Coastal Wetland Ecosystems Research Articles

Warming accelerates belowground litter turnover in salt marshes – insights from a Tea Bag Index study

Abstract. Salt marshes play an important role in the global carbon cycle due to the large amount of organic carbon stored in their soils. Soil organic carbon formation in these coastal wetland ecosystems is strongly controlled by the plant primary production and initial decomposition rates of plant belowground biomass and litter. This study used a field warming experiment to investigate the response of belowground litter breakdown to rising temperature (+1.5 and +3.0 ∘C) across whole-soil profiles (0–60 cm soil depth) and the entire intertidal flooding gradient ranging from the pioneer zone via the low marsh to high marsh. We used standardized plant materials, following the Tea Bag Index approach, to assess the initial decomposition rate (k) and the stabilization factor (S) of labile organic matter inputs to the soil system. While k describes the initial pace at which labile (= hydrolyzable) organic matter decomposes, S describes the part of the labile fraction that does not decompose during deployment in the soil system and stabilizes due to biochemical transformation. We show that warming strongly increased k consistently throughout the entire soil profile and across the entire flooding gradient, suggesting that warming effects on the initial decomposition rate of labile plant materials are independent of the soil aeration (i.e., redox) status. By contrast, negative effects on litter stabilization were less consistent. Specifically, warming effects on S were restricted to the aerated topsoil in the frequently flooded pioneer zone, while the soil depth to which stabilization responded increased across the marsh elevation gradient via the low to high marsh. These findings suggest that reducing soil conditions can suppress the response of belowground litter stabilization to rising temperature. In conclusion, our study demonstrates marked differences in the response of initial decomposition rate vs. stabilization of labile plant litter to rising temperature in salt marshes. We argue that these differences are strongly mediated by the soil redox status along flooding and soil-depth gradients.

Coastal Wetland Restoration Strategies Based on Ecosystem Service Changes: A Case Study of the South Bank of Hangzhou Bay

A unique variety of wetlands known as coastal wetlands that connect terrestrial and marine ecosystems is crucial to reducing and adapting to climate change as well as the advancement of human culture. However, the coastal wetland ecosystem is currently in danger as a result of the increasing intensity of human activity, and wetland restoration and reconstruction have garnered a lot of interest. The differentiated ecological restoration strategies based on ecosystem service change analysis can provide a reference for the effective management and sustainability of coastal wetland ecosystems. The InVEST model and ArcGIS were used to analyze the spatiotemporal changes in ecosystem services before and after the implementation of coastal wetland restoration policies based on remote sensing image data, meteorological and soil data, etc. The ecological restoration pattern of coastal wetlands was divided, and the corresponding ecological restoration strategies were proposed in this study. The following are the results: (1) there are still many wetlands that have been converted to non-wetlands following the implementation of the wetland restoration policy, and the ecosystem services as a whole exhibit a rising and then falling trend, with a rise from 2005 to 2015, a fall in 2015 due to the creation of Hangzhou Bay New District, and a slight improvement to 2020. Among them, the water yield increased continuously, the carbon storage fluctuated, and the habitat quality did not improve significantly. (2) The hot spots of ecosystem services were concentrated in the south and southeast of the study area, with no obvious cold spots. (3) By comprehensively analyzing the changes and spatial patterns of ecosystem services, the coastal wetlands on the south bank of Hangzhou Bay were divided into an ecological conservation zone, a green development zone, and an ecological restoration zone at the township level, and corresponding optimization strategies were proposed. The results can provide a reference for the fine-grained and differentiated management of regional ecosystem services.

Effect of Spartina alterniflora Invasion on Soil C:N:P Stoichiometry in Coastal Wetland of Hangzhou Bay

