Seawalls are widely constructed to protect coastal communities and infrastructure against storm surges and tidal flooding; however, they often exert significant ecological pressure on adjacent wetland ecosystems. Understanding these impacts is critical for sustainable coastal management, particularly in the context of intensifying coastal squeeze. In this study, we investigated the effects of seawall construction on benthic mollusk communities within subtropical mangrove wetlands by comparing assemblages in mangroves fronting seawalls with those in adjacent, undisturbed natural mangroves. The results showed that species richness at the plot scale did not differ significantly between the two habitats (p > 0.05), highlighting the potential limitations of relying solely on species counts for ecological assessment. Conversely, Shannon and Simpson diversity indices were significantly higher in natural mangroves. Notably, two common species of Ellobiidae were entirely absent from seawall-fronted sites despite their consistent presence in the natural reference habitats. These findings suggest that ellobiid snails may serve as effective indicator species for evaluating the ecological footprint of seawall construction. Broadly, our results underscore the necessity of incorporating multi-dimensional diversity metrics, particularly those capturing abundance distributions, alongside indicator taxa to ensure robust biodiversity assessments.

Aim Although positive aboveground-belowground biodiversity linkages are well-established, these relationships are context-dependent in natural communities, particularly in highly dynamic ecotones like mangrove ecosystems where plant-animal interactions remain poorly understood. This study aims to elucidate the complex relationship between plant and mollusc diversity in mangrove ecosystems, challenging the conventional paradigm that higher plant diversity invariably promotes faunal diversity. We focus on investigating how environmental factors mediate these relationships. Location Mangrove forests of Hainan Island, China—a representative tropical wetland system exhibiting conspicuous east-west plant-mollusc diversity mismatches. Methods A multi-model approach (random forests, linear regression, and structural equation modeling) was used to analyze cross-shore diversity patterns, incorporating climatic, sedimentary, and landscape drivers along eastern (high-plant/low-mollusc) and western (low-plant/high-mollusc) coasts. Results (1) Significant east-west divergence: the eastern coast had significantly higher plant richness but lower mollusc richness than the western coast; (2) Salinity as critical mediator: plant richness enhanced mollusc diversity indirectly by reducing interstitial water salinity; (3) Environmental threshold effects: stronger negative plant-mollusc correlations occurred under low-stress conditions (average annual temperature < 24.8 °C, aridity index < 0.8, interstitial water salinity < 1.8%). Main Conclusions This study quantified threshold effects in mangrove plant-animal relationships along environmental gradients. We propose a novel zone-specific conservation strategy: prioritizing vegetation protection on the eastern coast while emphasizing mollusc conservation on the western coast. These findings provide both theoretical foundations and practical pathways for precision management of mangrove ecosystems, offering valuable insights for coastal wetland conservation in the region.

Abstract Stomata regulate plant gas exchange, photosynthesis, and transpiration. Their spatial distribution is an important functional trait, but most studies are limited to microscopic fields of view that cover only a small part of the leaf surface. Here, we present a simple scanner-based approach for mapping stomata at the whole-leaf scale. Using a 4800-dpi (189 pixels mm-1) scan of a Sonneratia apetala leaf, we identified 48,772 stomata across 645 mm2 and generated a whole-leaf stomatal distribution map. We validated scanner-derived stomatal locations against light microscopy using 853 matched stomata. Pairwise distances derived from the two methods showed strong agreement, with an R2 = 0.983. This method provides a low-cost and accessible way to map stomatal abundance, density, and spatial distribution in leaves with suitable epidermal features. We also developed a preliminary semi-automated workflow for candidate stomatal detection and localization. We emphasize that this approach is not designed to measure stomatal area, guard-cell size, or pore aperture, and that it should be validated with microscopy before use in new species. Although the method is not suitable for all leaf types, this scanner-based framework can extend stomatal research beyond local microscopic observations and support future studies of leaf functional traits.

