Coastal shelterbelts perform significant ecological functions but are harsh and fragile habitats where plant diversity is seriously constrained by environmental stressors. However, the complex interactions among soil environmental conditions, plant communities, and ecosystem stability, as well as the underlying mechanisms, remain poorly understood, limiting the development of effective conservation strategies. To address this, we surveyed 30 representative sandy coastal shelterbelts of Guangdong Province in southern China, identifying 118 vascular plant species, dominated by Casuarina equisetifolia, Bidens pilosa, and Brucea javanica. Based on soil properties, the sites were classified into three distinct environmental groups (G1, G2, and G3). Specifically, G3 exhibited higher salinity and nutrient content than G1 and G2, while G1 showed the highest bulk density and G2 had the highest pH. Habitats with higher nutrient and salinity levels (G3) demonstrated greater species richness (18.67 vs 10.77, 9.36), functional richness (0.046 vs 0.026, 0.020), and community stability (0.30 vs 0.23, 0.21) than G1 and G2. In contrast, nutrient-poor habitats (G1 and G2) exhibited a higher leaf length-to-width ratio (9.91 and 14.27) than G3 (5.07) and favored stress-adaptive traits such as hairless, linear-shaped leaves. Further analysis revealed that soil environmental factors positively influenced functional traits and species diversity, which positively influenced functional diversity and community stability. This study provides new insights into the resource buffering and compensation, stress-adaptive leaf trait selection, and diversity-mediated stability mechanisms in coastal ecosystems. These findings further inform targeted restoration strategies for sandy coastal shelterbelts in Guangdong and offer a valuable framework for their management.

Macrobenthic bioturbation is vital to facilitate nutrient turnover in estuarine ecosystems and drives spatial heterogeneity in the sediment matrix. In this study, we compared the sediment physico-chemical properties, microbial community structure and functional genes in vertically-stratified sediment samples from bioturbated (burrows of Parasesarma bidens and Tubuca arcuata) and non-bioturbated area in mangrove ecosystems (the Hanjiang River Estuary, Southern China). The result indicated that bioturbation by P. bidens and T. arcuata had significantly different effects on sediment properties, with the action of P. bidens enhancing nutrient accumulation while T. arcuata promoted N2O emission. Burrow microhabitats harbored distinctive microbial communities although the dominant phylum and genera shared considerable similarity with the control sediment surface with Woeseia dominating in vertical profiles across different habitats. Co-occurrence network analysis revealed that crab bioturbation promoted formation of less complex but more functionally-specialized microbial communities. Crab bioturbation enhanced nutrient metabolism and separated clusters in dendrogram demonstrated the species-specific effect between P. bidens and T. arcuata. Our work verified the significance of bioturbators in regulating biogeochemical processes and highlighted the species-specific bioturbation effect between two dominant mangrove crabs (P. bidens vs. T. arcuata).

Natural habitat loss caused by wetland reclamation is one of the most important causation for waterbird decline worldwide. Measurements of biodiversity loss always relied on the species and abundance reduce initially. The main challenge faced by many researchers and managers is how to detect biodiversity loss before (without) species diversity decreases. Our program explored three dimensions of diversity, namely taxonomic diversity, phylogenetic diversity, and functional diversity, of waterbird at coastal lagoon, a typical waterbird habitat, with two degrees of reclamation. Based on our complete waterbird assemblage censuses at the South China coastal lagoons, we fitted mixed liner models to determine the relationships between waterbird assemblage diversity patterns and lagoon reclamation levels. Our results demonstrated that waterbird assemblages conserved at low reclamation lagoons have significant over-dispersion patterns in Standardized Effect Sizes of Mean Pairwise Phylogenetic Diversity (MPDses). The relationship between MPDses and reclamation level was weakened by season. For functional diversity, the relationship between FRic and low reclamation was strengthened in spring significantly. However, taxonomic diversity showed not significant differences between two reclamation level lagoons, Shannon-Wiener and Simpson index. We concluded that the MPDses and FRic of waterbird assemblages were more sensitive to environment changes than taxonomic diversity. We highlight that phylogenetic diversity as an ecological indicator to environmental changes should receive more attentions in future biodiversity and conservation studies.

