Epiphytic Habit and Spatial Distribution Patterns of Phalaenopsis deliciosa and Phalaenopsis hainanensis
1
Key Laboratory of Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants (Ministry of Education), School of Tropical Agriculture and Forestry, Hainan University, Danzhou 571700, China
2
Sanya Institute of Breeding and Multiplication, Hainan University, Sanya 572025, China
*
Author to whom correspondence should be addressed.
Diversity 2025, 17(12), 818; https://doi.org/10.3390/d17120818
Submission received: 21 October 2025
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Revised: 19 November 2025
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Accepted: 24 November 2025
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Published: 27 November 2025
(This article belongs to the Section Plant Diversity)
Abstract
Epiphytic orchids are the largest group of epiphytes and are important components of forest species diversity. Epiphytic orchids show host preferences. Their spatial distribution is shaped by microhabitat preferences, host tree characteristics, and mycorrhizal associations. In this study, the habitat community structure and epiphytic habits of epiphytic orchids, Phalaenopsis deliciosa and Phalaenopsis hainanensis, distributed on Hainan Island were investigated. The results show that the vascular plant genera in the communities of P. deliciosa and P. hainanensis are characterized by biogeographical affinities dominated by tropical Asian and pantropical elements, accounting for 30.60% and 21.64% in the P. deliciosa community and 26.42% and 24.53% in the P. hainanensis community, respectively. Within the surveyed plots of this study, 41 epiphytic host species were recorded for P. deliciosa and 17 for P. hainanensis. Both P. deliciosa and P. hainanensis showed a high epiphytic preference for Streblus ilicifolius, with selectivity index values of 21.89 and 26.00, respectively. Both P. deliciosa and P. hainanensis exhibited clear small-scale aggregated horizontal distributions, with the O-ring analysis indicating statistically significant clustering (p < 0.05). Specifically, P. hainanensis showed aggregation within the 0.25–0.75 m range, whereas P. deliciosa displayed aggregation at radii of 0.25–2.25 m. In the vertical distribution, individuals of P. deliciosa occurred below 5 m and were concentrated at heights of 1–1.9 m. Individuals of P. hainanensis were distributed below 4 m, with no significant differences among height classes, although the highest abundances occurred at heights of 0–0.9 m and 2–2.9 m. Heights of 0–0.9 m and 2–2.9 m were the most abundant. In summary, individuals of both Phalaenopsis species were predominantly distributed at lower height ranges. The protection of the habitat plant community, especially the preferred epiphytic tree species or companion plants, should be strengthened to conserve the Phalaenopsis species.
1. Introduction
Epiphytes are significant and characteristic components of tropical rain forests. They play an important role in maintaining forest species diversity and ecosystem functions, such as carbon sequestration, water, and nutrient cycling [1]. Approximately 7.5% of vascular plants are epiphytes [2,3], and most epiphytic species belong to 876 genera across 84 families [4]. Orchidaceae plants are widely distributed in various terrestrial ecosystems except for polar and extremely arid regions and are one of the most evolved and advanced groups in plants. The morphological and physiological characteristics of most orchids are particularly suitable for existing as epiphytes and using other plants as hosts, making them the most species-rich group of epiphytes. Approximately 70% of orchid species are epiphytes, making Orchidaceae one of the most species-rich groups within epiphytic plants, and most of them occur in humid tropical regions with exceptionally high diversity [5,6]. In Orchidaceae, the number of epiphytic species generally exceeds the number of terrestrial species in many genera [7]. The epiphytic Orchidaceae have higher rates of speciation and diversification than terrestrial orchids [8]. The epiphytic habit is a significant evolutionary characteristic of orchids, affecting the survival, formation, proliferation, and differentiation of orchid species. However, some epiphytic orchids exhibit relatively slow growth due to ecological specialization and are highly sensitive to microhabitat conditions in areas where habitat degradation and human disturbance are pronounced, the wild populations of certain epiphytic orchid species may be at risk [9,10].
Although the vascular structures of epiphytes and their host plants are independent, some epiphyte orchids show preferences for their host selection [4]. This epiphytic preference is influenced by multiple factors, including microenvironmental conditions [11], the physicochemical properties of host bark [12], and the spatial availability of symbiotic fungi [13]. Previous studies indicate that the heterogeneous distribution of orchid mycorrhizal fungi can affect seedling establishment sites, providing a potential ecological link to the spatial distribution patterns observed in epiphytic orchids. Such below-ground or substrate-level fungal enrichment may contribute to the small-scale aggregated distribution observed in mature individuals [14]. Many studies have shown that the formation process of the spatial distribution pattern of plant populations in nature is complex. It is also affected by a variety of abiotic and biotic factors such as environmental factors, human disturbance, animal transmission capacity, and interspecific competition. Studying the spatial distribution pattern of plant populations allows understanding the biological characteristics of plant populations, the interaction between these populations, and the relationship between populations and the environment [15]. The regeneration strategy of plant populations based on changes in the spatial distribution pattern could be obtained. Investigating the spatial distribution of the orchids is of great significance for exploring the formation and maintenance mechanisms of the plant community and its biodiversity.
Due to their exceptionally high ornamental value, many wild Phalaenopsis populations from tropical Southeast Asia to Hainan Island have been subjected to substantial pressure from over-collection and habitat loss in recent decades [16]. On Hainan Island, only three Phalaenopsis species have been documented: the lithophytic Phalaenopsis pulcherrima and the epiphytic Phalaenopsis deliciosa and Phalaenopsis hainanensis [17,18]. This ecological distinction is meaningful for our research because lithophytic and epiphytic orchids differ fundamentally in substrate dependence and microhabitat requirements, which necessitates analyzing their spatial patterns and habitat associations separately within the study design.
In this study, the composition of the habitat plant communities of P. deliciosa and P. hainanensis were studied by setting up transects or quadrants in the Bawangling area of Hainan. The community floristic characteristics, epiphytic characteristics, and spatial distributions of P. deliciosa and P. hainanensis were investigated. The results of this study provide insight into the epiphytic habit, the structure of the orchid community in the habitats, population distribution, and ecological functions of P. deliciosa and P. hainanensis, and may be utilized to develop strategies for the conservation of orchids. Therefore, the objectives of this study were to (1) analyze the community structure and floristic composition of the habitats of P. deliciosa and P. hainanensis; (2) evaluate their epiphytic host preferences; (3) characterize their horizontal and vertical spatial distribution patterns to provide insights into their adaptive strategies and conservation.
2. Materials and Methods
2.1. Materials
The Bawangling Branch of Hainan Tropical Rainforest National Park is located in the southwest of Hainan Island (18°53′–19°20′ N, 108°58′–109°53′ E) (Figure 1). In this study, three natural populations of P. deliciosa and two natural populations of P. hainanensis were investigated. Transects and quadrants were established according to the terrain and species distribution. The total areas of the transects and quadrats were 1550 m2 and 900 m2, respectively (Table 1, Figure 2). P. deliciosa, epiphytes growing on tree trunks or valley rocks in montane forests at an altitude of 100–1100 m, are widely distributed as far west as southern India and Sri Lanka, as far north as the tropical Himalayas and Yunnan, China, as far south as Indonesia, and as far east as the Philippines, which are in the tropical and subtropical regions of Asia [19]. P. deliciosa are distributed in Ledong, Changjiang, Sanya, and other places on Hainan Island, China. P. hainanensis, epiphytes growing on tree trunks or subterranean-forest rocks in mountain forests at an altitude of 600–1300 m, are commonly found in limestone areas, and distributed in Ledong, Baisha, Changjiang, and other places on Hainan Island, China [19]. Field sampling within Hainan Tropical Rainforest National Park is subject to strict conservation regulations. Large portions of the known distribution ranges of P. deliciosa and P. hainanensis fall within core protection zones where researcher access is prohibited. The accessible areas are confined to steep river valleys and fragmented limestone slopes, which substantially limit the number, size, and spatial arrangement of quadrats that can be safely and legally established. Consequently, all sampling sites used in this study represent the full extent of confirmed and accessible natural populations under current park restrictions.
2.2. Data Processing and Analysis
2.2.1. Plant Community Structure
Plant community structure refers to the spatial arrangement and quantitative relationships among species within a community, typically described using metrics such as frequency, coverage, and dominance.
In this study, community structure was quantified through the following indices:
Frequency = the number of quadrats in which a particular plant species is found/the total number of quadrats surveyed. Coverage = (vertical projected area of the aerial part of the plants of a certain species/quadrats area) × 100%.
Abundance = the number of plants of a certain species in a plot.
Relative frequency (RF) = (frequency of a certain species/sum of frequencies of all species) × 100%.
Relative coverage (RD) = (coverage of a certain species/total coverage of all species of the plot) ×100%.
Relative abundance (RA) = (the number of plants of a certain species in the plot/the total number of plants of this species in all surveyed plot) × 100%.
