Search Results (20)

Typhoons are major climate disturbances that significantly impact coastal ecosystems, particularly mangrove forests. This study examines the effects of typhoons on mangrove communities at different stages of recovery, focusing on how environmental factors influence carbon storage and net ecosystem exchange (NEE). Three mangrove sites were selected based on their recovery age: young, moderately restored, and mature. The results revealed that typhoons had the most pronounced effect on young mangroves, resulting in significant reductions in both above-ground and soil carbon storage. In contrast, mid-aged and mature mangroves demonstrated greater resilience, with mature mangroves recovering most rapidly in terms of community structure and carbon storage. Key factors such as wind speed, heavy rainfall, and changes in photosynthetically active radiation (PAR) contributed to carbon storage losses, particularly in young mangrove forests. This study underscores the importance of recovery age in determining mangrove resilience to extreme weather events and offers insights for enhancing restoration and conservation strategies to mitigate the impacts of climate change on coastal carbon sequestration. Full article

The focus of this study was on young populations of Kandelia obovata within a constructed coastal wetland in Haicang Bay, Xiamen, Southeast China. The objective was to systematically examine their allometric growth characteristics and carbon sequestration potential over an 8-year monitoring period (2016–2024). Allometric equations were developed to estimate biomass, and the spatiotemporal variation in both plant and soil carbon stocks was estimated. There was a significant increase in total biomass per tree, from 120 ± 17 g at initial planting to 4.37 ± 0.59 kg after 8 years (p < 0.001), with aboveground biomass accounting for the largest part (72.2% ± 7.3%). The power law equation with D²H as an independent variable yielded the highest predictive accuracy for total biomass (R² = 0.957). Vegetation carbon storage exhibited an annual growth rate of 4.2 ± 0.8 Mg C·ha⁻¹·yr⁻¹. In contrast, sediment carbon stocks did not show a significant increase throughout the experimental period, although long-term accumulation was observed. The restoration of mangroves in urban coastal constructed wetlands is an effective measure to sequester carbon, achieving a carbon accumulation rate of 21.8 Mg CO₂eq·ha⁻¹·yr⁻¹. This rate surpasses that of traditional restoration methods, underscoring the pivotal role of interventions in augmenting blue carbon sinks. This study provides essential parameters for allometric modeling and carbon accounting in urban mangrove afforestation strategies, facilitating optimized restoration management and low-carbon strategies. Full article

For a successful mangrove plantation, previous studies have proposed a small rubble mound breakwater, termed a “portable reef”, and explored the effectiveness of such reefs in terms of wave transmission. This study conducted a real-scale wave flume experiment incorporating a portable reef to assess the oscillatory behavior of young mangroves. To capture the dynamics of these young mangrove analogs—represented as elastic bodies—we employed a high-speed camera for precise tracking. A comparative analysis of the oscillatory characteristics was performed, evaluating the responses in both the presence and absence of the reef. The findings revealed several important points. First, portable reefs can effectively reduce wave heights, but they reduce plant oscillations to an even greater degree. Second, by calibrating the elastic modulus of the plant models, their oscillation behaviors can be analytically predicted. The results of our analytical model indicate that the acceleration experienced by the plants is amplified under conditions of shorter wave periods and softer stems, highlighting an increased susceptibility to damage from short-period waves, particularly in very young mangroves. Third, we identified that the conventional wave transmission formulas tend to overestimate the reduction in wave energy attributable to portable reefs, which consequently leads to an underestimation of the young mangroves’ oscillations. Based on these findings, we propose an integrated chart that combines wave transmission and plant oscillation coefficients, aimed at enhancing the design and effectiveness of portable reefs in protecting young mangroves. The insights obtained from this study will aid in the informed design of portable reefs. Full article