Aquaculture is one of the fastest-growing economic activities in the world that results in a high amount of nitrogen-rich wastewater discharge into mangroves and affects the plant tissue’s decomposition. However, a comprehensive analysis of above- and belowground litter affected by the nitrogen (N) input is rare. This study investigated the responses of above- and belowground litter decomposition to the different levels of N input in decomposition rates, chemical components, and the release of chemical compounds. Exogenous N input had stimulating, retarding, or even no effect on plants’ litter decomposition and nutrient release in mangroves. The above- and belowground litter decompositions had different responses to anthropogenic N addition and varied among different mangrove species. The mechanism of the impacts of anthropogenic nitrogen input varies depending on species identity, litter composition, and additional N level. These results show that N enrichment in mangroves can be beneficial and detrimental to ecosystem function. For the native mangrove species, Kandelia obovata and Avicennia marina , the belowground tissues that had a direct correlation with carbon accumulation were significantly influenced by the additional N input. The worldwide problem of offshore aquaculture effluent discharge is a potential risk to the ecological function of mangroves in carbon storage.

Mangrove ecosystems are famed for their crucial ecological functionalities in moderating global carbon cycling process. To safeguard these ecosystems, the Chinese government implemented the Ecological Redline Policy (ERP) in 2017. This study evaluated the effectiveness of ERP in protecting mangroves and enhancing their carbon storage potential using multi-temporal Landsat-8 OLI images via InVEST Carbon Storage and Sequestration model, and field surveys conducted in Guangdong Province, which hosts the largest mangrove distribution in China. The results revealed a total increase of 2094 ha in mangrove area, with approximately 65.2% of mangroves increase currently included in the ERP zoning plan. Within ERP zones, the mangrove increment was 1365.55 ha, with a lower expansion rate of 20.7% while the Non-ERP zones exhibited an increment of 729.32 ha at a higher expansion rate of 38.3%. Furthermore, around 80.0% of carbon storage in mangroves was managed within ERP zones, with no significant difference in carbon density between ERP and Non-ERP zones, though both groups showed an overall increase in carbon density by 2021 compared to 2013. It is suggested that the ERP zone not only enhances carbon storage but also improves other ecological traits of ecosystem. However, the current ERP appeared to fall short of fully meeting strategic needs, emphasizing the necessity of optimized planning to minimize tradeoffs between environmental quality and development.

Mangrove ecosystems function simultaneously as carbon sinks and carbon sources. While their contribution to biomass accumulation and long-term carbon sequestration have been extensively studied, the mechanisms driving carbon emissions, particularly those mediated by tree species and microbial communities, remain poorly understood. In this study, we investigated Kandelia obovate (KO), Sonneratia apetala (SA), and an adjacent mudflat in the Hanjiang River Estuary, southern China, to evaluate seasonal changes in sediment physicochemistry, microbial community structure, and CO₂ fluxes, and to evaluate the influence of vegetation on carbon emissions. This research shows that mangrove colonization significantly altered sediment conditions, with K. obovata exhibiting higher salinity, water content, and total carbon concentration than S. apetala. Sediment CO₂ fluxes were consistently greater in mangrove habitats than in mudflats and displayed clear seasonal variation. In summer, sediment CO₂ fluxes in S. apetala and K. obovata were 4.3- and 2.5-fold higher than in winter, respectively. Concurrently, root respiration intensified in S. apetala during summer, whereas K. obovata root respiration remained stable across seasons. Microbial communities were dominated by Proteobacteria and Chloroflexi across sites, however, their network structures differed. S. apetala supported tighter microbial interactions, while K. obovata exhibited higher modularity and functional specialization. Additionally, partial least squares structural equation modeling revealed that sediment physicochemical properties strongly constrained microbial diversity and regulated CO₂ flux both directly and indirectly. These findings highlight the importance of sediment and root respiration in mangrove carbon cycling and demonstrate how species identity modulates CO₂ fluxes by shaping the interactions between sediment conditions and microbial communities.