The invasion of Spartina alterniflora poses a great threat to coastal wetland ecosystems. In this study, the stoichiometric characteristics of soil carbon, nitrogen, and phosphorus under a Spartina alterniflora invasion were explored using ANOVA in a coastal wetland in Hangzhou Bay, and the driving coupling relationship between soil environmental factors and soil C:N:P stoichiometric characteristics of the coastal wetland were further explored based on the redundancy analysis (RDA), boosted regression tree (BRT), and partial least squares-structural equation (PLS-SEM) model. The results showed that:① after the invasion of Spartina alterniflora, soil N:P and total nitrogen (TN) in the wetland increased significantly, and with the increase in invasion time, TN and N:P decreased significantly, whereas soil organic carbon (SOC), C:N, and C:P increased significantly. ② The RDA model revealed that the main factors affecting the stoichiometric characteristics of topsoil C:N:P were SOC>electrical conductivity (EC)>TN in winter and SOC>bulk density (BD)>TN in summer. ③ The BRT model showed that under the invasion of Spartina alterniflora, TN was the key factor affecting soil C:N and N:P, and SOC was the key factor affecting C:P. ④ The PLS-SEM model showed that clay and water content directly affected SOC, thus affecting C:N and C:P; the clay and EC directly affected total phosphorus (TP), thus affecting N:P and C:P; and the EC directly affected TN, thus affecting C:N and N:P. In conclusion, the invasion of Spartina alterniflora had a significant impact on soil C:N:P stoichiometric characteristics in the study area. Soil physical properties and nutrient content directly or indirectly affected soil C:N:P stoichiometric characteristics to varying degrees.

Net ecosystem productivity of Panjin Phragmites australis wetland during 1971 to 2020 and its impact factors.

Coastal estuarine wetland ecosystem has strong ability for carbon (C) storage and sequestration. Accurate assessment of C sequestration and its environmental impact factors is the basis of scientific protection and mana-gement of coastal estuarine wetlands. Taking the Panjin reed (Phragmites australis) wetland as the object, we used terrestrial ecosystem model, together with Mann-Kendall mutation test, statistical analysis methods, and scenario simulation experiment, to analyze the temporal characteristics, stability, changing trend of net ecosystem production (NEP) of wetlands and the contribution rate of environmental impact factors to NEP during 1971 to 2020. The results showed that the annual average NEP of Panjin reed wetland was 415.51 g C·m-2·a-1 during 1971 to 2020, with a steady increase rate of 1.7 g C·m-2·a-1, which would still have a continuous increasing trend in the future. The annual average NEP in spring, summer, autumn, and winter was 33.95, 418.05, -18.71, and -17.78 g C·m-2·a-1, with an increase rate of 0.35, 1.26, 0.14 and -0.06 g C·m-2·a-1, respectively. In the future, NEP would show an increasing trend in both spring and summer, but a declining trend in both autumn and winter. The contribution rates of environmental impact factors to NEP of Panjin reed wetland depended on temporal scale. At the interannual scale, the contribution rate of precipitation was the highest (37.1%), followed by CO2 (28.4%), air temperature (25.1%) and photosynthetically active radiation (9.4%). Precipitation mainly affected NEP in both spring and autumn with the contribution rates of 49.5% and 38.8%, while CO2 concentration (36.9%) and air temperature (-86.7%) were dominant in summer and winter, respectively.

Forecasting land-cover change effects on waterbirds in Xiamen Bay, China: Determining prospective species winners and losers

Waterbirds are vital to coastal wetland ecosystem, and play significant roles in global biodiversity maintenance, cultural and educational services, etc. Waterbirds are particularly vulnerable to environmental change, particularly land-cover change, which has severely degraded their ecological niches. Accordingly, this study developed a waterbird-habitat preference index to quantify waterbird dependence on Xiamen Bay's habitats and a subsidiary waterbird-specific habitat suitability index to predict potential effects of future land-cover change on waterbirds. Results showed that the waterbird-habitat preference index ranged from −9.8 to 18.71, indicating that habitat selection varied greatly among different waterbird species, where tidal flats were the most popular waterbird habitat. Additionally, most waterbird species showed a preference for more than one habitat, which could be indicative of their diverse ecological demands. Effects on waterbirds varied greatly among the three different land-cover scenarios, where positive benefits were predicted under the ecological protection scenario (EPS), while the greatest negative effects were observed under the development and utilization scenario (DUS). Effects also varied among different waterbirds species. Those under the current trend scenario (CTS) (e.g., Tringa brevipes and Calidris ruficollis) could be at risk for species abundance loss (i.e., losers) while others (i.e., Egretta garzetta and Saundersilarus saundersi) could benefit from increased abundance (i.e., winners). Generally, migratory and traveling birds were much more vulnerable than resident birds. Spatially, conservation priority should be given to the Dadeng Waters and those waters adjacent to it (i.e., Tongan Bay and Anhai Bay) because of the highest waterbird loss risk in these areas under a conflict between an urgent need to protect waterbird biodiversity and intense present and future land-cover development. The intent of this study is to provide a useful tool to explore land-cover effects on waterbirds in similar coastal regions, which can provide important information on protection and restoration strategies.

