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Hainan Island has the most extensive and well‐preserved tropical forests in China. With rapid economic development of Hainan, biodiversity is increasingly at risk. Determining the spatial patterns of plant diversity in Hainan and explaining the drivers behind plant diversity are important considerations in assessing and maximizing the effectiveness of national parks, such as the newly designated Hainan Rainforest National Park. We assessed phylogenetic diversity patterns, and species richness using 106,252 georeferenced specimen records and a molecular phylogeny of 3,792 native plant species. Based on phylogenetic range‐weighted turnover metrics, we divided Hainan flora into four major floristic units. The Grade of Membership model was used to further verify the four units, and to understand their boundaries and the internal structure of each floristic unit. Finally, the best combination model was used to explore the driving mechanisms underlying the division. Our results reveal that central Hainan is the most important hotspot for plant endemism and diversity, followed by the southern area. Environmental energy is the main factor determining the spatial patterns of native plant diversity on the island, and accessibility has the greatest impact on native plant diversity among social factors. We explore patterns of spatial phylogenetics and biogeography to identify potential priorities for management and conservation drivers of plant diversity patterns across Hainan, to provide the basis for the effective protection of native plant diversity and the improvement of national parks of Hainan Island. [ABSTRACT FROM AUTHOR]

Urban environments are dynamic landscapes shaped by a multitude of factors, including environmental conditions and socio-economic influences. This study systematically investigates how various factors shape urban plant diversity in Haikou City, Hainan Province, China, focusing on 30 key drivers including socioeconomic aspects, biophysical conditions, landscape elements, and management practices. Our research methodology involved a comprehensive analysis of these factors' impact on six types of urban plant species: spontaneous, native spontaneous, exotic spontaneous, cultivated, native cultivated, and exotic cultivated. Conducted in urban areas with varying population densities and landscape features, our sampling approach aimed to understand the species' distribution patterns. We discovered significant correlations between plant species diversity and specific environmental and socio-economic variables. Our results indicate that spontaneous species are prevalent in densely populated areas with strong social ties, whereas areas rich in tree and shrub cover see fewer such species. Native cultivated species favor more serene, less urbanized landscapes, while exotic cultivated species are predominantly found in economically affluent areas with diverse vegetation. These findings offer valuable insights for urban planning and biodiversity conservation, emphasizing the need for customized greening strategies that align with local environmental and social contexts. By adopting such tailored approaches, urban planners can more effectively manage landscapes, enrich green spaces, and foster biodiverse, sustainable ecosystems. This research not only enhances our understanding of urban plant biodiversity but also lays the groundwork for future studies and policy-making, promoting harmonious integration of diverse plant life within urban settings. [ABSTRACT FROM AUTHOR]

In this study, we investigated the relationships among species composition, diversity, distribution, growth status, and habitats of venerable trees (VTs) in Wuzhishan City, Hainan, China. VT are defined as venerable tree. VTs bear witness to changes in human society and culture; VTs that once occurred in open or forested areas are now often surrounded by or adjacent to new infrastructure and urban development. In spite of urban development, protecting VTs is important for preserving the history they contain as a part of their carbon sequestration, maintaining their unique ecological services, and continuing to appreciate and advance their cultural symbolism and meaning. We studied VTs and their habitats based on literature reviews, field surveys, interviewing local people, and tree-age determination in the laboratory. Our results revealed 216 VTs in Wuzhishan City of 100 or more years old, belonging to nine families, 13 genera and 21 species. Among families, Sapindaceae comprised the largest number of VTs with 79 species and was especially represented by the fruit tree, Litchi chinensis Sonn (Lychee). Perhaps unsurprisingly, we also found that older VTs were rarer than younger ones with the age structure being 192 VTs 100–299 years old, 21 trees 300–499 years old, and only three trees 500 years old or older. The average age was 163 years. Tree height, trunk girth, and crown width had normal distributions, with means of mean 32.1 m, 423 cm, 17 m, respectively. Overall, VTs were more-or-less evenly distributed across the study area, though there were biases in location when age was taken into account with older trees tending to occur at mid-elevations within the study area, but at higher elevations than other VTs. We applied a general linear model (GLM) to analyze the association between attributes of VTs and environmental data. The models revealed significant correlations between tree height and precipitation of the wettest month (p = 8.69 × 10–4), trunk girth and mean annual temperature (p = 9.30 × 10–4) and precipitation of the coldest quarter (p = 3.06 × 10–4), and crown width and mean temperature of the warmest quarter (p = 8.28 × 10–3). In conclusion, Wuzhishan City is home to diverse VTs with distributions driven at least in part by environmental factors (e.g.,temperature, precipitation, elevation, etc.). VTs can be maintained through enhanced conservation measures that acknowledge their cultural, ecological, and historical value. [ABSTRACT FROM AUTHOR]

