Field surveys were conducted during four campaigns in March 2022, May–June 2022, May–June 2023, and June 2024. May–June was selected as the primary survey time because most species across elevational belts in the region have developed diagnostic vegetative structures and even many have begun flowering, enabling reliable identification. In addition, it coincides with the transition from the dry to the wet season when precipitation is still relatively low and field accessibility is generally high. An additional survey in March 2022 targeted dry-hot valley vegetation, where phenological development occurs earlier under warm and relatively arid conditions.

To capture the major vegetation belts and transition zones shaped by the regional mountain–valley and climatic gradients, we adopted a coverage-oriented field sampling design. Plots were set up across representative mountains and valleys of the HDM and adjacent regions along various longitudinal, latitudinal, and elevational gradients. The survey aimed to cover major vegetation physiognomic types, representative mountain–valley systems, and local transitions among forest, shrubland, and grassland communities. Field logistics, road accessibility, and terrain conditions were also considered during plot selection. Plot size was determined following community physiognomy and stand heterogeneity. The sizes of grassland plots were mainly 1 m × 1 m (91.9 % of grassland plots), of shrubland plots were mainly 5 m × 5 m (70.0 %), and of forest plots were mainly 10 m × 10 m (56.3 %) or 10 m × 20 m (29.6 %). Local adjustments in plot size were made because of terrain constraints, especially slope, and field operability in complex mountain environments. The dominant plot size covered broad spatial and elevational ranges within the surveyed distribution of their corresponding vegetation types (Fig. S1; Table S2 in the Supplement). In forest and shrubland plots, all woody species were recorded, including species name, growth form, phenological period, number of individuals or clumps, height, stem diameter, and crown width. Diameter was generally measured as diameter at breast height (DBH). For individuals <2 m tall or when DBH was not applicable, basal diameter (BD) was recorded. In forest plots, individuals with height ≥5 m were assigned to the tree layer, whereas shrubs and tree seedlings with height <5 m were classified into the shrub layer. In grassland plots, all herbaceous species were recorded, including species name, growth form, phenological period, number of individuals or clumps, maximum leaf-layer height, and coverage. The number of individuals or clumps was used as the count-based abundance measure. For species occurring as discrete individuals, each individual was counted separately. For clumped plants, distinguishable clumps were used as the counting unit, and the number of individuals within clumps was additionally noted when identifiable. In forest and shrubland plots, woody plants were recorded by individual or clump; therefore, the same species could have multiple records within a plot. In grassland plots, herbaceous plants were recorded by species, with each species represented by one record containing the total number of individuals or clumps within the plot.

For each plot, longitude, latitude, elevation, community height and total coverage, as well as disturbance intensity were recorded. The Global Positioning System was used to determine the geographic coordinates. Community height was defined as the maximum height of the dominant vegetation layer within a plot. Specifically, in forest plots, it referred to the visually estimated height of the tallest tree in the tree layer; in shrubland plots, it was measured or estimated as the height of the tallest shrub layer using a tape measure where possible; and in grassland plots, it was measured as the maximum height of the herbaceous leaf layer. Total coverage was visually estimated as the vertically projected percentage cover of all plant species within each plot. Disturbance intensity was assessed directly at four levels: none, weak, medium, and strong. These measurements and estimates followed the same field criteria throughout all survey campaigns and were conducted by experienced vegetation investigators to ensure consistency. In total, 314 plots were surveyed, belonging to 142 forest plots, 110 shrubland plots, and 62 grassland plots (Fig. 2; Table 1). These surveyed plots cover the major geographical space (Fig. 2a), climatic space (Fig. 2b), vegetation types (Fig. 2c), and elevational belts (Fig. 2d) of the study region.