Spatiotemporal Heterogeneity of Coastal Wetland Ecosystem Services in the Yellow River Delta and Their Response to Multiple Drivers

Understanding on the spatiotemporal interactions between ecosystem services (ESs) and social–ecological drivers is crucial for the design of sustainable development strategies for coastal wetlands. In this paper, we took the Yellow River Delta (YRD) as a case study, based on multiple evaluation methods to study the spatiotemporal dynamics of ESs in the YRD from 1980 to 2020. With the help of principal component analysis (PCA) for identification of multiple drivers, we researched the spatiotemporal differentiation and influence mechanism of drivers on ESs, using the coupling coordination degree (CCD) model and geographically and temporally weighted regression (GTWR) model, and subsequently provided the development strategy for each district in Dongying City. The results showed that (1) the patterns of ESs were spatially heterogeneous, with a fluctuating upward trend from 1980 to 2020, which was mainly affected by regulating service. (2) Our spatiotemporal analysis of ES interactions identified that cultural service was mainly disorder with other ESs. Nevertheless, in wetlands, various ESs can basically develop in a coordinated manner. (3) We integrated multiple drivers into five principal components by PCA, to which the response of ESs had spatial heterogeneity. (4) Consequently, we integrated spatiotemporal knowledge on ES interactions and their drivers into spatial planning.

Invasion patterns of Spartina alterniflora: Response of clones and seedlings to flooding and salinity—A case study in the Yellow River Delta, China

The invasion of Spartina alterniflora has caused severe damage to the coastal wetland ecosystem of the Yellow River Delta, China. Flooding and salinity are key factors influencing the growth and reproduction of S. alterniflora. However, the differences in response of S. alterniflora seedlings and clonal ramets to these factors remain unclear, and it is not known how these differences affect invasion patterns. In this paper, clonal ramets and seedlings were studied separately. Through literature data integration analysis, field investigation, greenhouse experiments, and situational simulation, we demonstrated significant differences in the responses of clonal ramets and seedlings to flooding and salinity changes. Clonal ramets have no theoretical inundation duration threshold with a salinity threshold of 57 ppt (part per thousand); Seedlings have an inundation duration threshold of about 11 h/day and a salinity threshold of 43 ppt. The sensitivity of belowground indicators of two propagules-types to flooding and salinity changes was stronger than that of aboveground indicators, and it is significant for clones (P < 0.05). Clonal ramets have a larger potentially invadable area than seedlings in the Yellow River Delta. However, the actual invasion area of S. alterniflora is often limited by the responses of seedlings to flooding and salinity. In a future sea-level rise scenario, the difference in responses to flooding and salinity will cause S. alterniflora to further compress native species habitats. Our research findings can improve the efficiency and accuracy of S. alterniflora control. Management of hydrological connectivity and strict restrictions on nitrogen input to wetlands, for example, are potential new initiatives to control S. alterniflora invasion.

Habitat suitability and potential biological corridors for waterbirds in Yancheng coastal wetland of China

Yancheng coastal wetland, as an important part of the East Asian–Australasian Flyway, provided habitat for more than 200 migratory waterbirds by rest and over-winter. After it was listed as a “World Heritage List” in 2019, the protection of waterfowl habitat in Yancheng coastal wetland has attracted extensive attention from the international community. As an indicator species of Yancheng coastal wetland ecosystem health, waterbirds have practical significance for the protection of Yancheng coastal wetlands. Due to the long-term impact of human activities, the waterbird habitats are facing the threat of habitat fragmentation and lose, posing a serious challenge to its survival and diversity. Based on the survey data obtained Gruiformes, Charadriiformes, and Anseriformes waterbirds during the whole years from 2017 to 2021, this paper used the Maxent software for modeling species niches and distributions, a comprehensive evaluation method based on fuzzy mathematics, and Linkage Mapper model to assess the habitat suitability distribution of waterbirds, identify protection gaps and potential biological corridors for waterbirds in Yancheng coastal wetland. The results showed that habitat suitability and anthropogenic disturbance were the decisive factors affecting habitat selection of waterbirds. The suitable habitats for Gruiformes, Charadriiformes, and Anseriformes waterbirds were 23868, 22670, and 24870 ha, respectively. The suitable habitat area of waterbirds was 121,930 ha, concentrated on the study area's central and southern coast. Sheyang estuary was identified as a vital conservation gap in the study area. Meanwhile, biological corridors of a total of 33 waterbirds were identified in the study area. The longest biological corridor was 18.78 km, and the shortest was 0.09 km. Our research can provide scientific support for Yancheng coastal wetland protection and the improvement of waterbird diversity, together with the achievements of an ecological and sustainable situation between environmental conservation and economic development.