Mangrove ecosystems are vulnerable to extreme events and sea-level rise. The present study examined how biological and geomorphological processes interact at mangrove seaward margins (MSM) using remote sensing, field surveys, and elevation monitoring from 2009 to 2021 in northeastern Hainan, China. The results showed that the mangrove edge had retreated by 11.04 ± 0.36 m. Retreat was more rapid in heavily disturbed areas, especially during 2013-2017 when intense tropical cyclones occurred. In these areas, edge seedling recruitment of Rhizophora stylosa declined, with establishment probability being strongly influenced by surface elevation. Mature trees exhibited increased root damage and reduced leaf chlorophyll content, with trait variation primarily driven by surface elevation and sediment physical properties. Following vegetation dieback, surface elevation declined rapidly, forming a positive biogeomorphic feedback that further inhibited regeneration and accelerated margin degradation. We identified a feedback loop between vegetation loss and geomorphic change triggered by extreme disturbances at the MSM that limits natural recovery and threatens ecosystem stability. Our findings underscore the need to prioritize monitoring edge zones and suggest a management framework that integrates remote sensing with in situ monitoring to identify vulnerable zones and guide post-disturbance conservation and restoration under increasing environmental stress.

The expansion of exotic Spartina alterniflora has created novel ecotones with native mangroves along China’s southeastern coast. While interactions are often viewed as static competition, the historical assembly processes remain poorly understood. In this study, we conducted a retrospective analysis using high-resolution time-series satellite imagery from Sentinel-2 and Google Earth to reconstruct the co-occurrence dynamics of S. alterniflora and native mangroves in a subtropical estuary. We quantified saltmarsh coverage prior to mangrove colonization and applied logistic regression to assess the relationship between mangrove establishment probability and saltmarsh density. Our results show that mangrove colonization is significantly negatively associated with local saltmarsh density. Mangroves establish preferentially in S. alterniflora gaps within the saltmarsh, as indicated by a statistically significant negative association between mangrove establishment probability and saltmarsh density (P < 0.001). These results highlight the importance of historical context, because reliance on a single temporal snapshot can lead to misleading inferences. Inspired by these findings, we propose a management framework centered on assisted natural regeneration rather than total eradication. Our findings suggest that strategic thinning or the creation of vegetation gaps could help reduce the biotic resistance imposed by S. alterniflora. When combined with the planting of native mangrove seedlings, this approach may facilitate the gradual replacement of the exotic saltmarsh by native mangroves. More broadly, the strategy has the potential to provide a resource-efficient and ecologically sustainable pathway for coastal restoration by retaining some of the geomorphic benefits associated with the invasive species while supporting the recovery of native biodiversity.

Coastal pond-to-mangrove restoration has become a prominent Nature-based Solution, yet its short-term ecological effects on waterbird communities remain unclear. We assessed taxonomic, functional, and compositional responses of waterbirds to large-scale restoration in Bamen Bay, Hainan Island, using BACI-style comparisons between restored and unrestored aquaculture ponds in 2021 and 2023. Restored areas exhibited higher taxonomic α diversity and functional richness (p < 0.001), coinciding with rapid habitat diversification following hydrological reconnection. Species richness (p < 0.001), Shannon diversity (p < 0.01), and functional richness (p < 0.01) were consistently higher in restored areas than in aquaculture ponds. In contrast, β diversity patterns diverged between habitats: restored areas remained relatively stable, whereas aquaculture ponds showed greater between-year compositional change (p < 0.05). Guild-specific responses revealed contrasting patterns: herons showed higher diversity in restored habitats (p < 0.05), whereas shorebirds exhibited no significant changes (p > 0.05), consistent with their dependence on open mudflats that were only partially retained. Although no significant declines were detected, functional richness tended to be lower in 2023 (p > 0.05), and ongoing mudflat loss suggests potential long-term risks for mudflat specialists, warranting extended monitoring. Taken together, our findings suggest that effective pond-to-mangrove restoration in Bamen Bay should balance mangrove expansion with the retention of tidal flats and managed shallow-water habitats to support diverse waterbird assemblages.