Mangrove ecosystems are valuable coastal ecosystems; however, studies on the diversity and functional features of their soil fungal communities during restoration are limited. In this study, we examined fungal diversity and trophic modes across mudflat, young mangrove, and mature mangrove stages. We found that Ascomycota and Basidiomycota were the dominant phyla, with saprotrophs as the most abundant trophic mode. The abundance of the major phyla and trophic modes significantly varied across restoration stages. Although fungal alpha (α)-diversity remained stable among the stages, beta (β)-diversity showed significant differentiation. Spearman’s analysis and partial Mantel tests revealed that total nitrogen and inorganic phosphorus significantly influenced the fungal α-diversity, whereas temperature and pH primarily shaped the fungal β-diversity. Total nitrogen and carbon were key factors affecting the trophic mode α-diversity, whereas total phosphorus and inorganic phosphorus were the main drivers of the trophic mode β-diversity. Variation partitioning analysis confirmed that nutrients, rather than soil properties, were the primary factors shaping fungal communities and trophic modes. Random forest analysis identified key bioindicators, including species such as Paraphyton cookei, and trophic modes such as saprotrophs, both of which were strongly influenced by soil carbon. These findings advance our understanding of fungal ecology in mangrove restoration. Full article

In China, Dolichandrone spathacea is a rare and endangered semi-mangrove plant species with an extremely small population, naturally distributed only in Zhanjiang City and the east coast of Hainan Island. Despite conservation concerns, the population status of D. spathacea has received little scientific attention. In this study, we evaluated the current status of D. spathacea on Hainan Island, China, in order to propose sustainable conservation strategies for future ecological restoration of its natural population. D. spathacea on Hainan Island can be divided into four populations. All the D. spathacea populations present a state of overall dispersion, local concentration, and occasionally sporadic existence, and they exist in geographical isolation. The young, middle, and old D. spathacea plants account for 20.42%, 66.20%, and 13.38%, respectively, indicating that the D. spathacea population on Hainan Island is declining. Furthermore, instead of temporal structure, we used diameter at breast height (DBH) to establish a static life table, draw a population survival curve, and quantify the future development trend through population dynamic analysis and time-series prediction. These results suggest that the D. spathacea population in the Bamen Gulf (Wenchang) and Qingmei Harbor (Sanya) on Hainan Island is sensitive to external disturbances and possesses two main increases in mortality rate—namely, in its juvenile and mature stages—due to competition and anthropogenic interferences, which might be the most important reasons for its endangered status. Depending on the current conditions of the D. spathacea population, we should conserve and expand mature trees in situ, preserve their germplasm resources, rehabilitate their habitats to promote provenance restoration, and conduct artificial cultivation and spreading planting in order to realize the sustainable conservation and management of D. spathacea. Full article

Mangroves rehabilitated after deforestation by commercial exploitation must be monitored to confirm that key ecosystem functions are being restored. Brachyuran crabs are conspicuous mangrove macrofauna and were selected as potential indicators of ecosystem recovery. A deforested former mangrove charcoal concession area in Ranong was rehabilitated by planting Rhizophora (1994), Bruguiera and Ceriops (1995) seedlings in single-species blocks. A second area, deforested and heavily degraded by tin mining, was rehabilitated with R. mucronata in 1985. Crabs at these sites were compared with those in a mixed-species conservation forest. Timed collections were made in 1999, 2008 and 2019 to compare crab diversity and relative abundance between sites and years. Thirty-three brachyuran crab species were recorded. Fiddler crabs (Austruca triangularis, Tubuca rosea) and the signal crab, Metaplax elegans, were most abundant, followed by sesarmid crabs (15 species). Species composition differed significantly between sites but not between the four planted tree species blocks. We propose Metaplax elegans as an indicator of ecological development in low-lying/newly formed sediments; fiddler crabs as equivalent indicators in young mangrove plantations/open forest habitats; and a diverse sesarmid community to indicate ecological functioning in older plantations/dense forests. Full article