Analysis of the expression and function of the CBL-CIPK network and MAPK cascade genes in Kandelia obovata seedlings under cold stress

Mangroves are an important component of coastal wetland ecosystems, and low temperature is the main factor that limits their extension to higher latitudes. Kandelia obovata as one of the most cold-tolerant species in mangrove ecosystems can provide basis for the northward migration of mangrove ecosystems. We took K. obovata seedlings from Zhoushan (Zhoushan, Zhejiang, China) as the research object in this study. Transcriptome sequencing based on the Illumina HiSeqTM 2500 platform was performed to compare the transcriptome changes of roots, stems, and leaves before and after freezing and to reveal the molecular mechanisms of frost resistance. A total of 1560, 370, and 416 genes were differentially expressed in the roots, stems, and leaves before and after cold snaps, respectively. Among these differentially expressed genes, 13 positive and negative regulators were attributed to the CBL-CIPK signaling network and MAPK cascade, which might be related to the frost resistance mechanism of K. obovata Transcription factors such as AP2/EREBP and bHLH were involved in regulating the synthesis pathways of ethylene, cytokinin, growth hormone, and flavonoids. Results provide new insights into the frost resistance mechanism of K. obovata seedlings.

Effects of nitrogen and phosphorus supply levels and ratios on soil microbial diversity-ecosystem multifunctionality relationships in a coastal nontidal wetland

Human activities have changed the levels and ratios of nitrogen (N) and phosphorus (P) in wetland ecosystems. However, the effects of N and P levels and ratios on wetland soil microbial community and ecosystem multifunctionality remain unclear, especially on the relationships between soil microbial diversity and ecosystem multifunctionality. In this study, the effects of a 7-year experimental nutrient addition on the soil microbial community and ecosystem multifunctionality (12 function variables related to carbon, N, and P cycling) were assessed by combining three N and P supply levels with three N:P supply ratios in a coastal nontidal wetland ecosystem. According to the obtained results, the N and P supply levels significantly affected soil bacterial community composition, as well as ecosystem multifunctionality, while no significant effects of N:P supply ratios were observed. Although N and P supply levels did not significantly affect bacterial and fungal diversity, they both changed the complexity of bacterial and fungal networks. Soil ecosystem multifunctionality was significantly and positively correlated with bacterial diversity rather than fungal diversity. Moreover, the correlation coefficient between bacterial diversity and ecosystem multifunctionality showed an increasing-decreasing trend with increasing N and P supply levels and an increasing trend with increasing N:P supply ratios. However, the correlation coefficient between bacterial diversity and ecosystem multifunctionality was not significantly correlated with bacterial network complexity. The current study provides new insights into the impacts of N and P levels and ratios on soil microbial community and ecosystem multifunctionality in a coastal nontidal wetland. In particular, the present study highlighted that changes in N and P supply levels and ratios lead to changes in the relationship between soil bacterial diversity and ecosystem multifunctionality, which should be considered in related studies to accurately predict the responses of ecosystem multifunctionality to N and P inputs in coastal nontidal wetlands.

Identifying priorities for reform to integrate coastal wetland ecosystem services into law and policy

The ecosystem services concept has been slow to integrate into written law and policy in Australia. We sought to examine whether the concept has permeated deeper into practice, focusing on the coastal wetland protection, management and restoration context. We conducted a Delphi study involving 16 key informants. Over two rounds of interviews we found confirmation that the ecosystem services concept is not a central part of practice, and a strong consensus support for integrating and mainstreaming ecosystem services into law and policy through law reform. Our informants also provided additional new insights on how reform should proceed: (1) integration may occur through consolidated or interconnected law and policy instruments, (2) decision-maker discretion should be retained but subject to constraints, especially regarding (3) trade-offs between different ecosystem services and ecosystem services and other land uses. Our informants also called for (4) more effective and targeted policy to facilitate restoration projects, (5) incentivised protection and restoration across land tenure types, especially on privately-owned land and (6) caution in dealing with trade-offs and financial valuations of ecosystem services. The insights provided through this Delphi study will be instructive for law and policy reform in Australia and other jurisdictions grappling with fragmented management, protection and restoration of coastal wetlands.