Major biodiversity changes in the Anthropocene demand enhanced monitoring of ecological communities. Notably, community-level attributes of coastal wetland ecosystem engineers, especially crabs (Brachyura), emerge as crucial ecological indicators. However, traditional expert-based surveys for such data remain labor-intensive, time-consuming, and often invasive. This creates an urgent need for an automated and efficient paradigm shift. We developed an RGB sensor-based automated framework and collected extensive image data from 17 coastal mangrove wetlands across China. This framework integrates expert knowledge with artificial intelligence via a pyramid-style annotation approach, utilizing optimized CNN models (YOLOv5/v8 and EfficientNet) for automated image processing and indicator extraction. Test results show that by integrating attention modules and improved anchors, our model achieved superior performance in crab detection, classification, carapace width measurement, biomass estimation, and burrow detection, matching or exceeding manual methods. It further captured plot-level spatial point patterns, addressing limitations of conventional manual surveys. Our local case study validated that image-extracted community metrics provide independent and essential insights for community analysis, offering a more efficient and comprehensive indicator system than traditional methods. Ecologically, this deep learning-integrated novel method provides an economical solution to expand the dimensionality and breadth of biological data. It enhances management effectiveness by (1) serving as foundational hardware-software for in-situ monitoring and automated data collection (scalable to other benthic fauna), and (2) capturing higher-dimensional community indicators and fine-scale spatial patterns to support biodiversity conservation, blue carbon sequestration, and vegetation protection.

In Luoyuan Bay, China, Sporobolus alterniflorus invasion has hindered mangrove restoration and disrupted faunal communities within mangrove habitats. This study investigated its impact on mollusk, crab, and fish assemblages across mangrove, mudflat, and invaded habitats from 2019 to 2020. Results showed that species diversity of three assemblages did not differ significantly between invaded and non-invaded mangrove habitats; however, assemblage structure was altered and functional traits declined markedly in invaded areas. Compared with non-invaded mangroves, invaded habitats showed decreases of 81.6% in mollusk density, 50.7% in mollusk biomass, 66.6% in crab density and 84.2% in crab biomass. Dominant fish species (Acanthogobius ommaturus, Liza carinata, Stolephorus chinensis) also exhibited lower body size, total size and biomass in invaded habitats. Given the close dependence of coastal residents on these faunal resources, a socioeconomic analysis of livelihood strategies was conducted, revealing Sinonovacula constricta aquaculture achieved the highest net income-to-investment ratio, 122.7% higher than nearshore fishery and 308.3% higher than shallow-sea oyster cultivation, while professional shellfish farming yielded the highest net income per hectare, 23.6% higher than oyster cultivation. Thus, both forms of shellfish aquaculture provide greater economic returns than other livelihood options. Based on these findings and niche theory, we propose a management framework: after removing S. alterniflorus, plant native mangroves (Kandelia obovata) in mid-to-high intertidal zones and lease lower flats for shellfish farming. This framework has the potential to integrate ecological restoration with local livelihoods and may inform similar efforts in other regions facing biological invasions and restoration challenges.

In estuarine and coastal ecosystems, the freshwater-saltwater interface serves as a core zone for land-sea interactions. The mangrove-stream ecotones within this interface exhibit highly dynamic microenvironmental differentiation through synergistic salinity-topography gradients. However, the multidimensional biodiversity drivers regulating macrobenthos community assembly within these dynamic transition zones remain critically underexplored. This study investigated macrobenthos community assembly across mangrove wetlands and five estuarine streams in Fuding, China. By integrating diversity indices with multivariate modeling, we compared spatial differentiation patterns and environmental drivers. Results indicated that mangroves supported significantly higher α-diversity, functional richness, and redundancy than streams, which exhibited higher functional vulnerability. While taxonomic β-diversity in both ecosystems was predominantly driven by species turnover, mangroves exhibited significantly higher functional β-diversity than streams, which were characterized by low functional turnover and high structural instability. Dissolved oxygen, salinity and elevation were identified as key environmental factors driving the structure of mangrove communities. In contrast, stream communities primarily responded to salinity, elevation and pH gradients. These differences confirmed the interplay between salinity and topographic factors. Consequently, we established a differentiated management framework. Mangrove conservation requires the maintenance of heterogeneous habitats with a tidal-elevation gradient in order to enhance functional redundancy. Stream conservation should involve the regulation of salinity fluctuations and the increase of functional turnover rates. This ultimately strengthens the resilience of the interaction zone. This study establishes the first regional-scale macrobenthic indicator system for mangrove-stream ecotones, providing a scientific basis for adaptive coastal management under global change.

