To predict the consequences of environmental change on the biodiversity of alpine wetlands, it is necessary to understand the relationship between soil properties and vegetation biodiversity. In this study, we investigated spatial patterns of aboveground vegetation biomass, cover, species diversity, and their relationships with soil properties in the alpine wetlands of the Gannan Tibetan Autonomous Prefecture of on the Qinghai-Tibetan Plateau, China. Furthermore, the relative contribution of soil properties to vegetation biomass, cover, and species diversity were compared using principal component analysis and multiple regression analysis. Generally, the relationship between plant biomass, coverage, diversity, and soil nutrients was linear or unimodal. Soil pH, bulk density and organic carbon were also significantly correlated to plant diversity. The soil attributes differed in their relative contribution to changes in plant productivity and diversity. pH had the highest contribution to vegetation biomass and species richness, while total nitrogen was the highest contributor to vegetation cover and nitrogen–phosphorus ratio (N:P) was the highest contributor to diversity. Both vegetation productivity and diversity were closely related to soil properties, and soil pH and the N:P ratio play particularly important roles in wetland vegetation biomass, cover, and diversity.

Background: Unvegetated tidal flats of mangrove ecosystems in estuarine and non-estuarine areas play a crucial role in the coastal blue carbon sinks and biogeochemical cycle. However, there is still a lack of comprehensive understanding of the differences in soil organic carbon (SOC) contents in mangrove tidal flats between estuarine and non-estuarine areas, as well as their influencing factors. Methods: In this study, soil samples were collected from estuarine and non-estuarine mangrove tidal flats in the Leizhou Peninsula. We compared the SOC and soil physicochemical properties between estuarine and non-estuarine mangrove tidal flats. The Random Forest algorithm was employed to identify the main influencing factors affecting SOC. The direct and indirect effects of the main influencing factors on SOC were studied using partial least squares structural equation modeling. Results: SOC, total nitrogen (TN), total phosphorus (TP), available potassium (AK), clay, silt, aluminum (Al), lithium (Li), boron (B), molybdenum (Mo), and cadmium (Cd) contents in the estuarine areas were significantly higher than those in the non-estuarine areas of the mangrove tidal flats. The soil particle size (clay, silt, and sand), soil nutrient (TN and TP), and soil metal elements (Al, Mo, and Cd) were the main influencing factors of the SOC contents in the estuarine and non-estuarine mangrove tidal flat areas. Soil particle size (clay, silt, and sand) indirectly positively influenced SOC contents by positively influencing soil nutrient (TN and TP). Conclusions: Our findings indicate that estuarine tidal flats have higher capacity of SOC sequestration compared with non-estuarine tidal flats. The main cause is that soil particle size has the potential to significantly increase SOC content by increasing soil nutrients, while metal elements have a direct influence on SOC content. The findings of the present study highlight an important mechanism that influences SOC contents in estuarine and non-estuarine mangrove tidal flats.

A belowground bud bank is a collection of asexual propagules produced by the underground storage organs of geophytes. Renewal through belowground bud banks is the main reproductive strategy of geophytes. The belowground bud bank density reflects the potential renewal capacity of geophyte communities. However, the effects of different perturbation regimes and habitats on the belowground bud bank density of geophytes are not comprehensively understood. Moreover, whether different types of belowground bud banks respond differently to perturbations is still unclear. For this meta-analysis, relevant papers on the effects of environmental perturbations on the belowground bud bank density of geophytes were systematically collected. The cumulative effect size of different perturbation regimes and habitats on belowground bud banks among different bud types was analyzed. Overall, the effect of environmental perturbations on belowground bud bank density was small, which may result from opposite or fluctuating responses of bud banks to different perturbations. Drought negatively affected bud bank density. Environmental perturbations decreased rhizome bud density but increased tiller bud density. In wetlands, perturbations decreased belowground bud bank density. However, no significant effect was found for other habitat types. In general, belowground bud banks of geophytes are highly resistant and resilient. Changes in belowground bud bank density depend on the type of perturbations, the habitats in which plants are distributed and the type of bud banks.

Mangrove forests are large pools of soil organic carbon (SOC) found across the world, and play a vital role in global carbon (C) cycling. In this study, to investigate the effects of spatial factors on SOC in mangrove forests, soil samples at different depth layers from upper estuary (UE), lower estuary (LE), and tidal inlet (TI) in the Qinglangang mangrove forest in Southern China were collected and the differences in SOC among the layers and geomorphological settings were compared. The mean SOC content showed a pattern of LE (4.63 ± 1.28%) > UE (2.94 ± 0.73%) > TI (1.44 ± 0.33%). SOC content and storage decreased with soil depth in TI, but increased in UE. The total SOC storages (0–80 cm) of sites TU, UE, and LE, were 104.41 ± 16.63, 207.14 ± 44.83, and 228.78 ± 19.37 Mg/ha, respectively. The results suggested that top- and subsoil organic C content and storage were largely dependent on their specific location, which underwent different river-sea interactions and human activities. The SOC of the soil profile varied at different sites, implying that the current C storage of mangrove ecosystems can be accurately estimated by quantifying the C of sediments at sites.