Understanding large-scale patterns of biodiversity and their drivers remains central in ecology. Many hypotheses have been proposed, including hydrothermal dynamic hypothesis, tropical niche conservatism hypothesis, Janzen's hypothesis and a combination model containing energy, water, seasonality and habitat heterogeneity. Yet, their relative contributions to groups with different lifeforms and range sizes remain controversial, which have limited our ability to understand the general mechanisms underlying species richness patterns. Here we evaluated how lifeforms and species range sizes influenced the relative contributions of these three hypotheses to species richness patterns of a tropical family Moraceae. The distribution data of Moraceae species at a spatial resolution of 50 km × 50 km and their lifeforms (i.e. shrubs, small trees and large trees) were compiled. The species richness patterns were estimated for the entire family, different life forms and species with different range sizes separately. The effects of environmental variables on species richness were analyzed, and relative contributions of different hypotheses were evaluated across life forms and species range size groups. The species richness patterns were consistent across different species groups and the species richness was the highest in Sichuan, Guangzhou and Hainan provinces, making these provinces the hotspots of this family. Climate seasonality is the primary factor in determining richness variation of Moraceae. The best combination model gave the largest explanatory power for Moraceae species richness across each group of range size and life forms followed by the hydrothermal dynamic hypothesis, Janzen's hypothesis and tropical niche conservatism hypothesis. All these models has a large shared effects but a low independent effect (< 5%), except rare species. These findings suggest unique patterns and mechanisms underlying rare species richness and provide a theoretical basis for protection of the Moraceae species in China. [ABSTRACT FROM AUTHOR]

Simple Summary: The relationship between urban plant diversity (UPD) and above ground biomass (AGB) were assessed across 190 urban functional units in Haikou's tropical urban ecosystems. UPD and AGB showed time-lag effects to human activities and socioeconomics. Understanding the drivers of urban plant diversity (UPD) and above ground biomass (AGB) in urbanized areas is critical for urban ecosystem services and biodiversity protection. The relationships between UPD and AGB have been investigated simultaneously. However, the drivers of UPD and AGB have been explored independently in tropical coastal areas at different time points. To fill this gap, we conducted a remote sensing interpretation, field plant plot surveys, and compiled socioeconomic and urban greening management survey data. We conducted spatial analyses to investigate the relationships among UPD and socioeconomic variables across different primary and secondary urban functional units (UFUs) in the tropical urban ecosystems of the coastal city of Haikou, China. The primary UFUs with the highest AGB were the recreation and leisure districts in 2015 and 2021. In 2015, AGB was mainly correlated with the number of herb species in undeveloped land and the districts of industry, business, recreation, and leisure. In 2021, AGB was affected primarily by the frequency of fertilizing, maintenance, and watering. Our study found that the relationship between UPD and AGB varied across time and space in Haikou. The plant diversity and AGB's response to human activities and socioeconomics appear to have a time-lag effect. These results provide new insights in understanding how management decisions affect urban vegetation and could be used to guide future urban green space planning in Haikou. [ABSTRACT FROM AUTHOR]

Artocarpus altilis (Parkinson ex F.A. Zorn) Fosberg is native to the Pacific Islands, India, and the Philippines. It is also cultivated in Taiwan and Hainan. The complete plastome of the species was assembled and annotated in this study. The circular genome was 160,184 bp in size, presenting a typical quadripartite structure including two inverted repeats (IRs) of 25,734 bp, a large single-copy (LSC) of 88,791 bp, and a small single-copy (SSC) of 19,925 bp. The genome contained 132 genes, including 87 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The total G/C content of complete plastome was 36.0%, with the corresponding values of the LSC, SSC, and IR being 33.7%, 28.8%, and 42.7%, respectively. The complete plastome sequence of A. altilis (Parkinson ex F.A. Zorn) Fosberg will make contributions to the conservation genetics of this species as well as to phylogenetic studies of Moraceae. [ABSTRACT FROM AUTHOR]