The importance values were calculated according to the following equation [15,21]: IM = (RF + RD + RA)/3, where IM stands for importance value; RF is the relative frequency; RD is the relative coverage; RA is the relative abundance. The larger the IM value is, the higher the dominance of the species in the community. The relative tree coverage is calculated by using the projected area of the tree canopy over the total area; the relative coverage of the shrub layer is calculated by using the projected area of the shrub layer over the total area [22]. The herbaceous layers of the two species had fewer plant species, and no statistical calculations were performed. As importance values are compositional indices derived from frequency, coverage, and abundance, they are not subjected to statistical significance testing or confidence interval estimation; instead, they are used descriptively to compare the relative dominance of species within communities.
The areal type distribution of the seed plant families was identified according to the method published by Zhengyi Wu (2011) [23].
2.2.2. The Eepiphytic Selectivity Index
According to the equation reported in the literature by Xiqiang Song (2005) [24], the epiphytic selectivity index Esi was calculated to evaluate the selection preference and dependence of epiphytic plants on the host tree.
The epiphytic index (Esi) is determined by using 1/3 of the sum of the relative abundance (RA), the relative prominence (RP), and the relative frequency (RF).
In this study, abundance refers specifically to the number of host-tree individuals that support the focal epiphytic species; frequency corresponds to the proportion of individuals of a given host-tree species that bear the focal epiphyte; and prominence denotes the total number of epiphytic individuals occurring on each host-tree species. Relative abundance RHA, relative frequency RHF, and relative prominence RHP were calculated accordingly.
Relative abundance of host trees (RHA), relative frequency (RHF), and relative prominence (RHP) were defined as follows:
RHA was calculated as the number of individuals of a given host tree species that carry the focal epiphyte divided by the total number of host trees supporting epiphytes in that community × 100%.
RHF was defined as the frequency of epiphytes occurring on a given host tree species divided by the sum of epiphyte frequencies on all host trees in the community × 100%.
RHP represented the total number of individuals of the focal epiphyte found on a given host tree species divided by the total number of individuals of the epiphyte recorded on all hosts in the community × 100%.
Excel 2016 was used for data processing and analysis.
2.2.3. Horizontal Spatial Distribution Pattern
The spatial distribution pattern and related analyses were conducted using PROGRAMITA version 1.0 [25]. The non-cumulative univariate O-ring O(r) statistic [25] used to analyze the spatial distribution pattern of individuals in the population. The coordinates of the host tree species were used as the distribution focal points. The initial scanning radius to the focal point was set to 0.25 m, and the radius was gradually increased with a step size of 0.25 m., respectively; the maximum values of r for the 9 quadrants containing P. hainanensis were all set to 5 m. To avoid errors caused by the small number of samples, only the quadrant with 10 or more individuals (P1, P4, P5, and P6) were statistically analyzed [26,27,28]. A Monte Carlo simulation was performed 999 times, using those individuals in the population that conformed to the Complete Spatial Randomness (CSR) as the null hypothesis. The lowest and highest values of the 25th simulation were used to determine the 95% confidence interval (CI). When O(r) is higher than the maximum value of the confidence interval, the distribution is an aggregated distribution; if O(r) is within the confidence interval, the distribution is a random distribution; if O(r) is lower than the minimum of the confidence interval, the distribution is a uniform distribution. The statistical results also give the first-order intensity (λ) of the spatial point distribution pattern [28] slope bLO(r) and the 95% confidence interval (95% CI) were obtained by linear regression of the O(r) and ln(r) of each population using the SPSS 22.0 software; the regression slopes of different populations were also compared. The ORIGIN 2020 (9.7) software was used to generate the 3D spatial distribution graphs.
2.2.4. Vertical Spatial Distribution Pattern
The unit epiphytic surveying height of each host plant was set to 1 m, and the distribution frequency of individuals of the epiphytes in each height unit was analyzed. Each transect or quadratic unit was analyzed for significant differences in the distribution frequency in the different height units and the vertical distribution characteristics of P. deliciosa and P. hainanensis were obtained. Significant difference analysis was performed using SPSS 22.0 software.
3. Results
3.1. Community Structure Composition
3.1.1. Habitat Community Composition of P. deliciosa
In the 3 surveyed transects of P. deliciosa (1550 m2 in total), there are 159 species of vascular plants in 53 families, 134 genera, including 2 families, 2 genera, and 2 species of ferns (Table A1). Among the recorded taxa, 22 families are monotypic, accounting for 41.51% of all families, and 116 genera are monotypic, representing 72.96% of all genera. This indicates a highly ‘monotypic’ taxonomic structure within the community, suggesting substantial phylogenetic dispersion and floristic heterogeneity. Within the P. deliciosa community, families and genera show a dispersed taxonomic composition. The most species-rich families include Euphorbiaceae (20 species, 12.58% of all species), Rubiaceae (15 species, 9.43%), Lauraceae (10 species, 6.29%), and Annonaceae (9 species, 5.66%), representing the major contributors to the floristic assemblage of this habitat.
The habitat community of P. deliciosa exhibited a high level of species diversity, with a Shannon–Wiener index of H′ = 3.53 and a Simpson index of 1 − D = 0.96, indicating a structurally complex community with rich species composition. Similarly, the habitat community of P. hainanensis also showed a high degree of species diversity, with a Shannon–Wiener index of H′ = 3.17 and a Simpson index of 1 − D = 0.94, reflecting a well-structured community with considerable species richness.
A total of 72 plant species were counted in the tree layer of the YJ population, among which Streblus taxoides, Erismanthus sinensis, Streblus ilicifolius, and Hydnocarpus hainanensis had high importance values (>5%), and were the dominant species in the plant community of this population (Table 2). A total of 65 plant species was counted in the tree layer of the ED population, among which Mallotus peltatus and E. sinensis were the dominant species in the plant community of this population. A total of 42 plant species were counted in the tree layer of the SD population, where S. ilicifolius, Terminalia hainanensis, Dasymaschalon trichophorum, and Cleistanthus concinnus had an importance value of >5% and were the dominant species in the plant community of this population. Overall, S. ilicifolius, S. taxoides, and T. hainanensis were the dominant species in the tree layer of the community where P. deliciosa resided (Table 2).
A total of 48 plant species were counted in the shrub layer of the YJ population, among which Schizostachyum pseudolima, S. ilicifolius, S. taxoides, and D. trichophorum were the dominant species in the plant community of this population (Table 3); a total of 32 plant species were counted in the shrub layer of the ED population, among which S. pseudolima and Licuala fordiana were the dominant species in the plant community of this population (Table 3); a total of 11 plant species were counted in the shrub layer of the SD population. S. ilicifolius, S. taxoides, T. hainanensis, D. trichophorum, C. concinnus, and Actephila merrilliana showed high important values (>5%) and were the dominant species of the plant community of this population (Table 3). Overall, Schizostachyum pseudolima, D. trichophorum, S. taxoides, S. ilicifolius, and Actephila merrilliana were the dominant species in the shrub layer of the community where P. deliciosa resided (Table 3).
3.1.2. The Composition of the Plant Community in P. hainanensis Plots
Across the two surveyed sites (Appendix B), nine 10 m × 10 m plots (totaling 1000 m2) contained 61 vascular plant species belonging to 53 genera and 34 families. These included 25 monotypic families (73.53% of all families) and 46 monotypic genera (86.79% of all genera), indicating a highly dispersed taxonomic composition. Among these taxa, Euphorbiaceae (5 species, 8.20%), Orchidaceae (8 species, 13.11%), and Oleaceae (3 species, 4.92%) represented the families with relatively higher species richness within the community. These patterns suggest substantial taxonomic richness and phylogenetic differentiation in the surveyed habitat.
A total of 26 plant species were counted in the tree layer of the EXL population, among which Quercus bawanglingensis, S. ilicifolius, Mallotus yunnanensis, Sterculia lanceolata, Aglaia odorata var. microphyllina, and Osmanthus matsumuranus were the dominant species in the plant community of this population (Table 4); a total of 31 plant species were counted in the tree layer of the YZC population. The species with important values higher than 5% include S. ilicifolius, Clausena excavate, and Dehaasia hainanensis. Overall, S. ilicifolius, Mallotus yunnanensis, Dehaasia hainanensis, Clausena excavata, Quercus bawanglingensis, and Sterculia lanceolata were the dominant species in the tree layer of the P. hainanensis community (Table 4). A total of 8 plant species were counted in the shrub layer of the EXL population. M. yunnanensis and Croton cascarilloides with a high importance value (>5%) were the dominant species in the plant community of this population (Table 2, Table 3, Table 4 and Table 5). A total of only 2 plants were counted in the shrub layer of the YZC population, Schefflera arboricola and Paramichelia baillonii. Overall, M. yunnanensis, Croton cascarilloides, Schefflera arboricol, and Paramichelia baillonii were the dominant species in the shrub layer of the P. hainanensis community (Table 5).