Species were identified following national and regional floras, including the Flora Republicae Popularis Sinicae (Editorial Committee of the Flora of China, Chinese Academy of Sciences, 1959–2004), Flora Yunnanica (Kunming Institute of Botany, Chinese Academy of Sciences, 1977–2006), Flora Xizangica (Integrated Scientific Expedition to Qinghai-Tibet Plateau, Chinese Academy of Sciences, 1983–1987), and Flora Sichuanica (Editorial Committee of Flora Sichuanica, 1981–2012). Final species names were then standardized and validated against the iPlant online taxonomic system (http://www.iplant.cn/, last access: 16 January 2026). In the most recent taxonomy system of Flora of Pan-Himalaya (Zhang, 2020), Kobresia is classified into Carex. Given the ecological importance of Kobresia in alpine zonal vegetation, and in order to maintain consistency with vegetation literatures, we retained Kobresia as a traditional genus name for data analyses, while the dataset provides both names.

Growth forms were classified from field observations following the definitions in Vegetation of China (Editorial Committee of the Vegetation of China, 1980) into tree, shrub, climber, semi-shrub, and herb. Some taxa (e.g., Quercus and Rhododendron) can show both shrubs and small trees, and they were recorded at the plot level according to the observed status. For regional summary analyses, each species was additionally assigned a single predominant growth form based on its most frequent form seen in the field across the dataset. Woody species were further divided by leaf type (needleleaf vs. broadleaf) and phenology (evergreen vs. deciduous). Herbaceous species were categorized into annual, biennial, and perennial life forms. Floristic areal-types of plant families and genera were assigned primarily based on the Areal-types of the World Families and Chinese Genera of Seed Plants (Wu, 1991; Wu et al., 2003), supplemented by the Floristic Statistics and Analyses of Seed Plant from China (Li, 1996) and Dictionary of the Families and Genera of Chinese Vascular Plants (iFlora Initiative of Kunming Institute of Botany, Chinese Academy of Sciences, 2018).

Vegetation classification followed the revised scheme of vegetation classification system of China (Guo et al., 2020), which adopted a three-level hierarchy (vegetation formation, alliance, and association) and emphasizes constructive and dominant species in reflecting the primary structural characteristics of plant communities. For each level, a corresponding supplementary classification unit was defined (vegetation formation group, alliance group, and association group). Dominance was identified using species importance value (IV, %) calculated following Fang et al. (2009): for tree-layer species, IV combined relative abundance, relative height, and relative basal area; for shrub-layer species, IV combined relative abundance and relative height; and for herb-layer species, relative abundance and relative coverage. Relative abundance was calculated from the number of individuals or clumps, and all relative metrics were expressed as percentages of the corresponding plot total. A community was assigned a single dominant species when one species had IV > 75 %. When multiple species showed IV between 10 % and 75 %, species were designated as dominant and sub-dominant in descending order of IV if interspecific IV differences exceeded 10 %, and as co-dominant when IV differences were ≤10 %. When all species had IV < 10 %, the community was treated as lacking a clear dominant species, and thereby species were simply ranked by IV (Wang et al., 2020). Vegetation formation groups were defined by community ecological physiognomy (e.g., forests), and vegetation formations by the life form of the constructive species (e.g., evergreen needleleaf forests). Alliance groups were divided by the genus of constructive species (e.g., Abies forest alliance group), and alliances by the constructive species (e.g., A. georgei forest alliance). Association groups were identified by the constructive species together with the life form of sub-dominant species (e.g., A. georgei – shrub forest association group), and associations were determined by the constructive species and sub-dominant species (A. georgei – Rubus amabilis forest association). In the naming convention, a “–” was used to connect species from different layers, and “+” was to connect multiple species within the same layer (Guo et al., 2020). In addition, two-way indicator species analysis (TWINSPAN) was further used as a complementary numerical classification of the vegetation plots. It is a divisive hierarchical classification method that progressively partitions plots according to differences in species composition and identifies indicator or diagnostic species associated with each split.