The roles of natural and anthropogenic factors in contributing to the organization of biodiversity at large and small scales have long been challenging to disentangle, and doing so has never been attempted for the island province of Hainan in China based on patterns of taxonomic and phylogenetic diversity. Therefore, in this study, we evaluated the taxonomic and phylogenetic diversity of endemic plants on the island as a function of anthropogenic and natural variables based on non-metric multi-dimensional scaling (NMDS) ordination and generated generalized linear models (GLMs). We found that the highest phylogenetic diversity (1006) and the lowest mean phylogenetic distance (515.5) was in the provincial capital, Haikou. The NMDS analyses indicated that taxonomic diversity was significantly correlated with industrial revenue (p = 0.006) and population (p = 0.004). Furthermore, most phylogenetic diversity indices were strongly correlated with population and agricultural revenue, while the sampled natural environmental variables were not significantly correlated with plant diversity indices. These findings indicate that anthropogenic factors are the main present-day driving forces of plant diversity in Hainan, though we did detect a significant latitudinal diversity gradient of richness that likely reflects the historical roles of natural environmental factors in the organization of biodiversity on the island. Overall, our results are alarming for biodiversity of the island and indicate that conservation and sustainable use of endemic plant species must be made a critical priority. [ABSTRACT FROM AUTHOR]

To better identify biodiversity hotspots for conservation on Hainan Island, a tropical island in southern China, we assessed spatial variation in phylogenetic diversity and species richness using 18,976 georeferenced specimen records and a newly reconstructed molecular phylogeny of 957 native woody plants. Within this framework, we delineated bioregions based on vegetation composition and mapped areas of neoendemism and paleoendemism to identify areas of priority for conservation. Our results reveal that the southwest of Hainan is the most important hot spot for endemism and plant diversity followed by the southeast area. The distribution of endemic species showed a scattered, rather than clustered, pattern on the island. Based on phylogenetic range‐weighted turnover metrics, we delineated three major vegetational zones in Hainan. These largely correspond to natural secondary growth and managed forests (e.g., rubber and timber forests) in central Hainan, old‐growth forests and natural secondary growth forest at the margins of Hainan, and nature reserves on the island (e.g., Jianfeng and Diaoluo National Nature Reserves). Our study helps to elucidate potential botanical conservation priorities for Hainan within an evolutionary, phylogenetic framework. [ABSTRACT FROM AUTHOR]

Spondias dulcis is a deciduous tree in the family Anacardiaceae. The species originates in South America and now is widely cultivated in tropical areas due to its edible fruits. In this study, we find that the length of the complete plastome of S. dulcis is 162,256 bp. It includes 35 tRNA genes and eight rRNA genes, 86 protein-coding genes and totally 130 genes. The complete plastome of S. dulcis includes a small single-copy (SSC) region of 18,459 bp, a large single-copy (LSC) region of 89,353 bp, and two inverted repeats (IRs) regions of 27,222 bp. The total G/C content of S. dulcis is 37.7%. It shows that S. dulcis is closely related to S. mombin within Anacardiaceae. It will contribute to the conservation genetics of S. dulcis and the phylogenetic studies in Anacardiaceae. [ABSTRACT FROM AUTHOR]

Syzygium odoratum (Lour.) DC. 1828 is a deciduous shrub in the family Myrtaceae. This species grows in sparse forests, especially in mountains, valleys, and broad-leaved evergreen forests along streams from 100 to 400 m above sea level. The primary distribution is in southern China (e.g. Guangdong, Guangxi, Hainan, etc.) and other south Asian countries (e.g. Vietnam). Here, we report and characterize the complete plastome from a cultivar of S. odoratum (Lour.) DC. 1828. The complete plastome is 159,352 bp in length with a typical structure and gene content found in angiosperms, including two inverted repeat regions (IRs) of 26,472 bp, a large single-copy (LSC) region of 87,993 bp, and a small single-copy (SSC) region of 18,415 bp. The plastome contains 132 genes, consisting of 84 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The overall G/C content in the plastome of S. odoratum is 36.9%. By inferring phylogenetic relationships based on the existing data of related taxa, we find that S. odoratum is most closely related to Syzygium acuminatissimum, (Blume) DC. 1828 given the current sampling. The complete plastome sequence of S. odoratum will provide a useful resource for conservation genetics of this species, as well as for phylogenetic studies involving Myrtaceae. [ABSTRACT FROM AUTHOR]