3.2. Community Floristic Characteristics
The vascular plants of the 134 genera in the community of P. deliciosa are mainly distributed in tropical Asia, with 41 genera, accounting for 30.60% of the total genera, followed by pantropical distributions with 29 genera, accounting for 21.64%. Tropical Asia to tropical Oceania with 21 genera, Old World tropical distribution with 18 genera, and tropical Asia to tropical Africa with 13 genera account for 15.67%, 13.43%, and 9.70%, respectively, while other flora types are less distributed (Table 6). The 53 genera of vascular plants in the community of P. hainanensis were dominated by pantropical distributions, with 14 genera accounting for 26.42%, followed by 10 genera in tropical Asia, accounting for 20.53%. The distribution of tropical Asia to tropical Oceania with 8 genera, north temperate zone with 5 genera, and Old World tropical distribution with 4 genera accounted for 15.09%, 9.43%, and 7.55%, respectively, while other flora types were less distributed (Table 6).
3.3. Epiphytic Habits
In this study, we found that the epiphytic hosts of wild P. deliciosa belonged to 24 families, 40 genera, and 41 species, among which the number of epiphytes of S. taxoides and S. ilicifolius of Moraceae family was the largest, accounting for 50.37% of the total epiphytes, followed by the number of epiphytes of M. peltatus and E. sinensis of the Euphorbiaceae family, and Sphenodesme pentandra of the Verbenaceae family (Table 7). The epiphytic index Esi of the host plant species studied was in the range of 0.43–21.89, among which only 4 species’ indexes were greater than 5.00, namely S. ilicifolius, S. taxoides, M. peltatus, and A. E. sinensis (Table 8). The epiphytic index Esi of S. ilicifolius is the largest, with values up to 21.89, followed by S. taxoides, which is 17.97; the number of epiphytic P. deliciosa was also the largest of these two host species, with 82 and 55 individual epiphytes, respectively, accounting for 30.15% and 20.22% of the total (Table 8). This indicated that P. deliciosa showed a high epiphytic preference for these two plant species.
The epiphytic hosts of P. hainanensis belong to 11 families, 15 genera and 17 species, among which S. ilicifolius of the Moraceae family and M. yunnanensis of the Euphorbiaceae family are epiphytes, with the highest number of epiphytes among these two host species, accounting for 41.30% and 19.57% of the total epiphytes, respectively. The number of other tree species hosting the epiphytic P. hainanensis was lower (Table 8). The variation range of the epiphytic index Esi of the host species studied was 2.58–26, of which the indexes of only 5 species were greater than 5.00, namely, S. ilicifolius, M. yunnanensis, S. lanceolata, Vietnam Ulmus tonkinensis, and C. excavata (Table 2, Table 3, Table 4, Table 5, Table 6, Table 7, Table 8 and Table 9). The epiphytic index Esi of S. ilicifolius was the highest, reaching 26.00, followed by M. yunnanensis, which was 17.98. The number of epiphytic P. hainanensis of S. ilicifolius and M. yunnanensis was also the largest, with 19 and 9 different epiphytes, respectively, accounting for 41.30% and 19.57% of the total epiphytes, respectively (Table 9). The results show that P. hainanensis has a very high epiphytic preference for these two plants.
3.4. Spatial Distribution Pattern
The spatial distribution of individuals of P. deliciosa showed the characteristics of aggregated distributions on a small scale within the three populations (Figure 3). The results of the non-cumulative univariate O-ring O(r) statistic analysis of the horizontal spatial distribution showed that the individuals of P. deliciosa within the populations had significant aggregated distribution characteristics in small-scale space (Figure 4A), and the SD populations were at radii of r = 0.25, 0.5 and 1–2 m; ED populations were at radii of r = 0.25, 0.5, 1–1.5 and 2–2.5 m; YJ populations were at radii of r = 0.25–1.5, 2, 3, 4, 4.5 and 5 m (Figure 4A); SD, ED, and YJ populations aggregated the most at radii of 0.25, 0.25 and 0.5 m, respectively. The bLO(r) values of the three populations were all significantly less than 0 (p < 0.05). The SD population had the highest bLO(r) at −0.171 (95% CI: −0.294, −0.048). The bLO(r) of the ED population was −0.028 (95% CI: −0.051, −0.005), and the bLO(r) of the YJ population was −0.014 (95% CI: −0.005): −0.024, −0.004). The bLO(r) value of the SD population was not significantly different from that of the ED population but was significantly different from that of the YJ population. The individual dot pattern intensity (λ) was the highest in YJ, reaching 0.0160, with SD and ED of 0.0138 and 0.0080, respectively (Figure 4A). In terms of vertical spatial distribution, the individuals of the SD and ED populations were both distributed below 4 m with most individuals distributed at 1–1.9 m (Figure 4B). In general, the vertical spatial distribution of the individuals in the three populations is mainly concentrated below 4 m, with 1–1.9 m being the largest in number and frequency (Figure 5A,B); The distribution frequency of individuals at 0–1 m and 1–1.9 m was significantly higher than that of other height ranges (p < 0.05) (Figure 5B).
The spatial distribution of individuals of P. hainanensis showed the characteristics of aggregated distributions on a small scale in 9 quadrats (Figure 6). In terms of the horizontal spatial distribution pattern, the O-ring statistic analysis results of the P1, P4, P5, and P6 quadrats with more than 10 individuals each showed significant aggregated distribution for P. hainanensis individuals in the quadrats in the small-scale space (Figure 7). The P1 quadrat was at a radius of r = 0.25–2.25 m; the P4 quadrat was at 0.25–0.75 m; the P5 quadrat was at radii of 0.25, 2.25, and 2.5 m; the P6 quadrat was at radii of 0.25, 0.75, 1.75, and 2.5 m (Figure 7). The P1 quadrat had the highest aggregation intensity at 0.5 m, and the P4, P5, and P6 quadrat had the highest aggregation intensity at 0.25 m. The bLO(r) values of the four quadrats were all significantly less than 0 (p < 0.05). The highest bLO(r) for the P1 quadrat was −0.171 (95% CI: −0.294, −0.048); −0.028 (95% CI: −0.051, −0.005) for the ED population and −0.014 (95% CI: −0.024, −0.004) for the YJ population. The bLO(r) of the SD population was not significantly different from that of the ED population, but was significantly different from that of the YJ population (p < 0.05). The individual point pattern intensity (λ) was the highest in the P5 quadrat, reaching 0.0250; the intensities for P3, P2, and P6 were 0.015, 0.013, and 0.012, respectively (Figure 7). In terms of vertical spatial distribution, the distribution heights of individuals within the 9 quadrats were different for each distance class (Table 9). Only the individuals in the P1 quadrat were represented in each vertical distance class studied; the individuals in the P5, P6, and P7 were distributed in only one distance class, which was 0–0.9, 2–2.9, and 0–0.9 m, respectively (Table 9). Overall, the 0–0.9 m and 2–2.9 m vertical distance classes had the largest number of individuals, but there was no significant difference in the 1–1.9 and 3–4 m vertical distance classes (Table 9).
4. Discussion
4.1. Plant Community Structure and Floristic Characteristics
Epiphytes are strongly influenced by the microclimate of the forest canopy, and understanding its plant community structure and zonation characteristics can reflect to some extent the ability of the epiphyte to adapt to the environmental climate [29]. In this study, the community differences associated with P. deliciosa and P. hainanensis—such as distinct structural composition and dominant taxa—provide ecological context for understanding how these epiphytic orchids adapt to contrasting microclimatic environments. The habitat communities of both P. deliciosa and P. hainanensis exhibit high species diversity, with Shannon–Wiener indices of H′ = 3.53 and H′ ≈ 3.17 and Simpson indices of 1 − D = 0.96 and 1 − D ≈ 0.94, respectively. Their family- and genus-level compositions are also relatively dispersed, with high proportions of monotypic families and genera, indicating structurally complex communities with considerable phylogenetic differentiation. A total of 159 species of 53 families, 134 genera, and 159 species of vascular plants were counted in the 3 sample plots of P. deliciosa, while a total of 61 species of 34 families, 53 genera, and 61 species of vascular plants were counted in the 2 sample plots of P. hainanensis. Within the surveyed plots of this study, the plant communities associated with P. deliciosa and P. hainanensis showed certain compositional similarities, including overlap in dominant families and comparable structural characteristics. For example, both communities were primarily composed of taxa such as Euphorbiaceae. The most dominant family for both Phalaenopsis is Euphorbiaceae. Rubiaceae and Orchidaceae, commonly found in tropical regions, are also an important part of the two epiphytic orchid communities, reflecting the tropical nature of the community. The 134 genera of P. deliciosa and 53 genera of P. hainanensis have typical tropical characteristics, with the tropical components (2–7 flora types) of P. deliciosa and P. hainanensis accounting for 95.52% and 77.36%, respectively.