Bergenia purpurascens is an important medicinal, edible, and ornamental plant. It generally grows in extreme environments with complex stresses. The GRAS transcription factors play a crucial role in regulating plant stress tolerance and growth-development. There is no research on GRAS transcription factors in B. purpurascens. In this study, 29 B. purpurascens GRAS (BpGRAS) genes were identified based on B. purpurascens transcriptome data. These BpGRAS genes were classified into seven subfamilies according to phylogenetic analysis, while BpGRAS1 was not classified into any other subfamilies. The motif analysis showed that the protein motifs in the same subfamily were relatively conserved. The expression pattern analysis of BpGRAS genes in different tissues and under salt stress showed that eight BpGRAS genes were differentially expressed under salt stress. The expression profiles showed that BpGRAS9 might play an important role in salt response and the transgenic Arabidopsis thaliana lines with overexpressed BpGRAS9 showed the enhanced salt tolerance. Root length and fresh weight were significantly increased in transgenic lines under salt conditions. The studies enhanced our comprehension of the function of BpGRAS and established a more foundation for exploring the molecular mechanisms underlying plant salt tolerance.

Vivipary is common in several mangrove species and is generally considered an adaptation to the intertidal saline environment. However, the coexistence of many nonviviparous mangroves makes this view controversial. This study investigated the propagule development of two nonviviparous mangrove species, Sonneratia alba and S. caseolaris, with marked differences in salt tolerance and distribution. Changes in the density, water content, and concentrations of the five main osmoregulatory elements (Cl, Na, K, Ca, and Mg) were determined. As the propagules of S. alba and S. caseolaris mature, the element concentrations (mg/g) in the propagules gradually decrease, indicating a desalination process. Moreover, the Cl, Na, Ca, and Mg content in the propagules were lower than in the mature leaves and calyx. Similar to viviparous mangroves, the development of the propagules of nonviviparous mangroves is also a desalination process. Although both viviparous and nonviviparous mangrove species undergo a desalination process during propagule development, our findings suggest that viviparity may not be solely defined by desalination, but rather by the extended period of low-salinity protection during early development on the maternal tree, which represents a key adaptation for survival in high-salinity environments. In contrast, nonviviparous mangroves, which rely on seed germination and early development in saline seawater, face additional challenges in high-salinity habitats, highlighting their distinct adaptive strategies.

Understanding biodiversity patterns across multiple taxonomic groups is crucial for effective conservation planning to address the rapid global decline in biodiversity. While mangrove plant diversity has been extensively studied, the associated fauna, particularly benthic animals, have received insufficient attention. In this study, we compiled a dataset of mangrove benthic mollusks based on field surveys, including 27,610 individuals representing 160 species across 10 natural reserves. We also included the corresponding mangrove plant species lists from field surveys and species inventories for each reserve on tropical Hainan Island, China. We analyzed the relationship between mollusk diversity and mangrove plant species richness. Results show no consistent alignment between plant and mollusk diversity, with non-significant Spearman correlation coefficients (P > 0.1). Furthermore, five out of ten sites exhibit either below-average mollusk diversity with above-average plant diversity or below-average plant diversity with above-average mollusk diversity. This suggests that plant diversity is not a reliable surrogate for mollusk diversity, and vice versa. These mismatches complicate conservation planning, as protecting a single site cannot ensure multi-taxon biodiversity. We recommend that the design of protected areas and conservation assessments include multiple taxonomic groups. In mangrove ecosystems, monitoring plant diversity alone is insufficient, and other groups, such as the mollusks examined in this study, should also be considered.