Mangrove wetlands are hotspots of global biodiversity and blue carbon reserves in coastal wetlands, with unique ecological functions and significant socioeconomic value. Annual fine-scale monitoring of mangroves is crucial for evaluating national conservation programs and implementing sustainable mangrove management strategies. However, annual fine-scale mapping of mangroves over large areas using remote sensing remains a challenge due to spectral similarities with coastal vegetation, tidal periodic fluctuations, and the need for consistent and dependable samples across different years. In previous research, there has been a lack of strategies that simultaneously consider spatial, temporal, and methodological aspects of mangrove extraction. Therefore, based on an approach that considers mangrove habitat, tides, and a semantic segmentation approach, we propose a method for fine-scale mangrove mapping suitable for long time-series data. This is an optimized hybrid model that integrates spatial, temporal, and methodological considerations. The model uses five sensors (GF-1, GF-2, GF-6, ZY-301, ZY-302) to combine deep learning U-Net models with mangrove habitat information and algorithms during low-tide periods. This method produces a mangrove map with a spatial resolution of 2 m. We applied this algorithm to three typical mangrove regions in the Beibu Gulf of Guangxi Province. The results showed the following: (1) The model scored above 0.9 in terms of its F1-score in all three study areas at the time of training, with an average accuracy of 92.54% for mangrove extraction. (2) The average overall accuracy (OA) for the extraction of mangrove distribution in three typical areas in the Beibu Gulf was 93.29%. When comparing the validation of different regions and years, the overall OA accuracy exceeded 89.84% and the Kappa coefficient exceeded 0.74. (3) The model results are reliable for extracting sparse and slow-growing young mangroves and narrow mangrove belts along roadsides. In some areas where tidal flooding occurs, the existing dataset underestimates mangrove extraction to a certain extent. The fine-scale mangrove extraction method provides a foundation for the implementation of fine-scale management of mangrove ecosystems, support for species diversity conservation, blue carbon recovery, and sustainable development goals related to coastal development. Full article

Mangrove forests provide many ecosystem services to coastal communities and are essential in addressing climate change and coastal erosion. Unfortunately, physical pressures, including timber extraction, firewood, and land conversion to agriculture and aquaculture have threatened this ecosystem. Recognizing the reduction in mangrove coverage, mangrove plantations are widely being utilized in many countries to restore ecosystem services, including capturing and storing atmospheric carbon. However, it is still being determined whether mangrove plantations can sequester carbon as much as natural mangroves. This study investigated the carbon storage potential of the planted mangrove in the Ayeyarwady Region, Myanmar. Field data: the diameter at breast height (DBH) ≥ 5 cm and the total tree height (H) ≥ 1 m of all standing trees within each plot were measured and recorded according to species and were used to calculate biomass and carbon storage. The findings of the present study described that the overall average above- and belowground carbon storage of the mangrove plantation was 100.34 ± 50.70 Mg C ha⁻¹ and 34.76 ± 16.59 Mg C ha⁻¹, respectively. Biomass and carbon storage were closely related to the stand basal area. Among species, the Avicennia officinalis species contributed the highest total biomass carbon accumulation. The average amount of carbon sequestration by the planted mangroves was 495.85 MgCO₂-eq ha⁻¹. According to the findings, mangrove plantations could achieve benefits in terms of carbon storage and sequestration in biomass with suitable species selection and management. This finding can be applied to mangrove plantation management at the regional and global levels. Full article

Molecular oxygen and carbon dioxide may be limited for aquatic plants, but they have various mechanisms for acquiring these gases from the atmosphere, soil, or metabolic processes. The most common adaptations of aquatic plants involve various aerenchymatic structures, which occur in various organs, and enable the throughflow of gases. These gases can be transferred in emergent plants by molecular diffusion, pressurized gas flow, and Venturi-induced convection. In submerged species, the direct exchange of gases between submerged above-ground tissues and water occurs, as well as the transfer of gases via aerenchyma. Photosynthetic O₂ streams to the rhizosphere, while soil CO₂ streams towards leaves where it may be used for photosynthesis. In floating-leaved plants anchored in the anoxic sediment, two strategies have developed. In water lilies, air enters through the stomata of young leaves, and streams through channels towards rhizomes and roots, and back through older leaves, while in lotus, two-way flow in separate air canals in the petioles occurs. In Nypa Steck palm, aeration takes place via leaf bases with lenticels. Mangroves solve the problem of oxygen shortage with root structures such as pneumatophores, knee roots, and stilt roots. Some grasses have layers of air on hydrophobic leaf surfaces, which can improve the exchange of gases during submergence. Air spaces in wetland species also facilitate the release of greenhouse gases, with CH₄ and N₂O released from anoxic soil, which has important implications for global warming. Full article