4.2. Epiphytic Habit
Epiphytes have a very high species diversity, accounting for about 7.5% of extant vascular plants [2,3]. They are a class of vascular plants that germinate non-parasitically on other plants and depend on the structural support of other plants in all stages of life. Epiphytic plants represent one of the most prominent and diverse life forms in tropical forest canopies, contributing substantially to canopy structure and ecosystem functioning [30]. Epiphytes often suffer from intermittent water scarcity due to lack of access to soil water, and water availability is often the most limiting factor for epiphytes. For this reason, epiphytic vascular plants have developed a series of epiphytic-related traits such as a water reservoir, succulent leaves, succulent stems, and a crassulacean acid metabolism (CAM) cycle [4,31]. The evolution of epiphytic traits has prompted independence and rapid diversification of some plant families, such as Orchidaceae, Bromeliaceae, and Leptosporangiopsida, among which Orchidaceae account for two-thirds of all epiphyte species [7,32].
The epiphytic habit is an extremely important evolutionary characteristic of orchids [7,8]. It affects the survival, formation, proliferation, and differentiation of orchids, and also promotes the formation of species diversity of orchids. More than 70% of orchid species are epiphytic and most species are distributed in tropical regions [5]. Epiphytes usually show a preference for host trees, but rarely a strictly exclusive preference for a particular host tree [21].
A total of 41 epiphytic hosts of P. deliciosa in this study showed that their host trees had strong adaptability; S. taxoides and S. ilicifolius had the largest number of epiphytes. There are a total of 17 epiphytic hosts of P. hainanensis, among which S. ilicifolius and M. yunnanensis have the most epiphytes. The preferred tree species of the two kinds of Phalaenopsis epiphytes are shrubs. Although the distribution altitudes are quite different, both P. deliciosa and P. hainanensis show epiphytic preference for the drought-tolerant S. ilicifolius. This might be because the distribution areas of the two Phalaenopsis belong to habitats with high light intensity and thermal resources but low humidity. These figures represent the host plants documented within the accessible sampling areas of each species rather than a standardized comparison of host diversity. In both cases, the highest numbers of epiphytes occurred on S. ilicifolius and other shrub-dominated hosts, reflecting the structural characteristics of the habitats surveyed. The dominance of both Phalaenopsis using S. ilicifolius as host might also be affected by the physical and chemical properties of S. ilicifolius bark and the presence of fungi.
Most epiphytic orchids like tall trees as their epiphytic hosts. These trees, as host or umbrella species for epiphytes, provide a relatively large attaching area to protect the epiphyte population and provide a relatively stable environment, such as sufficient light, water, and heat for the epiphytes [21]. In general, epiphytic orchid plants are widely distributed in the canopy layer, which may be related to the diverse micro-environment of the canopy layer, where the lateral branches extend horizontally, providing a suitable microclimate in the canopy. Seeds and seedlings attach easier to branches and horizontal branches, and the presence of a large amount of moss and humus is also conducive to seed attachment and germination. However, the two kinds of Phalaenopsis in this study resided in a very dry habitat with small branches and trunks. In this habitat, there are significantly fewer types of competing epiphytes; therefore, the two Phalaenopsis secure their ecological niche. This may be due to the fact that Phalaenopsis plants have developed a special drought-resistant mechanism in the evolutionary process to combat harsh habitats. The root system of P. deliciosa and P. hainanensis can extend more than 2 m along the main trunk of the epiphyte host, retaining water and nutrients to a greater extent.
4.3. Spatial Distribution
Orchid seed and pollen movement exhibit patterns distinct from most other angiosperms. Although orchids produce extremely small, “dust-like” seeds capable of being lifted by wind over long distances [33], numerous studies have shown that effective seed flow is often highly restricted. This is largely because orchid seeds lack endosperm and rely entirely on compatible mycorrhizal fungi for germination and early growth [34]. The distribution of these fungi is typically patchy, forming localized “hotspots” around adult plants, which increases the probability that seeds germinate in close proximity to maternal individuals [35]. In addition to fungal-driven microsite recruitment, several other well-documented processes—such as limited realized seed dispersal despite potential long-distance transport [36], spatial heterogeneity in suitable bark microhabitats for attachment and moisture retention [37], and historical patterns of establishment—may jointly contribute to the small-scale aggregation patterns observed in both P. deliciosa and P. hainanensis.
The individuals in the three populations of P. deliciosa all aggregated on a small scale in the horizontal distribution pattern. The vertical distribution pattern is below 5 m and concentrated within a distance range of 1–1.9 m. The individuals in the 9 quadrats of P. hainanensis also had aggregated distributions on the small scale in the horizontal distribution. The vertical distribution pattern appeared below 4 m, without any significant difference in the number of distributions in the different distance classes; the highest number of individuals were distributed at heights of 0–0.9 m and 2–2.9 m. The three-dimensional spatial distribution shows that both P. deliciosa and P. hainanensis exhibit a type of aggregation distribution on a small scale, by aggregating on the same host tree or adjacent host trees.
Orchids are mycorrhizal fungi-dependent plants, and the colonization of adult individuals is often also an area enriched with mycorrhizal fungi [33]. Therefore, most of the orchid seed germination and seedling renewal occur within a short distance from the adult individual, sometimes even only a few meters away [38]. The seed germination rate also decreases with increasing distance from the adult individual. Our results also indicate that the occurrence of this aggregation phenomenon may be related to the distribution of mycorrhizal fungi.
The spatial distribution pattern of epiphytic orchids varies with vegetation types. Gravendeel et al. (2004) [7] reported that the environmental factors of the epiphytic microhabitat and the characteristics of the host tree determine the distribution pattern of epiphytes on the host tree to a large extent. In this study, the vertical distribution heights of the two Phalaenopsis species were both low. This may be related to the preference for specific epiphytic tree species. The preferred epiphytic tree species of P. deliciosa and P. hainanensis are shrubs, with low growth height, also resulting in low epiphytic heights of the vertical spatial distributions.
5. Conclusions
Orchidaceae plants are widely distributed in various terrestrial ecosystems except for polar and desert regions. They are one of the most evolved and advanced plants. There are more than 800 genera and about 30,000 species. Orchids are important indicator species in tropical rainforests. Nearly 80% of orchid species are distributed in tropical rainforests, and 70% of them are epiphytes. The biological characteristics of orchids themselves make them extremely demanding on their habitats. Habitat decline and human collection often result in devastating damage to orchid populations, leading to the gradual degradation or disappearance of many wild orchid populations. Half (about 56.5%) of orchids, including vulnerable, endangered, or critically endangered species, are facing extinction.
To better contextualize our findings within the broader literature on epiphytic orchid ecology, it is important to consider whether the strong host selectivity and small-scale spatial aggregation observed in this study align with established ecological patterns. Previous research on epiphytic orchids has primarily focused on canopy-dwelling species in mature tropical rainforests, while species inhabiting secondary forests, forest margins, degraded habitats, or environmentally harsh substrates have received far less attention. Our results show that both P. deliciosa and P. hainanensis exhibit pronounced host preferences and clear micro-scale aggregation, patterns that are consistent with reports from other epiphytic orchids that rely heavily on microhabitat filtering, bark traits, and localized mycorrhizal availability. At the same time, the ability of these two species to persist in disturbed or suboptimal habitats highlights their exceptionally high stress tolerance, suggesting that their ecological strategies may differ from typical canopy-dependent epiphytes. These findings provide valuable insights into habitat adaptability, potential dispersal mechanisms, and community assembly processes under changing forest environments. They also underscore the importance of conserving orchid populations in secondary forests and degraded landscapes—areas that have historically been overlooked yet hold key evolutionary and conservation significance for the genus Phalaenopsis.
Author Contributions
Conceptualization, H.Z. and W.L.; methodology, W.L.; software, H.Z.; validation, W.L., H.Z. and Z.C.; formal analysis, W.L.; investigation, W.L.; resources, W.L.; data curation, W.L.; writing—original draft preparation, H.Z.; writing—review and editing, H.Z.; visualization, W.L., H.Z. and Z.C.; supervision, Z.Z.; project administration, Z.Z.; funding acquisition, Z.Z. All authors have read and agreed to the published version of the manuscript.
Funding
This research was supported by Natural Science Foundation (No. 32201347) and Hainan Natural Science Foundation No. 322RC569.
Data Availability Statement
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author(s).
Conflicts of Interest
The authors declare no conflicts of interest. The sponsors had no role in the design, execution, interpretation, or writing of the study.
Appendix A
Table A1.