Coastal regions, as a hotspot region of biodiversity and the most densely populated areas in the world, are increasingly threatened by anthropogenic disturbances, including warming, acidification, eutrophication, salinity fluctuation, and oxygen loss. Although massive single-factor studies have revealed the ecological catastrophe caused by these impacts, how these impact stressors interact to endanger coastal biodiversity that is critical for ecosystem stability and human well-being is still poorly understood. To investigate whether and how water warming, acidification, eutrophication, salinity fluctuation and oxygen loss interact with each other to impact the mangrove mollusk diversity, a long-term study was conducted in the mangroves of Chinese Daya Bay from 1987-1993 to 2017-2021. We found that water temperature, chlorophyll-a, total nitrogen (TN) and total phosphorus (TP) increased significantly, while the water pH, salinity, dissolved oxygen (DO) and mollusk species richness decreased obviously, reflecting water warming, eutrophication, acidification, salinity fluctuation, oxygen loss and biodiversity loss occurred in the Daya Bay. The mangrove mollusk diversity had a significant response to the water warming, eutrophication, acidification, salinity fluctuation, oxygen loss (p < 0.001). The average incidences of mollusk diversity loss due to the changes in water pH, temperature, TP, TN, chlorophyll-a, salinity and DO were 47.11 %, 35.56 %, 35.53 %, 34.48 %, 34.22 %, 34.15 % and 33.05 %, respectively. Moreover, the average effect of interactions between any two water factors on the mollusk diversity was 0.998, which was 22.5 % larger than their single effect on biodiversity of 0.814. The findings suggest that interactions between global change stressors can exacerbate biodiversity loss in coastal wetlands. Quantifying those effects in terms of multi-factor interactions will contribute to the coastal management and restoration based upon combined evidence rather than a one-sided single perspective.

Tropical coral island vegetation poses formidable challenges, particularly in elucidating the determinants of vegetation species richness. In response, our study compared the differences in plant species biodiversity and soil physicochemical properties on seven adjacent coral islands at different stages of vegetation succession, from bare land to 100% vegetation coverage in the South China Sea, all of which were less than 0.3 km 2 . Contrary to the established island ecological theories, our results indicated that soil nutrients significantly govern the species diversity of tropical coral islands. However, the timing of soil development, island area, distance from larger islands, and island altitude were not significantly correlated. Cluster analysis showed that the diverse islands of Qilianyu Island (Seven Sisters) represent distinct stages of tropical coral island succession: pioneer vegetation, shrub and grass communities, and coral island forest vegetation. As island vegetation underwent succession, plant species increased from 6 to 57, and organic carbon, total nitrogen, and available phosphorus content significantly increased, accompanied by increasing salinity and decreasing pH. Our findings revealed a nested structure in the vegetation of tropical coral islands, primarily dominated by environmental filtering on a small scale, at least on Qilianyu Island. This indicates that the restoration of damaged island vegetation can begin with soil rehabilitation. We contend that improving soil nutrient conditions and development status contribute to the establishment of island vegetation, with careful consideration of interspecific combinations that expedite the restoration process on tropical coral islands. This study addresses the lack of clarity surrounding the determinants of vegetation species richness on tropical coral islands, thus providing a novel perspective grounded in soil nutrient‐driven succession.