Mangroves are typically found in tropical coastal areas, and these ecosystems face deterioration and loss due to threats from climate and human factors. In this study, sediment cores were collected from human-planted mangroves in sub-tropical Ximen Island, China, and were determined for sedimentary phosphorus (P) species. The objective was to investigate the ability of mangroves planted in a zone bordering their temperature limit to preserve and regulate P. Our results showed that bioavailable P (BAP), which includes exchangeable-P (Ex-P), iron-bound P (Fe-P), and organic P (OP), accounted for approximately 64% of total P (TP). Apatite P (Ca-P), which accounted for 24% of TP, most likely originated from aquaculture activities surrounding the island. The vertical distribution of sedimentary P species along the sediment cores showed a rather constant trend along the salt marsh stand but considerable fluctuations for the mangroves and bare mudflat. These results indicate that mangroves accumulated P when there was a high P discharge event, and that this P was eventually released during organic matter decomposition and contributed to Ca-P formation. Nevertheless, old and young mangroves accumulated higher sedimentary P species, OP, and BAP compared to the salt marsh stand and bare mudflat areas. This study showed the potential of mangroves planted outside their suitable climate zone to preserve and regulate P. Full article

The sustainability of mangrove ecosystems requires a knowledge of their spatiotemporal variability as a function of regional properties. The unique coastal ecosystems of the mangrove belt along the coast of the Guianas in South America are influenced by cycles of a massive accretion of mud supplied by the Amazon River and wave induced erosion. This study characterized, for the first time, how benthic infaunal assemblages, as proxies of mechanisms of mangrove resilience, were structured by the natural growth track of Avicennia germinans dominated mangroves in French Guiana. We sampled 4 mobile mud stations and 27 consolidated mud stations distributed over 9 tidal transects from bare to vegetated mudflats colonized by young mangroves during the dry season. We collected a complete dataset of sediment and vegetation variables together with the benthic meso- (>0.25 mm) and macrofauna (>1 mm). We used a combination of eigenvector based multivariate analyses and variance partitioning on this multiple set of variables to identify which environmental variables likely drive the benthic diversity patterns. Mangrove early development increased the alpha and beta diversities of the infaunal communities for the two size classes. A total of 20–30% and 7–12% of the beta diversity are explained by linear and nonlinear spatial variables, respectively. However, 7% to 9% of the variance partioning could be determined by other biotic/abiotic variables, biological interactions or neutral processes, not described here. This study has highlighted the necessity of taking into account mangrove dynamics at suitable spatial scales for benthic biodiversity evaluation and mangrove management or restoration plans. Full article

Over the past 30 years, 30–40% of the world’s mangroves have been lost and continue to be lost to deforestation. In recent years, mangrove rehabilitation projects have increased, replacing once natural and diverse mangrove forests with monotypic stands (e.g., Rhizophora mucronata). However, the vulnerability to sea level rise of these artificial stands and their effectiveness at providing ecosystem services is unclear. To address these gaps, we compared the rate of sediment surface elevation change and contemporary soil C sequestration across three differently aged mangrove plantations (5, 10, 25 years) in relation to a natural mangrove forest in Quezon province, Philippines using rod surface elevation tables (rSETs) and soil C analyses. Over a 3-year period, we found that the elevation of the 5-year-old plantation had the highest rate (6.12 mm year⁻¹), followed by 10-year-old (1.70 mm year⁻¹) and 25-year-old (0.16 mm year⁻¹) plantations, while the natural stand had a decreasing rate (−1.9 mm year⁻¹). In addition, the mean soil carbon contemporary sequestration rate was 226, 123, and 8.9 g C m⁻² year⁻¹ for the 5-, 10-, and 25-year-old plantations. Old mangroves have bigger carbon stocks, whereas young mangrove plantations are more resilient to SLR and have higher contemporary carbon sequestration rates. Except for biomass and basal area, we found no correlation of the sediment elevation change and soil C sequestration rates with other stand variables. Apart from the 5-year-old plantations, the rates of sediment elevation change obtained are less than the global (3.2 mm year⁻¹) and local (2–4 mm year⁻¹) rates of sea level rise (SLR). These suggest that most of the forested coastal wetlands studied are not keeping pace with SLR and may potentially drown if there is no available land behind them to retreat. This also indicates that pro-active solutions such as strict protection must be made. Full article