The species list of Phalaenopsis deliciosa community.
| Family | Genus | Species |
|---|---|---|
| Liliaceae | Dracaena | Dracaena angustifolia |
| Dracaena cambodiana | ||
| Flacourtiaceae | Scolopia | Scolopia saeva |
| Hydnocarpus | Hydnocarpus hainanensis | |
| Homalium | Homalium hainanense | |
| Euphorbiaceae | Croton | Croton laevigatus |
| Koilodepas | Koilodepas hainanense | |
| Suregada | Suregada glomerulata | |
| Cleistanthus | Cleistanthus concinnus | |
| Drypetes | Drypetes hainanensis | |
| Drypetes indica | ||
| Drypetes perreticulata | ||
| Breynia | Breynia fruticosa | |
| Baccaurea | Baccaurea ramiflora | |
| Bischofia | Bischofia javanica | |
| Alchornea | Alchornea rugosa | |
| Sapium | Sapium insigne | |
| Antidesma | Antidesma hainanense | |
| Bridelia balansae | ||
| Actephila | Actephila merrilliana | |
| Mallotus | Mallotus hookerianus | |
| Mallotus peltatus | ||
| Mallotus yunnanensis | ||
| Aporusa | Aporusa dioica | |
| Erismanthus | Erismanthus sinensis | |
| Fabaceae | Ormosia | Ormosia semicastrata |
| Dalbergia | Dalbergia peishaensis | |
| Dalbergia tsoi | ||
| Dalbergia odorifera | ||
| Bowringia | Bowringia callicarpa | |
| Millettia | Millettia tsui | |
| Derris | Derris trifoliata | |
| Annonaceae | Polyalthia | Polyalthia laui |
| Fissistigma | Fissistigma oldhamii | |
| Fissistigma polyanthum | ||
| Desmos | Desmos chinensis | |
| Alphonsea | Alphonsea mollis | |
| Mitrephora | Mitrephora thorelii | |
| Artabotrys | Artabotrys hainanensis | |
| Dasymaschalon | Dasymaschalon trichophorum | |
| Uvaria | Uvaria macclurei | |
| Menispermaceae | Diploclisia | Diploclisia glaucescens |
| Burseraceae | Canarium | Canarium album |
| Ancistrocladaceae | Ancistrocladus | Ancistrocladus tectorius |
| Mimosaceae | Albizia | Albizia corniculata |
| Albizia odoratissima | ||
| Acacia | Acacia pennata | |
| Gramineae | Schizostachyum | Schizostachyum pseudolima |
| Apocynaceae | Wrightia | Wrightia pubescens |
| Ervatamia | Ervatamia hainanensis | |
| Alyxia | Alyxia sinensis | |
| Hunteria | Hunteria zeylanica | |
| Violaceae | Rinorea | Rinorea bengalensis |
| Malvaceae | Pterospermum | Pterospermum heterophyllum |
| Microcos | Microcos paniculata | |
| Sterculia | Sterculia lanceolata | |
| Firmiana | Firmiana hainanensis | |
| Fagaceae | Lithocarpus | Lithocarpus corneus |
| Castanopsis | Castanopsis formosana | |
| Meliaceae | Turraea | Turraea pubescens |
| Aglaia | Aglaia odorata var. microphyllina | |
| Toona | Toona sinensis | |
| Amoora | Amoora tsangii | |
| Dipterocarpaceae | Hopea | Hopea hainanensis |
| Vatica | Vatica mangachapoi | |
| Pandanaceae | Pandanus | Pandanus tectorius |
| Asclepiadaceae | Hoya | Hoya carnosa |
| Verbenaceae | Vitex | Vitex quinata |
| Sphenodesme | Sphenodesme pentandra | |
| Callicarpa | Callicarpa longissima | |
| Loganiaceae | Strychnos | Strychnos cathayensis |
| Strychnos angustiflora | ||
| Strychnos umbellata | ||
| Magnoliaceae | Paramichelia | Paramichelia baillonii |
| Oleaceae | Fraxinus | Fraxinus griffithii |
| Osmanthus | Osmanthus matsumuranus | |
| Jasminum | Jasminum grandiflorum | |
| Jasminum nervosum var. elegans | ||
| Connaraceae | Ellipanthus | Ellipanthus glabrifolius |
| Rourea | Rourea Microphylia | |
| Pandaceae | Microdesmis | Microdesmis caseariifolia |
| Anacardiaceae | Spondias | Spondias pinnata |
| Spondias lakonensis | ||
| Lannea | Lannea coromandelica | |
| Toxicodendron | Toxicodendron succedaneum | |
| Lythraceae | Lagerstroemia | Lagerstroemia balansae |
| Rubiaceae | Lasianthus | Lasianthus chinensis |
| Lasianthus hirsutus | ||
| Paederia | Paederia scandens | |
| Psychotria | Psychotria straminea | |
| Psychotria rubra | ||
| Tarennoidea | Tarennoidea wallichii | |
| Ixora | Ixora hainanensis | |
| Antirhea | Antirhea chinensis | |
| Fagerlindia | Fagerlindia depauperata | |
| Aidia | Aidia oxyodonta | |
| Catunaregam | Catunaregam spinosa | |
| Wendlandia | Wendlandia uvariifolia subsp. chinensis | |
| Chasalia | Chasallia curviflora | |
| Tarenna | Tarenna mollissima | |
| Canthium | Canthium horridum | |
| Rosaceae | Photinia | Photinia benthamiana |
| Moraceae | Antiaris | Antiaris toxicaria |
| Streblus | Streblus ilicifolius | |
| Streblus taxoides | ||
| Theaceae | Eurya | Eurya nitida |
| Capparaceae | Capparis | Capparis dasyphylla |
| Capparis | Capparis zeylanica | |
| Capparis hainanensis | ||
| Sapotaceae | Chrysophyllum | Chrysophyllum roxburghii |
| Sarcosperma | Sarcosperma laurinum | |
| Combretaceae | Combretum | Combretum punctatum |
| Terminalia | Terminalia hainanensis | |
| Ebenaceae | Diospyros | Diospyros strigosa |
| Diospyros cathayensis | ||
| Rhamnaceae | Sageretia | Sageretia thea |
| Myrtaceae | Syzygium | Syzygium chunianum |
| Cleistocalyx | Cleistocalyx operculatus | |
| Clusiaceae | Garcinia | Garcinia oblongifolia |
| Samydaceae | Casearia | Casearia vililimba |
| Olacaceae | Erythropalum | Erythropalum scandens |
| Celastraceae | Euonymus | Euonymus chinensis |
| Euonymus laxiflorus | ||
| Sapindaceae | Arytera | Arytera littoralis |
| Litchi | Litchi chinensis | |
| Dimocarpus | Dimocarpus longan | |
| Sapindus | Sapindus mukurossi | |
| Dilleniaceae | Tetracera | Tetracera asiatica |
| Scrophulariaceae | Paulownia | Paulownia kawakamii |
| Convolvulaceae | Erycibe | Erycibe schmidtii |
| Argyreia | Argyreia acuta | |
| Melastomataceae | Memecylon | Memecylon scutellatum |
| Ulmaceae | Gironniera | Aphananthe cuspidata |
| Caesalpiniaceae | Sindora | Peltophorum dasyrrhachis |
| Rutaceae | Murraya | Murraya exotica |
| Glycosmis | Glycosmis pentaphylla | |
| Lauraceae | Cryptocarya | Cryptocarya metcalfiana |
| Dehaasia | Dehaasia hainanensis | |
| Litsea | Litsea baviensis | |
| Litsea variabilis | ||
| Litsea monopetala | ||
| Beilschmiedia | Beilschmiedia appendiculata | |
| Machilus | Machilus suaveolens | |
| Machilus chinensis | ||
| Cinnamomum | Cinnamomum tsoi | |
| Cinnamomum burmannii | ||
| Boraginaceae | Carmona | Carmona microphylla |
| Myrsinaceae | Maesa | Maesa japonica |
| Rapanea | Rapanea neriifolia | |
| Ardisia | Ardisia densilepidotula | |
| Ardisia crenata | ||
| Bignoniaceae | Radermachera | Radermachera hainanensis |
| Markhamia | Markhamia stipulata var. kerrii | |
| Palmae | Arenga | Arenga westerhoutii |
| Daemonorops | Daemonorops margaritae | |
| Calamus | Calamus simplicifolius | |
| Caryota | Caryota ochlandra | |
| Licuala | Licuala spinosa | |
| Licuala fordiana | ||
| 53 Family | 134 Genus | 159 Species |
Table A2.