Tidal inundation is a key environmental factor in coastal wetland ecosystems, such as mangroves. Understanding the response of mangroves to increased flooding stress under rising sea levels is crucial in the context of rapid global climate change. While previous studies have focused on the mangrove seedlings in controlled experiments, field studies on the response of mature mangrove trees to rising sea levels remain limited. This study examines the impact of flooding stress caused by tidal inlet narrowing on mangroves in a tropical microtidal estuarine lagoon on Hainan Island, China. We assessed the mortality of four common mangrove species: Avicennia marina, Ceriops tagal, Rhizophora apiculata, and Scyphiphora hydrophyllacea, and conducted an elevation gradient survey of C. tagal in two transects to evaluate how different mangrove species respond to flooding stress. The average tree heights of these species were 1.79 m, 1.16 m, 3.14 m, and 2.38 m, respectively, with survival probability after the flooding event of 42%, 12%, 89%, and 95%, respectively. We found that survival probability was positively related to tree height across the four species (P < 0.001), and the site elevation of C. tagal is significantly positively associated with survival probability (P < 0.001). Additionally, higher elevations correspond to better health in surviving C. tagal, indicated by more live leaves per twig and a higher leaf Fv/Fm ratio (P < 0.001). These results suggest two mortality patterns in mangrove responses to the extreme flooding event: tree height-based and elevation-based mortality. The ordered mortality implies that mangrove vulnerability to sea- level rise is heterogeneous. These findings imply that future assessments of mangrove vulnerability should consider the fine-scale spatial distribution of species and the spatial heterogeneity of tree height.

Mangrove wetlands are naturally divided into habitat patches by tidal creeks, with patch edges highly vulnerable to human activities and biological invasions, making them critical areas for mangrove degradation. Understanding the geometrical characteristics of these patches is essential for mangrove management in the Anthropocene, yet their exploration remains limited. Using a high-resolution (2 m) mangrove distribution dataset from 2018, we analyzed the patch structure of mangroves in southern China. This study revealed predominantly small and elongated patches, with an average area of 0.044 km2 and a median of 0.011 km2 across 5857 patches. About 65% of patches had a major-axis length over twice their minor-axis length. The patch number and area peaked between 19° N and 22° N. The patch number and area peaked between 19° N and 22° N. In the 0.1° × 0.1° latitudinal-longitudinal grid, the maximum mangrove area was 9.03 km2, consisting of 192 patches. Additionally, the patch composition and geometric characteristics differed significantly among the existing reserves. These findings highlight the need to prioritize the patch geometry in management strategies, especially in regions with numerous small patches prone to degradation and invasion. Additionally, this study underscores a critical research gap: the ecological impacts of mangrove fragmentation on biodiversity and ecosystem services remain poorly understood. Future research should focus on how the patch structure and landscape configuration influence ecological processes in mangrove wetlands.

The raindrop size distribution (DSD) reflects the size distribution of raindrop particles and is of great significance for studying the microphysical processes of precipitation and improving the accuracy of quantitative precipitation estimation. In this study, eight years of disdrometer data were used to analyse the characteristics of the DSD at different geographical locations (the island station ISL and the inland plain station INL) in eastern China to explore its geographical distribution characteristics. The results show that the peak values of N(D) at the ISL and INL stations appear at 0.56 mm and 0.69 mm in diameter, respectively. The ISL station has a higher N(D) for small particles and a lower N(D) for large particles. In terms of convective precipitation, the ISL station tends to be more maritime-like, while the INL station is more continental-like. In addition, the μ-Λ relationships obtained in this study indicate that for the same Λ, the μ value at the ISL station is less than that at the INL station. The diameters of most particles at the two stations are between 1 and 2 mm, and the range of μ values at the ISL station is larger. For stratiform (convective) precipitation, the Z-R relationships at the ISL and INL stations are Z = 255.2R1.515 (Z = 133.7R1.641) and Z = 298.8R1.545 (Z = 206.4R1.551), respectively, indicating that the Z-R relationships mainly depend on the precipitation type rather than the region. In INL, the collisional breakup process is more prominent, with approximately 17% of DSDs reaching EDSD, compared to only 10% at ISL.