The HDM-Plot dataset compiles 14 113 individual records from 314 plots, documenting 1127 plant species (including subspecies and varieties) belonging to 379 genera and 117 families (Table 1). The most species-rich families are Rosaceae (133 species), Ericaceae (93), Fabaceae (66), Asteraceae (63), and Fagaceae (37), occurring in 27.1 % to 71.3 % of plots (Fig. 3a; Table 2). Rosaceae is the most widely distributed family in the dataset, while Fabaceae is also broadly recorded but with a relatively lower plot frequency. Ericaceae and Fagaceae are mainly concentrated in the southern to central parts, and are less frequent toward the northern sector. Asteraceae is more frequently recorded in the central and northern areas, but is sparse in the southernmost part (Fig. 3a). Along the elevational range surveyed, Rosaceae and Ericaceae show broad elevational distributions, with most records concentrated at middle to high elevations. Fabaceae spans the widest elevational ranges, extending from low valleys to alpine areas, but its distribution is mainly centered at low to middle elevations. Asteraceae is distinctly concentrated at high elevations, with a relatively high median elevation. In contrast, Fagaceae is mainly distributed at low to middle elevations and shows a lower elevational distribution center than the other dominant families (Fig. 3c). The five richest genera are Rhododendron (75 species), Berberis (34), Cotoneaster (30), Salix (24), and Quercus (22) (Table 2). Rhododendron, Berberis, and Cotoneaster are broadly distributed across the region, although their records are denser in the southern and central sectors. Salix is more frequent in the northern sector, whereas Quercus is mainly concentrated in the southern to central parts and becomes less frequent toward the north (Fig. 3b). Rhododendron and Berberis are mainly concentrated at middle to high elevations, Cotoneaster occupies a relatively broad middle-elevation range, Salix is centered at higher elevations, and Quercus shows the lowest elevational distribution center among the dominant genera, mainly occurring at low to middle elevations (Fig. 3d).

Taxonomic composition differs among vegetation types (Table 2; Figs. 4–6). Forest plots include 737 species, 239 genera, and 91 families (Table 1). The dominant families are Rosaceae, Ericaceae, Fabaceae, Fagaceae, Berberidaceae, and Pinaceae (Table 2). Rosaceae is mainly represented by shrub genera such as Cotoneaster (23.2 %), Rubus (13.1 %), and Rosa (12.1 %), as well as tree genera such as Prunus (14.1 %). Ericaceae is dominated by Rhododendron (78.2 %), which is commonly shrubs and occasionally small trees. Fabaceae contains a wide range of growth forms, including shrub genera (e.g., Indigofera, Campylotropis, and Caragana), climbers (mostly single-species genera), and occasional tree taxa (e.g., Dalbergia). Fagaceae is composed of Quercus (58.8 %), Lithocarpus (20.6 %), and Castanopsis (20.6 %), and provides constructive species in nearly one-third of forest plots. Berberidaceae only records one genus Berberis and is a vital component of the shrub layer. Pinaceae offers the main needleleaf constructive species in needleleaf forests and mixed forests, dominated by Abies (35.7 %), Picea (28.6 %), Larix (10.7 %), and Pinus (10.7 %). Rosaceae, Ericaceae, Fagaceae, Berberidaceae, and Pinaceae are widely recorded in forest plots, whereas Fabaceae and Berberidaceae have lower plot frequencies and more restricted spatial distributions (Fig. 4a). Rosaceae and Pinaceae occur across a broad part of the region, while Ericaceae, Fabaceae, Fagaceae, and Berberidaceae are more concentrated in the southern to central sectors (Fig. 4a). Along the elevational gradient, Fabaceae and Fagaceae are mainly distributed at low to middle elevations, although both extend upward into middle-high elevational belts. Rosaceae and Ericaceae show broad middle-elevation distributions. Berberidaceae and Pinaceae have higher elevational distribution centers, with records mainly concentrated at middle to high elevations (Fig. 4c). The top five genera are Rhododendron, Berberis, Cotoneaster, Quercus, and Salix (Table 2). Rhododendron, Berberis, Cotoneaster, and Quercus are mainly recorded in the southern to central parts of the study region, whereas Salix is more frequently recorded toward the northern sector (Fig. 4b). Quercus has the lowest elevational distribution center and is mainly concentrated at low to middle elevations, Rhododendron and Cotoneaster occupy broad middle-elevation range. Berberis is more narrowly concentrated at middle to high elevations, while Salix is centered at relatively high elevations among the dominant forest genera (Fig. 4d).