The species list of Phalaenopsis hainanensis community.
| Family | Genus | Species |
|---|---|---|
| Aspleniaceae | Neottopteris | Neottopteris nidus |
| Liliaceae | Dracaena | Dracaena cambodiana |
| Flacourtiaceae | Scolopia | Scolopia saeva |
| Euphorbiaceae | Croton | Croton cascarilloides |
| Euphorbia | Euphorbia hainanensis | |
| Drypetes | Drypetes perreticulata | |
| Actephila | Actephila merrilliana | |
| Mallotus | Mallotus tenuifolius | |
| Mallotus yunnanensis | ||
| Annonaceae | Alphonsea | Alphonsea mollis |
| Alphonsea monogyna | ||
| Artabotrys | Artabotrys hexapetalus | |
| Balsaminaceae | Impatiens | Impatiens hainanensis |
| Davalliaceae | Davallia | Davallia mariesii |
| Elaeagnaceae | Elaeagnus | Elaeagnus gonyanthes |
| Drynariaceae | Pseudodrynaria | Pseudodrynaria coronans |
| Zingiberaceae | Pommereschea | Pommereschea lackneri |
| Hamamelidaceae | Distylium | Distylium racemosum |
| Malvaceae | Erythropsis | Erythropsis pulcherrima |
| Sterculia | Sterculia lanceolata | |
| Acanthaceae | Barleria | Barleria cristata |
| Fagaceae | Quercus | Quercus bawanglingensis |
| Gesneriaceae | Chirita | Chirita heterotricha |
| Orchidaceae | Coelogyne | Coelogyne fimbriata |
| Luisia | Luisia morsei | |
| Eria | Eria quinquelamellosa | |
| Eria gagnepainii | ||
| Dendrobium | Dendrobium aurantiacum var. denneanum | |
| Dendrobium aduncum | ||
| Pholidota | Pholidota yunnanensis | |
| Cryptochilus | Cryptochilus roseus | |
| Vanda | Vanda subconcolor | |
| Liparis | Liparis viridiflora | |
| Liparis yunnanensis | ||
| Meliaceae | Aglaia | Aglaia odorata var. microphyllina |
| Loganiaceae | Fagraea | Fagraea ceilanica |
| Magnoliaceae | Paramichelia | Paramichelia baillonii |
| Oleaceae | Fraxinus | Fraxinus griffithii |
| Osmanthus | Osmanthus matsumuranus | |
| Jasminum | Jasminum nervosum var. elegans | |
| Anacardiaceae | Pistacia | Pistacia chinensis |
| Rubiaceae | Antirhea | Antirhea chinensis |
| Begoniaceae | Begonia | Begonia peltatifolia |
| Moraceae | Streblus | Streblus ilicifolius |
| Streblus taxoides | ||
| Ficus | Ficus subpisocarpa | |
| Ficus parvifolia | ||
| Ficus tinctoria subsp. gibbosa | ||
| Sapotaceae | Planchonella | Planchonella obovata |
| Myrtaceae | Decaspermum | Decaspermum gracilentum |
| Cela | Mi | |
| Euonymus | Euonymus laxiflorus | |
| Ar | Sc | |
| Ulmaceae | Celtis | Celtis sinensis |
| Ulmus | Ulmus tonkinensis | |
| Caesalpiniaceae | Gleditsia | Gleditsia sinensise |
| Rutaceae | Clausena | Clausena excavate |
| Micromelum | Micromelum falcatum | |
| Lauraceae | Dehaasia | Dehaasia hainanensis |
| Myrsinaceae Bignoniaceae | Rapanea | Rapanea linearis |
| Radermachera | Radermachera frondosa | |
| 34 Famliy | 53 Genus | 61 Species |
Appendix B
Appendix B.1. Method for Estimating the Vertical Projected Area of Epiphytic Individuals
To standardize coverage measurements on irregular trunk surfaces, the outline of each epiphytic individual was visually projected onto an imaginary vertical plane parallel to the host trunk. The maximum height and maximum lateral width of the projected outline were measured using a ruler or calipers, and the projected area was calculated as height × width. This approach follows common practice in tropical epiphyte community surveys and allows consistent comparisons across heterogeneous substrates.
Appendix B.2. Supplementary Notes on Herb Layer Assessment
The field sites were located in steep and narrow river valleys or fragmented limestone terrain, where the ground surface was highly discontinuous and often inaccessible. These terrain conditions severely limited the establishment of herbaceous plots and hindered reliable quantitative measurement of herb-layer species. As a result, the herbaceous layer could not be consistently sampled across quadrats, and diversity metrics were therefore not calculated for this stratum.
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Figure 1.
The location of Bawangling Nature Reserve (BNR) in Hainan Island (Modified from Long et al. [20]).
Figure 1.
The location of Bawangling Nature Reserve (BNR) in Hainan Island (Modified from Long et al. [20]).
Figure 2.
The distribution of sample plots of Phalaenopsis deliciosa and Phalaenopsis hainanensis in Bawangling.
Figure 2.
The distribution of sample plots of Phalaenopsis deliciosa and Phalaenopsis hainanensis in Bawangling.
Figure 3.
Spatial three-dimensional distribution of three Phalaenopsis deliciosa populations. Note: The red ball represents the spatial position of the plant, and the green, blue and black solid dots represent the projection of the plant position on each plane, respectively.
Figure 3.
Spatial three-dimensional distribution of three Phalaenopsis deliciosa populations. Note: The red ball represents the spatial position of the plant, and the green, blue and black solid dots represent the projection of the plant position on each plane, respectively.
Figure 4.
Spatial distribution pattern of three Phalaenopsis deliciosa populations. Note: (A) observed O(r)-statistic estimates for univariate analysis. The black solid circle represents the O(r) value at different distance r. Envelopes defined by the 5% highest and lowest values generated from 999 Monte Carlo simulations under the null hypothesis of complete spatial randomness (CSR) are indicated by gray lines. The thin solid line indicates the first-order intensity (λ) of the point pattern within populations. bLO(r) represents the slope of the linear regression of the O-ring statistic, O(r) against log spatial distance, ln(r). * p < 0.05, ** p < 0.01. (B) Vertical distribution pattern.
Figure 4.
Spatial distribution pattern of three Phalaenopsis deliciosa populations. Note: (A) observed O(r)-statistic estimates for univariate analysis. The black solid circle represents the O(r) value at different distance r. Envelopes defined by the 5% highest and lowest values generated from 999 Monte Carlo simulations under the null hypothesis of complete spatial randomness (CSR) are indicated by gray lines. The thin solid line indicates the first-order intensity (λ) of the point pattern within populations. bLO(r) represents the slope of the linear regression of the O-ring statistic, O(r) against log spatial distance, ln(r). * p < 0.05, ** p < 0.01. (B) Vertical distribution pattern.
Figure 5.
The number of individuals (A) and the average distribution frequency in vertical spatial distributions (B) the three Phalaenopsis deliciosa populations. Note: The same letter along columns are not significantly different.
Figure 5.
The number of individuals (A) and the average distribution frequency in vertical spatial distributions (B) the three Phalaenopsis deliciosa populations. Note: The same letter along columns are not significantly different.
Figure 6.
Spatial three-dimensional distribution of nine Phalaenopsis hainanensis sample plots. Note: Sample plots P1 to P6 are located in EXL population and P7 to P9 are located in YZC population. The red ball represents the spatial position of the plant, and the green, blue and black solid dots represent the projection of the plant position on each plane, respectively.
Figure 6.
Spatial three-dimensional distribution of nine Phalaenopsis hainanensis sample plots. Note: Sample plots P1 to P6 are located in EXL population and P7 to P9 are located in YZC population. The red ball represents the spatial position of the plant, and the green, blue and black solid dots represent the projection of the plant position on each plane, respectively.
Figure 7.
Spatial distribution pattern of four Phalaenopsis hainanensis sample plots. Note: Observed O(r)-statistic estimates for univariate analysis. The black solid circle represents the O(r) value at different distance r. Envelopes defined by the 5% highest and lowest values generated from 999 Monte Carlo simulations under the null hypothesis of complete spatial randomness (CSR) are indicated by gray lines. The thin solid line indicates the first-order intensity (λ) of the point pattern within populations. bLO(r) represents the slope of the linear regression of the O-ring statistic, O(r) against ln(r). * p < 0.05, ** p < 0.01, *** p < 0.001.
Figure 7.
Spatial distribution pattern of four Phalaenopsis hainanensis sample plots. Note: Observed O(r)-statistic estimates for univariate analysis. The black solid circle represents the O(r) value at different distance r. Envelopes defined by the 5% highest and lowest values generated from 999 Monte Carlo simulations under the null hypothesis of complete spatial randomness (CSR) are indicated by gray lines. The thin solid line indicates the first-order intensity (λ) of the point pattern within populations. bLO(r) represents the slope of the linear regression of the O-ring statistic, O(r) against ln(r). * p < 0.05, ** p < 0.01, *** p < 0.001.
Table 1.
Geographic information of Phalaenopsis deliciosa and Phalaenopsis hainanensis.
| Population | Longitude | Latitude | Altitude | Sample Area | No. of Quadrats |
|---|---|---|---|---|---|
| Phalaenopsisdeliciosa | |||||
| Third stage power station (SD) | E: 109° 6′3.77″ | N: 19° 6′39.97″ | 230 m | 5 m × 100 m | 1 |
| Second stage power station (ED) | E: 109° 6′56.33″ | N: 19° 5′59.18″ | 284 m | 5 m × 70 m | 1 |
| Yajia Power Station (YJ) | E: 109° 7′46.34″ | N: 19° 5′8.74″ | 476 m | 10 m × 70 m | 1 |
| Phalaenopsishainanensis | |||||
| Erxian Ridge (EXL) | E: 109° 6′34.26″ | N: 19° 0′50.89″ | 1 050 m | 10 m × 10 m | 6 |
| Coconut Village (YZC) | E: 109° 7′59.55″ | N: 19° 1′5.07″ | 600 m | 10 m × 10 m | 3 |
Table 2.