Effects of Escherichia pollution and salinity on nutrient levels in submerged vegetated wetlands: Insights into benthic community stability and metabolisms.

Inner coastal wetland ecosystems are generally eutrophic and are often exposed to both salinity stress and Escherichia coli pollution. However, the effects of these stressors on nutrient-cycling and microbial communities are under-researched. Here, we established a vegetated wetland ecosystem in a saline environment to understand the effects of E. coli pollution on nutrient removal and benthic microorganisms. The results show that E. coli significantly inhibited nutrient removal, especially total nitrogen (TN) and ammonium (78.89-84.98 and 3.45-44.65% were removed from the non-E. coli-treated and the E. coli-treated water, respectively). Compared with non-vegetated systems, archaeal community variations at both compositional and phylogenetic levels were weakened in vegetated systems (p < 0.05). Among all the environmental factors, the ratios of PO43--P to total phosphorus and NO3--N to TN contributed the most to archaeal and bacterial community structural variations, respectively. E. coli pollution affected archaeal community succession more than bacteria (p < 0.05). E. coli also weakened the trophic transferring efficiencies between Cyanobacteria and Myxobacteria (p < 0.05). Metabolically, E. coli inhibited bacterial genetic metabolic pathways but made human infection more likely (p < 0.05). Our findings provide new insights into aquatic ecological conservation and environmental management.

Modeling strategies and data needs for representing coastal wetland vegetation in land surface models.

Vegetated coastal ecosystems sequester carbon rapidly relative to terrestrial ecosystems. Coastal wetlands are poorly represented in land surface models, but work is underway to improve process-based, predictive modeling of these ecosystems. Here, we identify guiding questions, potential simulations, and data needs to make progress in improving representation of vegetation in terrestrial-aquatic interfaces, with a focus on coastal and estuarine ecosystems. We synthesize relevant plant traits and environmental controls on vegetation that influence carbon cycling in coastal ecosystems. We propose that models include separate plant functional types (PFTs) for mangroves, graminoid salt marshes, and succulent salt marshes to adequately represent the variation in aboveground and belowground productivity between common coastal wetland vegetation types. We also discuss the drivers and carbon storage consequences of shifts in dominant PFTs. We suggest several potential approaches to represent the diversity in vegetation tolerance and adaptations to fluctuations in salinity and water level, which drive key gradients in coastal wetland ecosystems. Finally, we discuss data needs for parameterizing and evaluating model implementations of coastal wetland vegetation types and function.

Spatial–Temporal Evolution Monitoring and Ecological Risk Assessment of Coastal Wetlands on Hainan Island, China

Coastal wetlands are located at the intersection of land and sea and provide extremely important ecological services. The coastal wetlands of estuarine harbors are representative parts of the coastal wetlands. Changes that occur in estuarine harbor wetlands are microcosms of the changes occurring in the coastal wetlands more generally. The coastal wetlands of Hainan Island, China, are coastal wetlands typical of tropical islands and are extremely sensitive to climate change. In the context of global sea level rise, studying the characteristics of spatial and temporal distribution of coastal wetlands on Hainan Island, as well as changes in their vulnerability, could provide scientific and technological support to address the adverse effects of climate change. Using nine typical estuarine harbor wetlands as target areas, this study systematically studies the spatial–temporal evolution of coastal wetlands on Hainan Island from 1990 to 2020. The results suggest the following: (1) The total area of coastal wetlands has remained relatively stable, but the area of artificial wetlands, especially aquaculture ponds, has increased significantly. There is a clear spatial variability in the changes in mangrove wetlands, with a clear increase in the area of areas with a high degree of protection, such as Dongzhai Harbor (DZG). The area of the areas with a high intensity of human activity has been significantly reduced, such as Bamen Bay (BMG). (2) The overall ecological risk of coastal wetlands is low, with the average wetland risk index (WRI) of all harbors being below 0.15. The higher the degree of protection, the lower the ecological risk of the area, such as DZG. Human activities are the main factor causing increased ecological risk in wetlands. (3) Climate-change-induced sea level rise and the intensification of human activities are the main determinants of future trends in the spatial distribution of coastal wetlands and wetland ecosystem stability. The results of this study provide guidance on the conservation and restoration of coastal wetlands.