Mangrove ecosystems represent critical coastal blue carbon sinks, whose ecological stability is essential for sustaining carbon sequestration capacity and coastal ecological security. Hyblaea puera, a dominant defoliating pest in mangrove habitats, exhibits abrupt population outbreaks and extreme destructive potential, severely threatening the integrity of blue carbon ecosystems. While conventional broad-spectrum chemical insecticides deliver adequate control efficacy, they often exert detrimental effects on non-target organisms and adjacent coastal marine environments, conflicting with core mangrove conservation objectives. Azadirachtin, a botanical insecticide with high lepidopteran target highly selective, is a promising eco-friendly alternative; nevertheless, the dual stresses of periodic tidal flushing and intense ultraviolet radiation in intertidal mangrove habitats drive rapid photodegradation and leaching loss of azadirachtin, leading to poor field persistence and slow lethal action of the free formulation. These limitations render neat azadirachtin insufficient to meet the urgent demand for rapid emergency control of H. puera during population outbreaks. To address these technical bottlenecks, we developed an azadirachtin-loaded dendritic mesoporous silica nanoparticle delivery system to simultaneously improve the environmental stability and fast-acting insecticidal efficacy of azadirachtin against H. puera. Specifically, dendritic mesoporous silica nanoparticles (DMSNs) were synthesized via a one-pot method, then loaded with azadirachtin (ADT) and further surface-modified with polyether-modified heptamethyltrisiloxane (PM) to fabricate the ADT@DMSN/PM nano-delivery system. The physicochemical properties, intertidal habitat adaptability, insecticidal activity, and environmental safety of the fabricated system were systematically evaluated. Characterization results showed that the as-synthesized DMSNs had a uniform particle size of 200–300 nm, a specific surface area of 260.99 m²/g, and an ADT loading efficiency of 66.6%. ADT@DMSNs exhibited prominent alkaline-responsive sustained-release behavior, with a cumulative ADT release of 57.0% at pH 8.2 (mangrove seawater conditions) over 500 h. Laboratory bioassays revealed that the 24 h median lethal concentrations (LC₅₀) of ADT@DMSNs against third-, fourth-, and fifth-instar H. puera larvae were 84.36, 188.08, and 458.65 μg/mL, respectively, representing 2.38-, 2.63-, and 2.86-fold enhancements in insecticidal activity compared with free ADT. After modification with the PM adjuvant, the nanoformulation exhibited a significantly reduced contact angle on Avicennia marina leaves, over 3-fold higher foliar penetration efficiency, and markedly improved tidal wash-off resistance. Field cage bioassays demonstrate that the ADT@DMSN/PM nanoformulation yields a corrected mortality of approximately 95% against H. puera larvae at 1200 mg/L at 24 h. This nano-delivery system is precisely tailored to the unique environmental constraints of mangrove intertidal habitats, offering a novel eco-friendly technical approach to achieve rapid emergency control of H. puera outbreaks.

Aims Mangrove ecosystems possess a high capacity for carbon sequestration, with the sediment carbon pool accounting for the majority of total carbon storage. Humic carbon is the primary form of sediment organic carbon, its content typically accounting for more than half of organic carbon content in sediments. However, the distribution patterns and primary driving factors of humic carbon components in different types of mangroves remain poorly understood. Methods In this study, we focused on four typical mangrove types, i.e., Bruguiera gymnorrhiza forest, Kandelia obovata forest, Rhizophora stylosa forest, and Avicennia marina forest, at the Guangdong Zhanjiang Mangrove National Nature Reserve in South China. We quantitatively analyzed the distribution patterns of three humic carbon fractions, i.e., humic acid carbon, fulvic acid carbon, and humin carbon, in sediments of four different mangrove types and at different sediment depths. We also performed correlation analysis, random forest models, and hierarchical partitioning to identify their main environmental driving factors. Important findings Humic carbon contents in mangrove sediments varied significantly with forest type and soil depth, with the highest level generally found in R. stylosa forests and the lowest level in A. marina forests. Humic carbon contents decreased significantly with increasing sediment depth and stabilized below 40 cm. The humic carbon contents showed significant positive correlations with multiple environmental factors, but the dominant controlling factor varied with forest type. The availability of sediment nutrients, particularly available nitrogen content and the carbon-to-nitrogen ratio, was a key factor influencing humic carbon components, with available nitrogen content explaining 34.20% of the variation in humin carbon content. Sedimentary metal elements (such as chromium) content exerted a significant influence on fulvic acid carbon content and humin carbon content, explaining 12.04% and 16.83% of the variations, respectively. Collectively, our results demonstrate that the variation of spatial distribution of humic carbon in mangrove sediments is primarily determined by nutrient availability. The specific metal elements such as chromium exert significant regulatory effects on components like fulvic acid and humic substances. However, the influence of soil microorganisms is relatively minor.