Mangrove ecosystem plays a pivotal role in global climate change mitigation through blue carbon sequestration. Consequently, management initiatives have been widely implemented worldwide. However, the impact of hydrological condition and species selection on mangrove carbon sequestration lacks comprehensive understanding. In this study, a series of organic carbon-related parameters were measured in two sampling sites with different hydrological conditions and mangrove species (including native Aegiceras corniculatum, Kandelia obovata and exotic Laguncularia racemosa) in Guangdong, China. The results demonstrated that restoration of hydrological connection may contribute more to mangrove organic carbon stock accumulation than non-tidal condition in the impounded sites. This effect occurs through its influence on the dynamic equilibrium between allochthonous (vegetation-derived) and autochthonous (tidal input) organic carbon. Particularly, species-specific response to hydrological conditions determined the quantity and quality of the overall ecosystem organic carbon stock. The native A. corniculatum exhibited optimal growth and organic carbon accumulation in prolonged inundation and hypersaline conditions whereas K. obovata has adapted to environments with less tidal inundation/impoundment. Overall, native mangrove species showed superior performance in organic carbon stock stability, rendering their more suitability for long-term mangrove reforestation and afforestation projects. Overall, this study emphasized that hydrological restoration is of great significance in maximizing the organic carbon accumulation in mangrove ecosystems and should be given more priorities beyond mangrove afforestation.

Mangroves are important ecosystems that mediate the movement of organic matter and nutrients from land to the ocean via tidally driven porewater exchange. In the present study, we quantified porewater exchange rates in three 12-year-old Sonneratia apetala plantations distributed along the Pearl River Estuary in southern China by monitoring 222Rn in situ during the wet and dry seasons and by measuring the correlations between the porewater exchange rates and the mangrove plantation conditions. The 222Rn-derived porewater exchange rates were 385.1-1286.0 Bq m- 2 h- 1 in the wet season and 380.6-498.4 Bq m- 2 h- 1 in the dry season, which is higher than previous studies. Therefore, it is necessary to sample and monitor within the mangrove forests, or the porewater exchange should be underestimated because of the ignored richer crab burrows. Sediment pH, salinity, and surface water pH had significant relationships with the porewater exchange rate. These results revealed that porewater exchange had seasonal and spatial variation in mangroves and that pH and salinity were the major regulators of mangrove porewater physical exchange.

Mangrove ecosystems are famed for their crucial ecological functionalities in moderating the global carbon cycling process. In 2017, the Chinese government implemented the Ecological Redline Policy (ERP) nationwide to protect various ecological functions. However, there is a lack of multi-temporal, high-resolution spatial studies evaluating the effectiveness of ERP in mangrove protection, which hinders sustainable mangrove management. This study focuses on mangroves in Guangdong Province, China, which has the most extensive mangrove distribution in the country, during 2013, 2017, and 2021 using Landsat-8 OLI images (30 m). Field surveys provided data on floral components, forest structure, and biomass of mangrove sites. Subsequently, we assessed the current storage of blue carbon in mangroves using an InVEST Carbon Storage and Sequestration model. Additionally, we estimated the future capacity of blue carbon storage and sequestration under different scenarios of mangrove management. The results revealed a total increase of 2094 ha in mangrove area, with approximately 65.2% of mangroves currently included in the ERP zoning plan. Compared to the Non-Redline zone, the mangrove increment under ERP was higher (1365.55 ha) but with a lower growth rate (20.7%). Conversely, the Non-Redline zone exhibited an increment of 729.32 ha with a growth rate of 38.3%. Furthermore, around 80.0% of carbon storage in mangroves was managed within ERP zones, where the biomass and carbon per unit were at least twice as high as those in the Non-Redline zone. The study suggested that the prevailing ERP planning in China could substantially enhance the function of blue carbon sequestration in mangroves. However, it was evident that the current ERP does not fully meet strategic needs, and it also highlighted the need for optimized planning to minimize tradeoffs between environmental quality and development.

Mangrove afforestation is usually thought to be beneficial to mitigate the degradation and loss of mangroves. In Southern China, planting mangroves with the introduced Sonneratia apetala is also supportive to remove the invasive Spartina alterniflora. However, the influence of mangrove afforestation dominated by introduced species on macrobenthos, a vital joint of energy flow and nutrient cycling in mangroves, remains unclear. We explored the linkage between the functional traits of macrobenthos and the physicochemical properties of sediments in a coastal continuum including the mudflat (MF), exotic Spartinaalterniflora saltmarsh (SL), natural Avicennia marina forest (AM), and introduced S. apetala afforestation (SA) via a seasonal field survey. After removing the S. alterniflora invaded into mudflat via S. apetala afforestation, the sediment C/N ratio decreased compared to that of natural forest, while the concentrations of microphytobenthic chlorophyll-a increased. The macrobenthic inhabiting mode shifted from epifaunal to infaunal as well. The biomass and density of microbenthic community decreased along MF, SL, AM, and SA. SL had greater C/N ratio and smaller functional richness (FR) than MF. AM was characterized by similar functional diversities, and pH value and salinity of sediment to those of MF, and greater microphytobenthic chlorophyll-a was found in AM. Compared to AM, the introduced S. apetala substantially engineered the habitat due to its flourishing above-ground pneumatophore system which caused faster deposition process, subsequently changed the resource utilization strategies of macrobenthos considerably. Overall, the use of Sonneratia afforestation on Spartina removal could not replace the contribution of natural Avicennia forest with respect to the functional traits of macrobenthos. Careful consideration on ecosystem functionalities would be indispensable for conducting saltmarsh eradication and mangrove afforestation in the future.