Marsh birds as ecological performance indicators for Lake Ontario outflow regulation

Water-level regulation can have significant impacts on coastal wetland ecosystems. In this study we sought to update marsh-bird-based ecological performance indicators (PIs) that support adaptive management of long-term outflow regulation for Lake Ontario. Previous PIs established in the mid-2000 s were based on single species and monitoring them required data not currently being collected at broad scales. We therefore focused on developing and validating community-level PIs using data from an ongoing, long-term, basin-wide monitoring program, the Coastal Wetland Monitoring Program (CWMP). After identifying species with documented responses to variation in water levels in the literature, we considered a suite of potential PIs by first examining correlations with both annual mean water levels and measures of interannual water-level fluctuations. We then used a mixed-modelling framework to determine which highly correlated PIs exhibited statistically significant relationships with water-level variables. Having established significant effects of water levels on the candidate PIs, we performed a power-sensitivity analysis to determine the degree of change in each PI that can be detected based on current CWMP sampling. From these analyses, we propose six potential marsh-bird based PIs: sum total abundance of sensitive marsh-obligate species, richness of sensitive marsh-obligate species, and abundance of each of red-winged blackbird (Agelaius phoeniceus), marsh wren (Cistothorus palustris), common gallinule (Gallinula galeata), and least bittern (Ixobrychus exilis). Of these, the community-based PIs of sum total abundance and richness of sensitive species appear most suitable for assessing the marsh-bird community response to outflow regulation on Lake Ontario.

Rapid plant trait evolution can alter coastal wetland resilience to sea level rise

Rapid evolution remains a largely unrecognized factor in models that forecast the fate of ecosystems under scenarios of global change. In this work, we quantified the roles of heritable variation in plant traits and of trait evolution in explaining variability in forecasts of the state of coastal wetland ecosystems. A common garden study of genotypes of the dominant sedge Schoenoplectus americanus, "resurrected" from time-stratified seed banks, revealed that heritable variation and evolution explained key ecosystem attributes such as the allocation and distribution of belowground biomass. Incorporating heritable trait variation and evolution into an ecosystem model altered predictions of carbon accumulation and soil surface accretion (a determinant of marsh resilience to sea level rise), demonstrating the importance of accounting for evolutionary processes when forecasting ecosystem dynamics.

Influence of Vegetation Dynamics on Soil Organic Carbon and Its Fractions in a Coastal Wetland

Coastal wetland ecosystems are highly efficient in sequestering carbon (C) to mitigate climate change. However, it is still unclear how vegetation dynamics affect soil organic carbon (SOC) and its fractions (labile and recalcitrant C (LC and RC)) in coastal wetlands. Here, we quantified the effects of saltmarsh vegetation dynamics on the SOC and its fractions using the invasiveSpartina alternifloraand co-occurring nativePhragmites australiscommunities as a model. SOC contents in these 2 communities showed similar spatial patterns with an inverted U-shaped curve from tidal mudflats to vegetated marshes. Our results suggested that plant ecophysiological traits play a primary role in regulating the spatial distribution of SOC. In addition, the lower ratio of leaf to shoot inP. australiscommunity facilitates the accumulation of RC, while the lower soil pH inS. alternifloramay accelerate the decomposition of RC. The findings indicated thatS. alternifloracould accumulate more C in the soil owing to its greater plant biomass and photosynthesis rate. However, the reduced soil pH byS. alterniflorainvasion might restrain SOC accumulation. Our findings shed light on the impacts of long-term species invasion on SOC and its fractions in coastal wetlands under global changes.

Genomic analyses provide insights into the evolution and salinity adaptation of halophyte Tamarix chinensis.