110 shrubland plots survey a total of 321 species from 124 genera and 53 families (Table 1). Dominant families largely overlap with those of forests, with Lamiaceae as a new component. Rosaceae consists of Cotoneaster (32.8 %), Rosa (15.5 %), and Spiraea (13.8 %) and forms the core of deciduous broadleaf shrublands. Ericaceae is strongly dominated by Rhododendron (86.8 %) and typically acts as the constructive species in evergreen broadleaf shrublands. Fabaceae includes Caragana (20.0 %), Campylotropis (16.0 %), and Indigofera (16.0 %), commonly recorded in the dry-hot valley shrublands. Berberidaceae is almost represented by Berberis (94.1 %), with Mahonia recorded but not in forest plots. Lamiaceae is characterized by typical dry-hot valley genera such as Caryopteris (28.6 %), Isodon (21.4 %), and Elsholtzia (21.4 %). Rosaceae is the most widely distributed shrubland family across the study region, whereas Fabaceae and Berberidaceae are also broadly recorded. Ericaceae is more concentrated in the southern to northwestern sectors, and Lamiaceae are mainly distributed in the north (Fig. 5a). Ericaceae has the highest elevational distribution center and is mainly concentrated in high elevations, and Berberidaceae is also mainly distributed at middle to high elevations. Rosaceae spans a broad elevational range but is denser at middle to high elevations, while Fabaceae and Lamiaceae have lower elevational distribution centers and are mainly concentrated at low to middle elevations (Fig. 5c). The top genera are Rhododendron, Cotoneaster, Berberis, Salix, and Lonicera (Table 2). Berberis and Lonicera are widely distributed across the region, whereas Rhododendron, Cotoneaster, and Salix are primarily aligned along a southwest–northeast direction (Fig. 5b). Their elevational distributions are also distinct. Rhododendron and Salix are concentrated at high elevations, with higher median elevations and relatively narrow central distributions. Berberis and Lonicera are mainly distributed at middle to high elevations. Cotoneaster has a lower elevational distribution center, and is mainly concentrated at middle elevations (Fig. 5d).

62 grassland plots investigate a total of 266 species belonging to 38 families and 114 genera (Table 1). The most species-rich families are Asteraceae, Cyperaceae, Ranunculaceae, Gentianaceae, Fabaceae, Rosaceae, and Poaceae (Table 2). Asteraceae is largely represented by Saussurea (23.1 %), Anaphalis (19.2 %), Artemisia (17.3 %), and Taraxacum (13.5 %), consisting of perennial forbs and semi-shrubs that contribute to forb grasslands. Cyperaceae is dominated by tussock Kobresia and rhizome Carex and provide the main constructive species in grassland vegetation (42 plots), especially the zonal species K. pygmaea. Ranunculaceae is represented by Anemone (33.3 %) and Ranunculus (20.8 %), Gentianaceae is strongly dominated by Gentiana (94.7 %), and Fabaceae is composed of Astragalus (33.3 %) and Oxytropis (27.8 %). Rosaceae consists of perennial herbs such as Argentina (33.3 %) and Potentilla (22.2 %) and dwarf shrub Dasiphora (11.1 %). Poaceae is dominated by tussock grasses, including Poa (17.6 %), Aristida (17.6 %), Stipa (11.8 %), and Festuca (11.8 %). The dominant grassland families are mainly distributed in the central and northern parts of the HDM-Plot study region (Fig. 6a). Asteraceae, Cyperaceae, Ranunculaceae, Rosaceae, and Poaceae are broadly recorded across grassland plots, whereas Gentianaceae and Fabaceae have relatively lower plot frequencies (Fig. 6a). Their elevational distributions are concentrated in high-elevation belts, but with slight differences in distribution centers and ranges (Fig. 6c). The dominant genera include Gentiana, Kobresia, Saussurea, Anaphalis, Artemisia, Anemone, and Carex (Table 2). Kobresia is the most broadly distributed dominant grassland genus across both horizontal space and the elevational gradient, consistent with its role as a major alpine meadow constructive genus (Fig. 6b, d). Gentiana, Saussurea, Anaphalis, Anemone, and Carex are also mainly concentrated in high-elevation grasslands, whereas Artemisia shows a relatively narrower and slightly lower elevational distribution compared with the other dominant genera (Fig. 6d).

