conservation and sustainable utilization in North China.
Methods We collected species composition and local environment for 215 forest plots dominated by three common larch species, namely, Larix principis-rupprechtii, L. kaempferi and L. chinensis, in North China during 2000-2017. Among these types, L. kaempferi forests are planted, while L. chinensis forests are almost natural, and most of L. principis-rupprechtii forests are natural. Based these data, we used the canonical correspondence analysis (CCA) to explore the relationship between species composition and environment. We also explored the pattern of community structure and species diversity of these three forests in relation to environmental factors.
Important findings Mean annual air temperature (MAT) was the most important factor for the distribution of these larch forests. The proportion of natural forest decreased, while that of planted forest increased, with MAT. Diameter at breast height (DBH) and height distribution of three larch forests were right-skewed, indicating that all of these larch forests are at relatively stable successional stage. Species richness differ remarkably among different larch forests, which was highest in the L. chinensis forests (39.3 ± 17.9), followed by the L. kaempferi forests (37.4 ± 22.4), and lowest in the L. principis-rupprechtii forests (planted forests 27.2 ± 17.7, natural forests 27.5 ± 13.8). Species richness, the maximum DBH and the maximum height decreased with latitudes and longitudes. Species richness, the maximum DBH and the maximum height increased with annual precipitation. However, species richness showed no significant trend, and the maximum height increased, while the maximum DBH decreased, with MAT. The patterns of species richness along geographical and climatic gradients were consistent between the planted, the natural and the overall (including both planted and natural) larch forests. However, the patterns of community structure differed remarkably among planted, natural and overall larch forests. The maximum height of planted forests increased, while that of natural forests decreased, with latitude and longitude. The maximum DBH and height of natural forests decreased, while those of planted forests increased, with MAT and annual precipitation, respectively.

Aims Many competing theories seek to identify the mechanisms behind the community assembly. Niche theory and neutral theory are among the two most competing mechanisms. Exploring factors controlling the patterns of β-diversity is an approach to reveal the underlying mechanisms of community assembly. In this paper, we aim to reveal the β-diversity pattern of understory in planted forests of the central Loess Plateau and to evaluate the relative influences of deterministic (environmental filtering) and stochastic (dispersal limitation) processes on the community assembly.
Methods We sampled in total 107 sites of planted forests spatially spreading over the central Loess Plateau. In each site, three plots (10 m × 10 m) were randomly designed each at a distance of about 50 m. The floristic composition, community structure, and environmental conditions were investigated in each plot. We calculated the dissimilarity (β_sim) of species composition, geographic distance and environmental divergence for each of the 5 671 site pairs. We used random forest (RF) to quantify the influence of the selected factors on species composition, and distance-based multivariate regression method (MRM) to fit the relationship between dissimilarity, geographic distance and environmental divergence. To quantify how and in what extent the environmental filtering and the dispersal limitation influence the species composition among sites, we performed the principle coordinates of neighbor matrices (PCNM) and distance-based RDA (db-RDA) to select the pronounced independent variables. We then partitioned the variance into three parts, namely, 1) independent contributions of geographic distance; 2) independent contributions of environmental divergence; and 3) the joint contribution of both.
Important findings The community similarity declined with increasing geographical distance and environmental divergence. Geographical distance and environmental divergence together explained 47.8% of variance in the dissimilarity in species composition. The spatial variables accounted for 14.1%, while the environmental variables accounted for another 9.8% of the variance in dissimilarity of species composition. Annual precipitation and basal area of trees are the two most important environmental factors influencing the pattern of dissimilarity of species composition. These results implied that both environmental filtering and the dispersal limitation play important roles in shaping the community assembly of the herbaceous layers of planted forests in the central Loess Plateau.