The woody halophyte Tamarix chinensis is a pioneer tree species in the coastal wetland ecosystem of northern China, exhibiting high resistance to salt stress. However, the genetic information underlying salt tolerance in T. chinensis remains to be seen. Here we present a genomic investigation of T. chinensis to elucidate the underlying mechanism of its high resistance to salinity. Using a combination of PacBio and high-throughput chromosome conformation capture data, a chromosome-level T. chinensis genome was assembled with a size of 1.32 Gb and scaffold N50 of 110.03 Mb. Genome evolution analyses revealed that T. chinensis significantly expanded families of HAT and LIMYB genes. Whole-genome and tandem duplications contributed to the expansion of genes associated with the salinity adaptation of T. chinensis. Transcriptome analyses were performed on root and shoot tissues during salt stress and recovery, and several hub genes responding to salt stress were identified. WRKY33/40, MPK3/4, and XBAT31 were critical in responding to salt stress during early exposure, while WRKY40, ZAT10, AHK4, IRX9, and CESA4/8 were involved in responding to salt stress during late stress and recovery. In addition, PER7/27/57/73 encoding class III peroxidase and MCM3/4/5/7 encoding DNA replication licensing factor maintained up/downregulation during salt stress and recovery stages. The results presented here reveal the genetic mechanisms underlying salt adaptation in T. chinensis, thus providing important genomic resources for evolutionary studies on tamarisk and plant salt tolerance genetic improvement.

Evaluation of coastal wetland ecosystem services based on modified choice experimental model: A case study of mangrove wetland in Beibu Gulf, Guangxi

The evaluation of the service value of coastal wetland ecosystem is of great significance for the scientific development and effective utilization of coastal wetland resources. It has been proved that the addition of attribute cut-offs in the choice experiment (CE) evaluation framework improves the validity of evaluation results. However, whether this improvement is due to the improvement of the questionnaire or the improvement of the utility equation cannot be distinguished with this framework. In this study, the modified selection model with cut-off is used to assess the two key elements of the modified selection model that differ from the traditional model. These are the CE questionnaire that leads to cut-off and the CE utility equation that incorporates cut-off. Each element pair is analyzed separately. Both are utilized to evaluate the impact of the validity of the results, and quantitatively evaluate the service value of the mangrove wetland ecosystem in the Beibu Gulf region, Guangxi, China. The results showed that: In 2021, the total value of mangrove wetland ecosystem services in the Beibu Gulf region was 1.181 billion yuan. In the modified CE model, both the improvement of the questionnaire and the improvement of the utility equation contribute to the improvement of the validity of the evaluation results; their contribution degree is equal. Regarding the choice model, based on the correction, the public's willingness to pay per capita values for strengthening the protection of mangroves are (in order): the improvement of biodiversity, mangrove forest coverage, water quality, and the appreciation of the landscape. Related values are 53.89 yuan, 47.00 yuan, 35.46 yuan, and 17.29 yuan, respectively. The results provide a scientific basis for the formulation of ecological management policies of coastal wetlands by the government.

Prediction of the landscape pattern of the Yancheng Coastal Wetland, China, based on XGBoost and the MCE-CA-Markov model

Coastal wetland is a crucial part of the blue carbon ecosystem, having unique structural characteristics and serving both land and water functions. These areas also offer strong carbon sequestration and storage capacity. However, human activities and climate change have led to an ongoing decline in wetland areas. As an important wetland reserve in China, the coastal wetlands of Yancheng, Jiangsu Province, bring together a great number of water resources, land resources, biological resources, landscape resources, mineral resources, energy resources, and many other resources. However, in recent years, the coastal wetlands of Yancheng have also faced a continuous reduction in area. In this study, an integrated model of the Extreme Gradient Boosting (XGBoost) algorithm and multi-criteria evaluation-cellular automata-Markov (MCE-CA-Markov) model was designed to determine the importance of the driving factors of landscape pattern change and predict the landscape pattern of coastal wetlands in 2025, based on the analysis of landscape pattern changes in 2005, 2010, 2015, and 2020 in Yancheng coastal wetlands, Jiangsu Province. The results showed that the landscape configuration of coastal wetlands in Yancheng changed significantly during 2005–2020. The total natural wetland landscape area declined steadily over that 15-year span, showing a total decrease of 2.971×104 ha; on the contrary, the artificial wetlands increased. The analysis of the driving factors of wetland damage showed that gross domestic product (GDP), distance to roads, and average precipitation were the key factors. Based on this model, the natural wetland landscape of Yancheng’s coastal wetlands is predicted to decline sharply in 2025, and the wetland salt marsh vegetation will be extensively converted to aquaculture and agricultural land. Constructed land is predicted to increase significantly, and the trend of urban expansion is obvious. The study concludes with practical suggestions for the sustainable development and ecological conservation of the Yancheng coastal wetland ecosystem based on the predicted scenario.