The 1127 species in the HDM-Plot dataset can be categorized into five growth forms (Fig. 7a). Shrubs comprise the largest proportion of recorded species (46.0 %), followed by trees (27.3 %) and herbs (23.6 %), while climbers (2.0 %) and semi-shrubs (1.2 %) contribute a small number of species (Fig. 7a). Among herbs, perennials dominate (92.1 %), while annuals (6.0 %) and biennials (1.9 %) are comparatively rare (Fig. 7b). Woody species show clear contrasts in leaf type and phenology (Fig. 7b). Shrubs are almost composed of broadleaf (98.7 %), with deciduous shrubs (59.7 %) more frequent than evergreen shrubs (40.4 %), whereas trees exhibit a higher proportion of needleleaf species (11.7 %) and a near balance between evergreen (52.3 %) and deciduous (47.8 %) species (Fig. 7b).

In the HDM-Plot study region, plot-level species richness shows distinct elevational trends among vegetation types after accounting for plot area (Fig. 8a). Forest plots maintain relatively high species richness from low to middle elevations, followed by a decline toward higher elevations. Shrubland plots show a decreasing trend along the elevational gradient. Grassland plots are restricted to middle- and high-elevation belts, with relatively high richness at the lower part of their observed elevational range and a gradual decline toward higher elevations.

Growth-form composition varies clearly across elevational belts in surveyed plots (Fig. 8b). Trees dominate the lowest elevational belt and decline with increasing elevation. Shrubs remain the major component from low-middle to high elevations and are especially prominent in the middle-elevation belts. Herbs increase strongly toward the highest elevational belt. Woody life-form composition also shifts with elevation (Fig. 8c, d). For shrubs, deciduous broadleaf shrubs dominate most elevational belts, whereas evergreen broadleaf shrubs contribute substantially across the elevational gradient, particularly from low to middle elevations. Evergreen needleleaf shrubs are absent or rare at lower elevations and occur mainly in the upper elevational belts (Fig. 8c). Tree life forms show stronger elevational turnover (Fig. 8d). Evergreen broadleaf trees are more common at low elevations and decrease sharply toward higher elevations. Deciduous broadleaf trees contribute substantially from low to middle-high elevations but decline in the highest belt. Evergreen needleleaf trees increase with elevation and become dominant in the upper belts. Deciduous needleleaf trees are largely restricted to high-elevation belts (Fig. 8d).

At the family level, 117 families can be assigned to 10 areal-type categories (Fig. 9a). Cosmopolitan families account for 30.8 % of the total, tropical families for 39.3 %, and temperate families for 29.9 %. Pantropic families comprise the largest share within tropical families (63.0 %), with species-rich families including Lauraceae, Sapindaceae, Celastraceae, Euphorbiaceae, and Anacardiaceae. North temperate families account for 62.9 % of the temperate component, represented by Ericaceae, Fagaceae, Berberidaceae, Salicaceae, and Pinaceae. These patterns reflect that the floristic composition of the HDM-Plot study region retains tropical–subtropical elements while also incorporating temperate–alpine attributes.