Urbanization carries essential influences to ecosystem of soil bacteria in coastal cities. Comprehending the patterns and drivers of bacterial diversity are essential to understanding how soil ecosystems respond to environmental change. This study aimed to explore how soil bacterial community (SBC) response to distinct urbanization of coastal cities on composition, assembly process and potential function in Guangdong province, south China. 72 samples from 24 sample sites within 3 cities were included in the study. Soil chemical properties were analyzed, and the bacterial community were investigated by high-throughout sequencing. Proteobacteria and Acidobacteria were the main phyla. Assembly processes remained in stochastic processes and co-occurrence network of SBC kept stable, while urbanization altered SBC by influencing the dominant phyla. The indicators of communities in coastal city soils were the genera gamma_proteobacterium and beta_proteobacterium. Urbanized extent was the non-negligible factor which affected soil bacterial community, despite the total carbon was still the most vital. The impact of urbanization on bacterial communities might follow a non-linear pattern. Faprotax function prediction showed different urbanized coastal city soils share similar metabolic potential. Our study improved our understanding of the response of soil bacterial communities to urbanization in subtropical coastal cities and offered a useful strategy to monitor the ecology risk toward the soil under urbanization.

Coastal blue carbon (C) ecosystems are recognized as efficient natural C sinks and play key roles in mitigating global climate change. Microbially driven C, nitrogen (N) and sulphur (S) cycles are crucial for ecosystem functioning, but how microorganisms drive C sink formation and C sequestration in coastal sediments remains unclear.In this study, we conducted a comprehensive analysis of amino sugars, C, N and S cycling genes/pathways and their associated taxa in coastal sediments of native (Cyperus malaccensis and Kandelia obovata) and alien (Spartina alterniflora and Sonneratia apetala) vegetation.Compared to the alien-vegetated coastal sediment, the native-vegetated coastal sediment had significantly (p < 0.05) higher microbial necromass C and higher functional potentials of chemoautotrophic C fixation, C degradation, methane cycling, N2 fixation, S oxidation and sulphate reduction. Also, our analysis of coastal sediment microbiomes showed that S oxidation could be coupled with C fixation and/or nitrate/nitrite reduction. S oxidation, C degradation and C fixation were found to be key functional pathways for predicting sediment microbial necromass C. Additionally, the sulphur-oxidizing Burkholderiales metagenome-assembled genomes (MAGs) were a key functional group that dominated chemoautotrophic C fixation in coastal sediments.These results suggested that chemoautotrophic S oxidizers, in particular Burkholderiales with a novel lineage, might be the key microbial group that dominates microbial necromass C formation in coastal sediments through microbial anabolism (C fixation);the coupling of microbially driven C, N and S cycling processes; and the deposition of microbially derived C. This study provides novel insights into the importance of chemoautotrophic S oxidizers for microbial necromass formation and shed new light on the microbial mechanism of C sink formation in coastal ecosystems, which also has important implications for enhancing C sequestration in coastal wetlands.