The species’ importance value in tree layer of Phalaenopsis deliciosa community.
| Population | Host Species | Relative Abundance | Relative Frequency | Relative Coverage | Importance Value |
|---|---|---|---|---|---|
| YJ | Streblus taxoides | 19.13 | 8.72 | 9.28 | 12.37 |
| Erismanthus sinensis | 7.54 | 5.96 | 11.99 | 8.50 | |
| Streblus ilicifolius | 8.70 | 5.50 | 7.56 | 7.25 | |
| Hydnocarpus hainanensis | 7.25 | 7.80 | 5.38 | 6.81 | |
| ED | Mallotus peltatus | 14.29 | 8.41 | 10.15 | 10.95 |
| Erismanthus sinensis | 5.44 | 4.67 | 7.85 | 5.99 | |
| SD | Streblus ilicifolius | 35.62 | 13.71 | 21.11 | 23.48 |
| Streblus taxoides | 24.12 | 12.57 | 11.06 | 15.92 | |
| Terminalia hainanensis | 3.98 | 6.86 | 30.56 | 13.80 | |
| Dasymaschalon trichophorum | 6.86 | 9.14 | 4.49 | 6.83 | |
| Cleistanthus concinnus | 4.65 | 6.86 | 4.30 | 5.27 | |
| Total | Streblus ilicifolius | 20.13 | 7.20 | 10.80 | 12.71 |
| Streblus taxoides | 18.44 | 8.20 | 8.23 | 11.62 | |
| Terminalia hainanensis | 2.00 | 2.60 | 10.90 | 5.17 |
Note: Only species with an important value greater than 5% are listed.
Table 3.
The species’ importance value in shrub layer of Phalaenopsis deliciosa community.
| Population | Host Species | Relative Abundance | Relative Frequency | Relative Coverage | Importance Value |
|---|---|---|---|---|---|
| YJ | Schizostachyum pseudolima | 30.28 | 13.51 | 58.64 | 34.14 |
| Streblus ilicifolius | 11.31 | 6.76 | 10.26 | 9.44 | |
| Streblus taxoides | 8.56 | 6.08 | 11.62 | 8.75 | |
| Dasymaschalon trichophorum | 7.95 | 9.46 | 4.20 | 7.20 | |
| ED | Schizostachyum pseudolima | 50.78 | 20.00 | 75.26 | 48.68 |
| Licuala fordiana | 8.59 | 7.27 | 11.68 | 9.18 | |
| SD | Schizostachyum pseudolima | 20.42 | 17.98 | 57.08 | 31.83 |
| Streblus ilicifolius | 25.46 | 23.60 | 13.43 | 20.83 | |
| Dasymaschalon trichophorum | 15.38 | 15.73 | 15.19 | 15.44 | |
| Streblus taxoides | 16.45 | 14.61 | 6.96 | 12.67 | |
| Actephila merrilliana | 16.98 | 14.61 | 4.48 | 12.02 | |
| Total | Schizostachyum pseudolima | 28.93 | 16.04 | 63.67 | 36.21 |
| Dasymaschalon trichophorum | 10.32 | 10.24 | 7.05 | 9.20 | |
| Streblus taxoides | 10.80 | 7.51 | 5.92 | 8.08 | |
| Streblus ilicifolius | 11.52 | 7.17 | 5.10 | 7.93 | |
| Actephila merrilliana | 8.76 | 6.14 | 2.07 | 5.66 |
Note: Only species with an important value greater than 5% are listed.
Table 4.
The species’ importance value in tree layer of Phalaenopsis hainanensis community.
| Population | Host Species | Relative Abundance | Relative Frequency | Relative Coverage | Importance Value |
|---|---|---|---|---|---|
| EXL | Quercus bawanglingensis | 15.84 | 5.41 | 19.37 | 13.54 |
| Streblus ilicifolius | 14.85 | 8.11 | 17.21 | 13.39 | |
| Mallotus yunnanensis | 19.80 | 5.41 | 11.28 | 12.16 | |
| Sterculia lanceolata | 8.91 | 8.11 | 6.48 | 7.83 | |
| Aglaia odorata var. microphyllina | 5.94 | 5.41 | 4.49 | 5.28 | |
| Osmanthus matsumuranus | 1.98 | 5.41 | 8.29 | 5.22 | |
| YZC | Streblus ilicifolius | 14.74 | 4.65 | 13.21 | 10.86 |
| Clausena excavata | 16.84 | 6.98 | 7.52 | 10.45 | |
| Dehaasia hainanensis | 7.37 | 9.30 | 12.13 | 9.60 | |
| Mallotus yunnanensis | 7.37 | 2.33 | 14.24 | 7.98 | |
| Total | Streblus ilicifolius | 14.87 | 6.33 | 14.43 | 11.88 |
| Mallotus yunnanensis | 13.85 | 3.80 | 13.46 | 10.37 | |
| Dehaasia hainanensis | 4.62 | 6.33 | 9.56 | 6.83 | |
| Clausena excavata | 8.72 | 5.06 | 6.31 | 6.70 | |
| Quercus bawanglingensis | 9.23 | 3.80 | 5.90 | 6.31 | |
| Sterculia lanceolata | 6.67 | 6.33 | 3.26 | 5.42 |
Note: Only species with an important value greater than 5% are listed.
Table 5.
The species’ importance value in shrub layer of Phalaenopsis hainanensis community.
| Population | Host Species | Relative Abundance | Relative Frequency | Relative Coverage | Importance Value |
|---|---|---|---|---|---|
| EXL | Mallotus yunnanensis | 38.46 | 12.50 | 46.88 | 32.61 |
| Croton cascarilloides | 19.23 | 12.50 | 23.44 | 18.39 | |
| YZC | Schefflera arboricola | 16.67 | 50.00 | 67.57 | 44.74 |
| Paramichelia baillonii | 83.33 | 50.00 | 32.43 | 55.26 | |
| Total | Mallotus yunnanensis | 31.25 | 11.11 | 36.36 | 26.24 |
| Schefflera arboricola | 12.50 | 22.22 | 24.24 | 19.65 | |
| Croton cascarilloides | 15.63 | 11.11 | 18.18 | 14.97 | |
| Paramichelia baillonii | 15.63 | 11.11 | 7.27 | 11.34 |
Note: Only species with an important value greater than 5% are listed.
Table 6.
The flora distribution of vascular plants of Phalaenopsis deliciosa and Phalaenopsis hainanensis community.
Table 6.
The flora distribution of vascular plants of Phalaenopsis deliciosa and Phalaenopsis hainanensis community.
| Geographical Areal-Types | Phalaenopsis deliciosa | Phalaenopsis hainanensis | ||
|---|---|---|---|---|
| No. of Genus | Proportion | No. of Genus | Proportion | |
| 1 Cosmopolitan | 1 | 0.75 | 3 | 5.66 |
| 2 Pantropic | 29 | 21.64 | 14 | 26.42 |
| 3 Trop. Asia & Trop. Amer. disjuncted | 6 | 4.48 | 1 | 1.89 |
| 4 Old World Tropics | 18 | 13.43 | 4 | 7.55 |
| 5 Trop. Asia toTrop. Australasia | 21 | 15.67 | 8 | 15.09 |
| 6 Trop. Asia to Trop. Africa | 13 | 9.7 | 1 | 1.89 |
| 7 Trop. Asia: India-Malasia | 41 | 30.6 | 13 | 24.53 |
| 8 North Temperate | 1 | 0.75 | 5 | 9.43 |
| 9 E. Asia & N. Amer. disjuncted | 2 | 1.49 | 1 | 1.89 |
| 12 Central Asia, West Asia to the Mediterranean | / | / | 1 | 1.89 |
| 14 E. Asia | 2 | 1.49 | 2 | 3.77 |
| Total | 134 | 100 | 53 | 100 |
| Shannon—Wiener Index | H′ = 1.818 | H′ = 1.985 | ||
Table 7.