Mangroves are highly productive blue carbon ecosystems that preserve high organic carbon concentrations in soils. In this study, particle size, bulk elemental composition and stable carbon isotope were determined for the sediment cores collected from the landward and seaward sides of two mangrove forests of different ages (M1, ca. 60; M2, ca. 4 years old) to determine the effects of geomorphic setting and age (L1 = old mangrove and S1 = salt marsh stand in M1; L2 = young mangrove and S2 = bare mudflat in M2) on sediments and organic carbon accumulation. The objective of this study was to determine the feasibility of the northernmost human-planted mangroves in China to accumulate sediment and carbon. Our results showed that fine-grained materials were preserved well in the interior part of the mangroves, and the capacity to capture fine-grained materials increased as the forest aged. The biogeochemical properties (C/N: 5.9 to 10.8; δ¹³C: −21.60‰ to −26.07‰) indicated that the local organic carbon pool was composed of a mixture of autochthonous and allochthonous sources. Moreover, the accumulation of organic carbon increased with the forest age. The interior part of the old mangrove had the highest organic carbon stock (81.93 Mg C_org ha⁻¹). These findings revealed that mangrove reforestation had positive effects on sediments and organic carbon accretion. Full article

Mangrove forests have declined worldwide and understanding the key drivers of regeneration at different perturbation levels can help manage and preserve these critical ecosystems. For example, the Ramsar site # 1602, located at the Tampamachoco lagoon, Veracruz, México, consists of a dense forest of medium-sized trees composed of three mangrove species. Due to several human activities, including the construction of a power plant around the 1990s, an area of approximately 2.3 km² has suffered differential levels of perturbation: complete mortality, partial tree loss (divided into two sections: main and isolated patch), and apparently undisturbed sites. The number and size of trees, from seedlings to adults, were measured using transects and quadrats. With a matrix of the abundance of trees by size categories and species, an ordination (nMDS) showed three distinct groups corresponding to the degree of perturbation. Projection matrices based on the size structure of Avicennia germinans showed transition probabilities that varied according to perturbation levels. Lambda showed growing populations except on the zone that showed partial tree loss; a relatively high abundance of seedlings is not enough to ensure stable mangrove dynamics or start regeneration; and the survival of young trees and adult trees showed high sensitivity. Full article

Despite all efforts and massive investments, the restoration of mangroves has not always been successful. One critical reason for this failure is the vulnerability of young mangroves, which cannot grow because of hydrodynamic disturbances in the shallow coastal water. For a comprehensive study bridging ecological and engineering principles, a portable community-based reef is proposed to shield mangroves from waves during the early stages of their growth. A series of field observations were conducted on Amami Oshima Island (Japan), to observe the growth of young mangroves and their survival rate under moderate wave conditions. The evolution of young mangroves was also observed in the laboratory under a controlled indoor environment. At the research site, it was confirmed that, after six months of germination, young mangroves could withstand normal high waves. Laboratory-grown plants were lower in height and had fewer leaves compared with the native mangroves on Amami. Based on these results, an economical reef system was designed. For this purpose, the Ahrens formula for the design of a low-crested reef breakwater was revisited. The results showed that a 50-cm-high reef constructed with 15-kg stones can protect mangroves that are a few months old and effectively promote early mangrove growth. Full article