发展红树林生态系统的高效碳汇能力是我国实现碳中和的有效方法之一,而红树林的固碳效率受多方面因素的影响.本研究探究了树种及滩地高程条件对红树林生态修复工程早期的固碳效果的影响,为基于碳汇功能的红树林生态修复工程选址、选种提供参考.选取广东省汕头市牛田洋红树林生态修复工程中3个种植块为研究对象,分别为高潮位区桐花树(HAc,high-intertidal Aegiceras corniculatum)、低潮位区无瓣海桑(LSa,low-intertidal Sonneratia apetala)和高潮位区无瓣海桑(HSa,high-intertidal S.apetala).在造林2,3 a后,分别测定及估算植物生长指标、生物量、碳储量以及表层土壤(0～60 cm)的理化性质指标及碳储量等参数,分析树种与滩地高程对红树林群落储碳功能的影响.结果表明,红树林定植发育过程带来了土壤的酸化、盐化及养分(TOC、TN、TP)积累,同时碳的外源供给比例随着造林时间增加而增加.造林3 a后,在相同潮位条件下,相比外来树种无瓣海桑[植物碳密度(16.00±3.76)t·hm-2;系统碳密度(48.54±2.38 t·hm-2)],乡土树种桐花树凭借较高的植株密度获得了更高的单位面积碳储量[植物碳密度(36.16±2.35)t·hm-2;系统碳密度(70.14±3.15)t·hm-2].而淹水胁迫促进了无瓣海桑幼苗生物量及碳储量的积累,长时间的潮汐冲刷则降低了土壤有机碳的数量和稳定性.因此,低潮位无瓣海桑群落的碳密度[植物碳密度(34.59±8.85)t·hm-2;系统碳密度(61.03±2.57)t·hm-2]显著高于高潮位,但土壤总有机碳含量及颗粒态碳含量较低.

Mangrove ecosystems are considered as hot spots of biogeochemical cycling, yet the diversity, function and coupling mechanism of microbially driven biogeochemical cycling along the sediment depth of mangrove wetlands remain elusive. Here we investigated the vertical profile of methane (CH4), nitrogen (N) and sulphur (S) cycling genes/pathways and their potential coupling mechanisms using metagenome sequencing approaches. Our results showed that the metabolic pathways involved in CH4, N and S cycling were mainly shaped by pH and acid volatile sulphide (AVS) along a sediment depth, and AVS was a critical electron donor impacting mangrove sediment S oxidation and denitrification. Gene families involved in S oxidation and denitrification significantly (P < 0.05) decreased along the sediment depth and could be coupled by S-driven denitrifiers, such as Burkholderiaceae and Sulfurifustis in the surface sediment (0–15 cm). Interestingly, all S-driven denitrifier metagenome-assembled genomes (MAGs) appeared to be incomplete denitrifiers with nitrate/nitrite/nitric oxide reductases (Nar/Nir/Nor) but without nitrous oxide reductase (Nos), suggesting such sulphide-utilizing groups might be an important contributor to N2O production in the surface mangrove sediment. Gene families involved in methanogenesis and S reduction significantly (P < 0.05) increased along the sediment depth. Based on both network and MAG analyses, sulphate-reducing bacteria (SRB) might develop syntrophic relationships with anaerobic CH4 oxidizers (ANMEs) by direct electron transfer or zero-valent sulphur, which would pull forward the co-existence of methanogens and SRB in the middle and deep layer sediments. In addition to offering a perspective on the vertical distribution of microbially driven CH4, N and S cycling genes/pathways, this study emphasizes the important role of S-driven denitrifiers on N2O emissions and various possible coupling mechanisms of ANMEs and SRB along the mangrove sediment depth. The exploration of potential coupling mechanisms provides novel insights into future synthetic microbial community construction and analysis. This study also has important implications for predicting ecosystem functions within the context of environmental and global change.

大型底栖动物的生物扰动作用是促进红树林生态系统物质转化和能量流动的重要过程.大型底栖动物可以改变沉积物理化性质,驱动微生物群落结构组成和功能,对红树林中的生物地球化学循环过程具有重要意义.本文聚焦红树林大型底栖动物生物扰动和其对微生物群落、微生物介导的生物地球化学循环影响的研究现状,分别综述了大型底栖动物和微生物的时空分布格局和影响因素,探讨了大型底栖动物扰动对红树林微生物生态功能调控的物理和化学关联,展望了大型底栖动物-微生物-红树林在群落组成、互作机制和生态功能上的研究前景.