At the genus level, 379 genera can be assigned into 15 areal-type categories (Fig. 9b). Temperate genera dominate (54.1 %), followed by tropical genera (35.4 %), whereas cosmopolitan (6.6 %) and Chinese endemic genera (4.0 %) are less frequent. Temperate genera are mainly north temperate (42.9 %), represented by Rhododendron, Berberis, Cotoneaster, Salix, and Quercus. For tropical genera, pantropical (32.8 %) and tropical Asian (28.4 %) areal-types are most common, with Ilex and Indigofera as pantropical representatives and Fargesia, Leptodermis, Caryopteris, and Corylopsis as East Asian representatives. Compared with the family level, the genus level composition shows a clear shift toward temperate elements. However, when the number of species contained in each areal-type group is considered, temperate genera account for 66.7 % of the recorded species, whereas tropical genera account for 23.3 % (Table S2). A plot–genus occurrence analysis further shows that temperate genera dominate plot-level occurrence records and are mainly associated with high elevations, whereas tropical genera are more closely associated with low elevations (Fig. S2). Both temperate and tropical genera are spatially widespread within the study region, but the number of plot-level occurrence records of temperate genera is nearly four times that of tropical genera (Fig. S2). Therefore, the dataset records transitional floristic features across the Hengduan Mountains and adjacent regions, while temperate elements remain dominant when species representation and plot-level occurrence are considered.

Based on field surveys and the revised vegetation classification system of China (Guo et al., 2020), 314 plots can be classified into three vegetation formation groups, namely forest, shrubland, and grassland (Fig. 10; Table S4). These plots can be further classified into 18 vegetation formations, 142 alliance groups, 209 alliances, 238 association groups, and 299 associations (Table S4). Because these lower-level units are highly detailed and many are represented by only one plot, the full hierarchical classification is provided in Table S4 and in the published dataset, whereas the main text focuses on vegetation formation groups and vegetation formations (Fig. 10; Table 3).

Forest vegetation formation group includes eight vegetation formations: deciduous needleleaf forest (DNF), mixed deciduous and evergreen needleleaf forest (DENF), evergreen needleleaf forest (ENF), mixed needleleaf and broadleaf forest (NBF), deciduous broadleaf forest (DBF), mixed evergreen and deciduous broadleaf forest (EDBF), evergreen broadleaf forest (EBF), and rainforest (RF) (Table S4). DNF includes only one alliance (Larix potaninii var. macrocarpa) and appears at 3732–4136 m in the central and northwestern study region. It has 10 ± 2 species per plot, community height of 10.5 ± 3.9 m, coverage of 71 ± 13 %, and mean DBH of 11.9 ± 5.1 cm. DENF is also rare and was recorded from a single plot in Fugong (western border between China and Myanmar) at 3247 m. This plot contains 4 species, community height of 15.6 m, coverage of 35 %, and mean DBH of 10.1 cm. ENF is widespread throughout the study region at 1809–4377 m and is constructed by Pinus, Abies, Picea, Juniperus, and Tsuga. It includes 12 ± 6 species per plot, community height of 16.7 ± 7.4 m, coverage of 66 ± 14 %, and mean DBH of 17.1 ± 11.6 cm. NBF is concentrated in the southern study region at 1801–4189 m and typically combines Pinus, Abies and Picea with broadleaf trees such as Quercus, Alnus, and Lithocarpus. This formation records 14 ± 7 species per plot, community height of 18.9 ± 6.4 m, coverage of 68 ± 17 %, and mean DBH of 16.1 ± 7.9 cm. DBF is widely distributed at 1256–4217 m, excluding the northwestern study region, and is commonly constructed by Alnus, Betula, Quercus, and Populus. The corresponding plot-level values are 14 ± 7 species per plot, 13.1 ± 5.5 m in community height, 76 ± 13 % in coverage, and 10.2 ± 5.8 cm in mean DBH. EDBF occurs patchily from the southwestern to northeastern study region at 966–3298 m, where evergreen components mainly Quercus and Castanopsis co-occur with deciduous broadleaf taxa such as Alnus. It has 15 ± 6 species per plot, community height of 14.8 ± 6.4 m, coverage of 73 ± 10 %, and mean DBH of 10.7 ± 5.5 cm. EBF is widespread at low to middle elevations (906–3636 m) in the study region and is most frequently constructed by Quercus. This formation surveys 12 ± 5 species per plot, 14.7 ± 8.8 m in community height, 74 ± 16 % in coverage, and 15.4 ± 8.8 cm in mean DBH. RF is restricted to the lowest elevations in Medog, northwestern part of the study region (754–1431 m) and is characterized by tropical and subtropical trees. RF plots contain 24 ± 7 species per plot, community height of 35.3 ± 11.9 m, coverage of 80 ± 10 %, and mean DBH of 23.3 ± 10.9 cm (Fig. 10; Table 3).