Epiphytic selective index of Phalaenopsis deliciosa.
| Species | Abundance | Frequence | Total Plants | Relative Abundance | Relative Frequency | Relative Dominance | Epiphytic Index |
|---|---|---|---|---|---|---|---|
| Streblus ilicifolius | 40 | 36 | 82 | 23.39 | 12.12 | 30.15 | 21.89 |
| Streblus taxoides | 34 | 41 | 55 | 19.88 | 13.80 | 20.22 | 17.97 |
| Mallotus peltatus | 11 | 15 | 17 | 6.43 | 5.05 | 6.25 | 5.91 |
| Erismanthus sinensis | 9 | 18 | 15 | 5.26 | 6.06 | 5.51 | 5.61 |
| Sphenodesme pentandra | 9 | 13 | 12 | 5.26 | 4.38 | 4.41 | 4.68 |
| Hydnocarpus hainanensis | 4 | 19 | 7 | 2.34 | 6.40 | 2.57 | 3.77 |
| Artabotrys hainanensis | 7 | 7 | 10 | 4.09 | 2.36 | 3.68 | 3.38 |
| Dasymaschalon trichophorum | 3 | 18 | 5 | 1.75 | 6.06 | 1.84 | 3.22 |
| Acacia pennata | 6 | 5 | 6 | 3.51 | 1.68 | 2.21 | 2.47 |
| Koilodepas hainanense | 4 | 8 | 6 | 2.34 | 2.69 | 2.21 | 2.41 |
| Antirhea chinensis | 3 | 6 | 7 | 1.75 | 2.02 | 2.57 | 2.12 |
| Euonymus laxiflorus | 3 | 9 | 3 | 1.75 | 3.03 | 1.10 | 1.96 |
| Aporusa dioica | 1 | 12 | 1 | 0.58 | 4.04 | 0.37 | 1.66 |
| Millettia tsui | 4 | 3 | 4 | 2.34 | 1.01 | 1.47 | 1.61 |
| Tetracera asiatica | 3 | 5 | 3 | 1.75 | 1.68 | 1.10 | 1.51 |
| Ellipanthus glabrifolius | 1 | 10 | 1 | 0.58 | 3.37 | 0.37 | 1.44 |
| Diospyros cathayensis | 1 | 8 | 2 | 0.58 | 2.69 | 0.74 | 1.34 |
| Tarenna mollissima | 1 | 8 | 1 | 0.58 | 2.69 | 0.37 | 1.22 |
| Pterospermum heterophyllum | 2 | 4 | 3 | 1.17 | 1.35 | 1.10 | 1.21 |
| Strychnos angustiflora | 1 | 5 | 3 | 0.58 | 1.68 | 1.10 | 1.12 |
| Derris trifoliata | 2 | 4 | 2 | 1.17 | 1.35 | 0.74 | 1.08 |
| Vitex quinata | 1 | 5 | 2 | 0.58 | 1.68 | 0.74 | 1.00 |
| Amoora tsangii | 1 | 6 | 1 | 0.58 | 2.02 | 0.37 | 0.99 |
| Aphananthe cuspidata | 1 | 4 | 2 | 0.58 | 1.35 | 0.74 | 0.89 |
| Diploclisia glaucescens | 2 | 2 | 2 | 1.17 | 0.67 | 0.74 | 0.86 |
| Alphonsea mollis | 1 | 3 | 2 | 0.58 | 1.01 | 0.74 | 0.78 |
| Dalbergia peishaensis | 2 | 1 | 2 | 1.17 | 0.34 | 0.74 | 0.75 |
| Litchi chinensis | 1 | 3 | 1 | 0.58 | 1.01 | 0.37 | 0.65 |
| Rourea Microphylia | 1 | 2 | 1 | 0.58 | 0.67 | 0.37 | 0.54 |
| Sterculia lanceolata | 1 | 2 | 1 | 0.58 | 0.67 | 0.37 | 0.54 |
| Alyxia sinensis | 1 | 2 | 1 | 0.58 | 0.67 | 0.37 | 0.54 |
| Garcinia oblongifolia | 1 | 2 | 1 | 0.58 | 0.67 | 0.37 | 0.54 |
| Sarcosperma laurinum | 1 | 2 | 1 | 0.58 | 0.67 | 0.37 | 0.54 |
| Hunteria zeylanica | 1 | 2 | 1 | 0.58 | 0.67 | 0.37 | 0.54 |
| Argyreia acuta | 1 | 1 | 1 | 0.58 | 0.34 | 0.37 | 0.43 |
| Fissistigma oldhamii | 1 | 1 | 1 | 0.58 | 0.34 | 0.37 | 0.43 |
| Fraxinus griffithii | 1 | 1 | 1 | 0.58 | 0.34 | 0.37 | 0.43 |
| Murraya exotica | 1 | 1 | 1 | 0.58 | 0.34 | 0.37 | 0.43 |
| Ormosia semicastrata f. litchiifolia | 1 | 1 | 1 | 0.58 | 0.34 | 0.37 | 0.43 |
| Jasminum nervosum var. elegans | 1 | 1 | 1 | 0.58 | 0.34 | 0.37 | 0.43 |
Table 8.
Epiphytic selective index of Phalaenopsis hainanensis.
| Species | Abundance | Frequence | Total Plants | Relative Abundance | Relative Frequency | Relative Dominance | Epiphytic Index |
|---|---|---|---|---|---|---|---|
| Streblus ilicifolius | 8 | 5 | 19 | 23.53 | 13.16 | 41.30 | 26.00 |
| Mallotus yunnanensis | 9 | 3 | 9 | 26.47 | 7.89 | 19.57 | 17.98 |
| Sterculia lanceolata | 2 | 5 | 2 | 5.88 | 13.16 | 4.35 | 7.80 |
| Ulmus tonkinensis | 1 | 5 | 1 | 2.94 | 13.16 | 2.17 | 6.09 |
| Clausena excavata | 1 | 4 | 1 | 2.94 | 10.53 | 2.17 | 5.21 |
| Osmanthus matsumuranus | 1 | 3 | 1 | 2.94 | 7.89 | 2.17 | 4.34 |
| Schefflera arboricola | 2 | 1 | 2 | 5.88 | 2.63 | 4.35 | 4.29 |
| Fraxinus griffithii | 1 | 2 | 1 | 2.94 | 5.26 | 2.17 | 3.46 |
| Antirhea chinensis | 1 | 2 | 1 | 2.94 | 5.26 | 2.17 | 3.46 |
| Erythropsis pulcherrima | 1 | 1 | 2 | 2.94 | 2.63 | 4.35 | 3.31 |
| Ficus subpisocarpa | 1 | 1 | 1 | 2.94 | 2.63 | 2.17 | 2.58 |
| Microtropis submembranacea | 1 | 1 | 1 | 2.94 | 2.63 | 2.17 | 2.58 |
| Radermachera frondosa | 1 | 1 | 1 | 2.94 | 2.63 | 2.17 | 2.58 |
| Jasminum nervosum var. elegans | 1 | 1 | 1 | 2.94 | 2.63 | 2.17 | 2.58 |
| Ficus parvifolia | 1 | 1 | 1 | 2.94 | 2.63 | 2.17 | 2.58 |
| Streblus taxoides | 1 | 1 | 1 | 2.94 | 2.63 | 2.17 | 2.58 |
| Artabotrys hexapetalus | 1 | 1 | 1 | 2.94 | 2.63 | 2.17 | 2.58 |
Table 9.
The individual number of vertical distributions in nine sample plots.
| Population | Sample Plot Number | Epiphytic Height (m) | Total | |||
|---|---|---|---|---|---|---|
| 0–0.9 | 1–1.9 | 2–2.9 | 3–4 | |||
| EXL | P1 | 5 | 7 | 8 | 1 | 21 |
| P2 | 5 | 1 | 0 | 0 | 6 | |
| P3 | 0 | 5 | 4 | 0 | 9 | |
| P4 | 0 | 0 | 1 | 9 | 10 | |
| P5 | 10 | 0 | 0 | 0 | 10 | |
| P6 | 0 | 0 | 10 | 0 | 10 | |
| YZC | P7 | 2 | 0 | 0 | 0 | 4 |
| P8 | 0 | 4 | 1 | 0 | 5 | |
| P9 | 3 | 0 | 1 | 0 | 4 | |
| Total | 25 | 17 | 25 | 10 | 77 | |
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MDPI and ACS Style
Zhong, H.; Li, W.; Chen, Z.; Zhang, Z. Epiphytic Habit and Spatial Distribution Patterns of Phalaenopsis deliciosa and Phalaenopsis hainanensis. Diversity 2025, 17, 818. https://doi.org/10.3390/d17120818
AMA Style
Zhong H, Li W, Chen Z, Zhang Z. Epiphytic Habit and Spatial Distribution Patterns of Phalaenopsis deliciosa and Phalaenopsis hainanensis. Diversity. 2025; 17(12):818. https://doi.org/10.3390/d17120818
Chicago/Turabian StyleZhong, Haotian, Wenchang Li, Zhiheng Chen, and Zhe Zhang. 2025. "Epiphytic Habit and Spatial Distribution Patterns of Phalaenopsis deliciosa and Phalaenopsis hainanensis" Diversity 17, no. 12: 818. https://doi.org/10.3390/d17120818
APA StyleZhong, H., Li, W., Chen, Z., & Zhang, Z. (2025). Epiphytic Habit and Spatial Distribution Patterns of Phalaenopsis deliciosa and Phalaenopsis hainanensis. Diversity, 17(12), 818. https://doi.org/10.3390/d17120818
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