Drivers of patterns in plant diversity remain poorly understood in tropical cities. Therefore, we investigated diversity within the tropical city of Sanya in Hainan Province of southern China by sampling one to three plots within 154 urban functional units (UFUs) based on six primary and 18 secondary UFUs. To measure diversity, we determined the number of vascular plants (species richness; SR) within each functional unit based on vegetation plots. We computed Faith's phylogenetic diversity (PD Faith) using a large megatree of plant life. To assess the potential drivers of SR and PD Faith, we performed multiple regressions using socioeconomic, biophysical, and vegetation management variables. The results showed significant differences in SR and PD Faith among the six primary UFUs. PD Faith of cultivated species was significantly higher than PD Faith of spontaneous species in all UFUs except in the wasteland area. Management measures were better predictors of SR and PD Faith than socioeconomic variables. The best predictor of SR and PD Faith of spontaneous species was the management of the urban green space. Our results provide clear guidelines for improved management strategies in Sanya, especially by showing how spontaneous and/or cultivated plant diversity can be encouraged depending on environmental, ecological, and cultural needs. Our work also adds to the presently scarce literature on drivers of urban plant diversity in tropical cities worldwide. [ABSTRACT FROM AUTHOR]

Mallotus peltatus is a tropical plant of the Euphorbiaceae family, which could be used as a beverage and medicine in Hainan, China. Here, we report and characterize the complete plastome of M. peltatus. The complete plastome is 163,304 bp in length and contains a typical structure and gene content of angiosperm plastome, including two inverted repeat (IR) regions of 27,112 bp, a large single-copy (LSC) region of 89,886 bp and a small single-copy (SSC) region of 18,840 bp. The plastome contains 131 genes, consisting of 78 unique protein-coding genes, 30 unique tRNA gene, four unique rRNA genes (5S rRNA, 4.5S rRNA, 23S rRNA and 16S rRNA), and eight pseudogenes. The overall A/T content in the plastome of M. peltatus is 64.02%. The complete plastome sequence of M. peltatus will provide a useful resource for the conservation genetics of this species as well as for phylogenetic studies in Euphorbiaceae. [ABSTRACT FROM AUTHOR]

Croton laevigatus grows as an evergreen tree or shrub with 15 meters height. It is distributed in the dense or open forests of Hainan province, China. Here, we report and characterize the complete plastome of C. laevigatus in an effort to provide genomic resources useful for promoting its systematics research. The plastome of C. laevigatus is found to possess a total length 162,515 bp with the typical quadripartite structure of angiosperms, contains two Inverted Repeats (IRs) of 26,866 bp, a Large Single-Copy (LSC) region of 90,234 bp and a Small Single-Copy (SSC) region of 18,549 bp. The plastome contains 113 genes, consisting of 79 unique protein-coding genes, 30 unique tRNA genes and four unique rRNA genes. The overall A/T content in the plastome of C. laevigatus is 64.10%. The phylogenetic analysis indicated that C. laevigatus is close to C. tiglium within Euphorbiaceae in this study. The complete plastome sequence of C. laevigatus will provide a useful resource for the conservation genetics of this species as well as for the phylogenetic studies of Euphorbiaceae. [ABSTRACT FROM AUTHOR]

Magnolia fordiana var. hainanensis (Dandy) Noot. (Magnoliaceae) is an endemic and ornamental tree distributed in Hainan, China. In this study, we report and characterize the complete plastid genome sequence of M. fordiana var. hainanensis in order to provide genomic resources helpful for promoting its conservation and garden utilization. The complete plastome is 160,157 bp in length and contains the typical quadripartite structure of angiosperm, including two Inverted Repeat (IRs) regions of 26,573 bp, a Large Single-Copy (LSC) region of 88,255 bp and a Small Single-Copy (SSC) region of 18,756 bp. The plastome contains 114 genes, consisting of 80 unique protein-coding genes, 30 unique tRNA gene and 4 unique rRNA genes. The overall A/T content in the plastome of M. fordiana var. hainanensis is 60.70%. The complete plastome sequence of M. fordiana var. hainanensis will provide a useful resource for the conservation and garden utilization of this species as well as for the phylogenetic studies of Magnoliaceae. [ABSTRACT FROM AUTHOR]

Salacia amplifolia belongs to Celastraceae. The complete plastome of S.amplifolia is 163,255 bp in length, including two inverted repeat (IR) regions of 28,932 bp, a large single-copy (LSC) region of 86,856 bp, and a small single-copy (SSC) region of 18,535 bp. The plastome contains 113 genes, consisting of 79 unique protein-coding genes, 30 unique tRNA genes, and 4 unique rRNA genes. The overall A/T content in the plastome of S. amplifolia is 62.50%. The complete plastome sequence of S. amplifolia will provide a useful resource for the conservation genetics of this specie as well as for the phylogenetic studies of Salacia. [ABSTRACT FROM AUTHOR]