Mangrove restoration is critical for the resilience of coastal ecosystems, yet there remains insufficient research on the ecological effects of artificial versus natural restoration, especially regarding their impacts on faunal communities and ecosystem functions. This study used a space-for-time substitution approach to investigate the taxonomic and functional diversity of crab communities along a 27-year pond-to-mangrove restoration chronosequence in Dongzhaigang Bay, southern China. We analyzed temporal changes in community composition and functional traits under artificial and natural restoration approaches, compared alpha diversity and the components of beta diversity across sites, and explored the influence of environmental variables on variations in crab community structure. A total of 3,700 crabs representing 24 species were recorded. Artificial restoration sites exhibited rapid early colonization, with species richness reaching 1.5 times that of natural restoration sites by year 4. However, by year 27, both artificial and natural restoration sites showed no significant differences in crab taxonomic and functional diversity compared to natural mangroves. The results indicate that species composition in both restoration types underwent a typical successional process, beginning with dominance by filter-feeding Ocypodidae crabs in the early stages and gradually shifting to dominance by herbivorous and omnivorous crabs of the Grapsoidea family in later stages. Nevertheless, the proportion of functional groups in naturally restored sites was closer to that of natural mangroves. Soil pH and salinity were identified as the primary environmental drivers shaping both taxonomic and functional community patterns. Based on these findings, we emphasize the importance of incorporating functional traits and successional dynamics alongside taxonomic metrics to more accurately assess the ecological recovery of mangrove restoration efforts.

Afforestation of mangroves in abandoned ponds is considered an effective approach for global mangrove restoration. Although several studies have assessed recovery outcomes of reforested mangroves, the studies about the synergistic recovery of mangrove vegetation and ecosystem carbon stocks in abandoned ponds are still limited. The present study compared the vegetation structure and carbon stocks of pond-to-mangrove sites with different restored methods in Dongzhaigang Bay, Hainan Province, China. We found that the vegetation structure (tree density and Shannon diversity) had no significant differences between afforestation sites and natural mangroves. The total ecosystem carbon stocks of all the sample sites ranged from 64.07 to 224.91 (mean +/- SD: 114.82 +/- 49.30) Mg C ha(-1), while there were no significant variations between restoration sites in 2014 (p > 0.05). In addition, 85.44 % of the total carbon stocks were stored in the soil among the study sites. The soil physicochemical properties such as soil pH, total organic carbon, total nitrogen had effects on tree height, diameter at breast height and carbon stocks composition. Meanwhile, in-situ soil redox potentials, Shannon diversity, tree height, density and diameter at breast height affected carbon stock. Moreover, the soil physicochemical properties, absolute elevation and vegetation structural variables could explain 76.83 % of the carbon stock variance. This study demonstrated that artificial planting had no superiority in vegetation restoration and carbon sequestration over natural regeneration. Under appropriate environmental conditions, natural regeneration is an economically effective way to restore mangroves from abandoned ponds to realize the co-benefits of biodiversity and carbon storage restoration.

On July 18, 2014, Super Typhoon Rammasun caused significant damage to a mangrove forest at Dongzhaigang Bay, Hainan Island. To evaluate the structural damage and recovery patterns of mangrove forests, vegetation in permanent plots was surveyed at 1, 12, and 24 months after the event. Six mangrove species were assessed, including five native species (Kandelia obovata, Bruguiera sexangula, Rhizophora stylosa, Avicennia marina, and Ceriops tagal) and one exotic species (Sonneratia apetala). Results revealed that mangroves exhibited species-specific resistance and resilience to the super typhoon. S. apetala and B. sexangula were the most severely affected, followed by K. obovata, R. stylosa, and A. marina. C. tagal was the least impacted, indicating its high resistance. The extent of damage at community level had a significant positive correlation with basal diameter and tree height, and a negative correlation with the tree density. S. apetala, A. marina, and R. stylosa displayed rapid recovery after the event, indicating their high resilience. However, B. sexangula and K. obovata had notably high mortality one year after the disturbance. Species traits (e.g. refoliation or resprouting) interact with environmental factors such as changes in hydrology in producing post-hurricane recovery patterns. Damage and recovery from storms varies among species indicating that diverse assemblages are important for sustainability of projects using mangroves as nature-based solutions under a changing climate with increasing storm strength and frequency.