Mangrove reforestation with introduced species has been an important strategy to restore mangrove ecosystem functioning. However, how such activities affect microbially driven methane (CH4), nitrogen (N), and sulfur (S) cycling of rhizosphere microbiomes remains unclear. To understand the effect of environmental selection and the evolutionary process on microbially driven biogeochemical cycles in native and introduced mangrove rhizospheres, we analyzed key genomic and functional profiles of rhizosphere microbiomes from native and introduced mangrove species by metagenome sequencing technologies. Compared with the native mangrove (Kandelia obovata, KO), the introduced mangrove (Sonneratia apetala, SA) rhizosphere microbiome had significantly (p < 0.05) higher average genome size (AGS) (5.8 vs. 5.5 Mb), average 16S ribosomal RNA gene copy number (3.5 vs. 3.1), relative abundances of mobile genetic elements, and functional diversity in terms of the Shannon index (7.88 vs. 7.84) but lower functional potentials involved in CH4 cycling (e.g., mcrABCDG and pmoABC), N-2 fixation (nifHDK), and inorganic S cycling (dsrAB, dsrC, dsrMKJOP, soxB, sqr, and fccAB). Similar results were also observed from the recovered Proteobacterial metagenome-assembled genomes with a higher AGS and distinct functions in the introduced mangrove rhizosphere. Additionally, salinity and ammonium were identified as the main environmental drivers of functional profiles of mangrove rhizosphere microbiomes through deterministic processes. This study advances our understanding of microbially mediated biogeochemical cycling of CH4, N, and S in the mangrove rhizosphere and provides novel insights into the influence of environmental selection and evolutionary processes on ecosystem functions, which has important implications for future mangrove reforestation.

Global recognition that mangroves support coastal ecosystem services has increased; however, studies on trophic dynamics in mangrove ecosystems remain limited. We seasonally analysed the δ13C and δ15N of 34 consumers and 5 diets to elucidate the food web dynamics in the Pearl River Estuary (PRE). Fish had a large niche space during the monsoon summer, reflecting increased trophic roles. In contrast, the small niche space of benthos over seasons reflected consistent trophic positions. Consumers mainly utilized plant-derived organic matters in the dry season and particulate organic matters in the wet season. The present study with literature reviews revealed characteristics of the PRE food web with the depleted δ13C and enriched δ15N, indicating a high contribution of mangrove-derived organic carbon and sewage input, particularly in the wet season. Overall, this study confirmed the seasonal and spatial trophic dynamics in mangrove forests surrounding megacities for future sustainable mangrove ecosystem management.

Early evidence has elucidated that the spread of antibiotic (ARGs) and metal resistance genes (MRGs) are mainly attributed to the selection pressure in human-influenced environments. However, whether and how biotic and abiotic factors mediate the distribution of ARGs and MRGs in mangrove sediments under natural sedimentation is largely unclear. Here, we profiled the abundance and diversity of ARGs and MRGs and their relationships with sedimental microbiomes in 0-100 cm mangrove sediments. Our results identified multidrug-resistance and multimetal-resistance as the most abundant ARG and MRG classes, and their abundances generally decreased with the sediment depth. Instead of abiotic factors such as nutrients and antibiotics, the bacterial diversity was significantly negatively correlated with the abundance and diversity of resistomes. Also, the majority of resistance classes (e.g., multidrug and arsenic) were carried by more diverse bacterial hosts in deep layers with low abundances of resistance genes. Together, our results indicated that bacterial diversity was the most important biotic factor driving the vertical profile of ARGs and MRGs in the mangrove sediment. Given that there is a foreseeable increasing human impact on natural environments, this study emphasizes the important role of biodiversity in driving the abundance and diversity of ARGs and MRGs.

Mangroves around the world settle along coasts and estuaries, where they usually encounter aquaculture effluent that causes eutrophication and regulates the nitrogen cycle in their ecosystems. Moreover, the physical–chemical features of sediment in mangrove habitats might be altered by coastal wind, waves, and currents more frequently under the condition of increasing extreme climatic events. These events affect the process of colonization/regeneration of mangroves. To study how exogenous nitrogen input and sediment texture affect root system establishment of mangrove propagules and the early growth of seedlings, in turn, we set up a mesocosm experiment to explore the morphological and physiological responses of the root system of two mangroves, i.e., Kandelia obovata and Sonneratia apetala. We found that the root morphological features of mangrove seedlings mostly showed significant differences across the sediment texture treatment; K. obovata seedlings were more intensively influenced than S. apetala seedlings. It could be ascribed that the roots of K. obovata seedlings were more sensitive to sediment texture than S. apetala seedlings. Conversely, the treatment of exogenous nitrogen input showed a slighter even non-significant influence on the root features of mangrove seedlings. These results suggest that the seedlings of S. apetala and K. obovata performed similarly. In estuaries and coasts featuring eutrophication and various sediment textures, the conservation and restoration of mangroves should consider these conditions to ensure the sustainable development of mangroves.