Hedyotis ovata is a plant of the family Rubiaceae. So far, there is no study on the genome of H. ovata. Here, we report and characterize the complete plastid genome sequence of H. ovata in an effort to provide genomic resources useful for promoting its conservation. The complete plastome is 154,560 bp in length and contains the typical structure and gene content of angiosperm plastome, including two inverted repeat (IR) regions of 26,058 bp, a large single-copy (LSC) region of 84,579 bp and a small single-copy (SSC) region of 17,865 bp. The plastome contains 114 genes, consisting of 80 unique protein-coding genes, 30 unique tRNA genes, and 4 unique rRNA genes. The overall A/T content in the plastome of H. ovata is 61.90%. The complete plastome sequence of H. ovata will provide a useful resource for the conservation genetics of this species as well as for the phylogenetic studies for Rubiaceae. [ABSTRACT FROM AUTHOR]

Saprosma merrillii is a plant of the family Rubiaceae. So far, there is no study on the genome of S. merrillii. Here, we report and characterize the complete plastid genome sequence of S. merrillii in an effort to provide genomic resources useful for promoting its conservation. The complete plastome is 155,820 bp in length and contains the typical structure and gene content of angiosperm plastome, including two Inverted Repeat (IR) regions of 26,228 bp, a Large Single-Copy (LSC) region of 85,625 bp and a Small Single-Copy (SSC) region of 17,739 bp. The plastome contains 114 genes, consisting of 80 unique protein-coding genes, 30 unique tRNA genes, and 4 unique rRNA genes. The overall A/T content in the plastome of S. merrillii is 62.50%. The complete plastome sequence of S. merrillii will provide a useful resource for the conservation genetics of this species as well as for the phylogenetic studies for Rubiaceae. [ABSTRACT FROM AUTHOR]

Clinacanthus nutans (Burm.f.) Lindau. is a medicinal species occurring in southern Guangdong province, Guangxi province, Hainan province and Yunnan province of China, which has been widely used in the medical field. However, its complete plastome information and systematic position are still unknown. In order to enhance the development of its medicinal value, we report and characterize the complete plastid genome sequence of C. nutans in an effort to provide genomic resources useful to promoting its medicinal value and systematic research. The complete plastome is 151,669 bp in length and contains the typical structure and gene content of angiosperm plastome, including two Inverted Repeat (IR) regions of 25,366 bp, a Large Single-Copy (LSC) region of 83,502 bp and a Small Single-Copy (SSC) region of 17,435 bp. The plastome contains 113 genes, consisting of 80 unique protein-coding genes, 29 unique tRNA gene and four unique rRNA genes (5S rRNA, 4.5S rRNA, 23S rRNA and 16S rRNA). The overall A/T content in the plastome of C. nutans is 61.60%. The complete plastome sequence of C. nutans will provide a useful resource for the conservation genetics of this species as well as for the phylogenetic studies of Acanthaceae. [ABSTRACT FROM AUTHOR]

Taxonomic and phylogenetic diversity within forest communities are influenced by many factors, but our understanding concerning diversity patterns along elevational gradients is still unclear. Though there are many studies on diversity patterns such as phylogenetic diversity (PD), there are only handful describing how altitude affects these diversity patterns, especially in the tropical forest areas of China. It has been assumed that increases in elevation can lead to gradual decreases in abundance, richness, and phylogenetic diversity. Here, we assessed these parameters in fifteen 50 × 50 m plots across various elevations (281 m–1175 m) at Diaoluo Mountain of the Hainan tropical forest in the years 2010 and 2015. Regressions between tree richness, PD, and environmental variables (climate and soil variables) were conducted to uncover the potential drivers of tree richness and PD. We found that the tree abundance, richness, and phylogenetic diversity first increased with increasing elevation, then reached maximum values at intermediate elevations, and finally decreased at the highest elevations. Tree species composition was mainly shaped by elevation (p = 0.001 < 0.005), suggesting that intermediate elevations result in an environmental screening effect due to the abundance of energy and moisture resources (i.e., high temperature and humidity), which is typical of tropical forests. We speculate that the intermediate elevations and historical disturbances shape the available species pool. Overall, our research revealed the diversity patterns of the Diaolu Mountain plants along the elevation, providing the basis for future plant protection planning, such as protecting plant species, maintaining plant habitats, and coordinating plant management in the area. • Handful studies describing how altitude affects diversity patterns in the tropical forest areas of China • Tree abundance, richness, and phylogenetic diversity were assessed across various elevations at Diaoluo tropical forest. • Tree abundance, richness and phylogenetic diversity increased at first and then decrease with increasing elevation. • The diversity pattern of the Diaoluo Mountain plants provides the basis for future plant protection planning. [ABSTRACT FROM AUTHOR]