Shrubland vegetation formation group can be further divided into six vegetation formations: evergreen needleleaf shrubland (ENS), needleleaf and broadleaf shrubland (NBS), deciduous broadleaf shrubland (DBS), evergreen and deciduous broadleaf shrubland (EDBS), evergreen broadleaf shrubland (EBS), and bamboo shrubland (BS) (Table S4). ENS consists of two alliances (Juniperus squamata and J. convallium) and occurs mainly along the central and northwestern margin of the study region at 3757–4668 m. ENS plots have 5 ± 2 species per plot, community height of 2.5 ± 2.3 m, coverage of 78 ± 18 %, and mean BD of 3.4 ± 1.8 cm. NBS is rare and was surveyed from high-elevational area (4044–4720 m) in Chamdo, northwestern part of the study region, where Juniperus co-occurs with broadleaf shrubs including Ribes, Salix, and Spiraea. Its plot-level values are 6 ± 1 species per plot, 2.4 ± 1.0 m in community height, 60 ± 33 % in coverage, and 2.6 ± 1.6 cm in mean BD. DBS is widespread across the study region at 1772–4662 m and is most frequently dominated by Berberis, Salix, Rosa, Cotoneaster, and Sibiraea. This formation includes 7 ± 4 species per plot, community height of 2.7 ± 1.7 m, coverage of 61 ± 21 %, and mean BD of 1.6 ± 0.6 cm. EDBS spans a broad elevational gradient (1144–4226 m) from the central to northeastern study region and features mixtures of evergreen (e.g., Rhododendron and Daphne) with deciduous components (e.g., Rosa and Zanthoxylum). EDBS plots contain 10 ± 6 species per plot, community height of 3.6 ± 3.1 m, coverage of 62 ± 22 %, and mean BD of 1.9 ± 1.2 cm. EBS is widely distributed from the southwestern to northeastern study region at 1257–4758 m and is commonly dominated by Rhododendron and Quercus. It has 5 ± 4 species per plot, community height of 2.5 ± 2.3 m, coverage of 69 ± 17 %, and mean BD of 1.6 ± 1.1 cm. BS is uncommon in the dataset and was found in Yunnan Province at 3120–3290 m and includes two alliances (Fargesia gongshanensis and F. melanostachys). BS plots record 5 ± 4 species per plot, community height of 5.4 ± 2.9 m, coverage of 68 ± 11 %, and mean BD of 2.7 ± 1.1 cm (Fig. 10; Table 3).

Grassland vegetation formation group comprises four vegetation formations: tussock grassland (TG), rhizome grassland (RG), forb grassland (FG), and semi-shrub grassland (SSG) (Table S4). TG is widespread across the study region at 3168–4932 m and is strongly dominated by Kobresia, especially the widespread alpine meadow species K. pygmaea (24 plots). This formation has 12 ± 4 species per plot, community height of 0.061 ± 0.033 m, and coverage of 81 ± 15 %. RG occurs mainly in the northern study region at 3379–4701 m and is represented by Carex, with C. enervis frequently recorded. It contains 14 ± 5 species per plot, community height of 0.108 ± 0.102 m, and coverage of 79 ± 25 %. FG is concentrated from the central to northern study region at 3345–4784 m and is characterized by forb constructed communities, with Argentina as a common genus. Its plot-level values are 11 ± 6 species per plot, 0.079 ± 0.055 m in community height, and 77 ± 16 % in coverage. SSG is rare and has a single alliance (Artemisia vestita), observed in dry-hot valleys in the northwestern study region at 3186–3710 m. The alliance has 5 ± 3 species per plot, community height of 0.300 ± 0.283 m, and coverage of 50 ± 28 % (Fig. 10; Table 3).