Salt Marsh Wetlands Research Articles

Tidal effects on ecosystem CO2 exchange in a Phragmites salt marsh of an intertidal shoal

Understanding the mechanisms and controlling factors of ecosystem CO2 exchange in tidal wetlands is of great benefit for research concerning the global carbon cycle and climate change. In spite of this, the multiple controls of ecosystem-atmosphere CO2 exchange in coastal wetlands subject to subdaily tidal flooding have yet to be adequately addressed. In this study, we investigated the tidal influence on ecosystem CO2 exchange in a Phragmites salt marsh of an intertidal shoal in the Changjiang estuary, based on eddy covariance (EC) measurements. The results revealed that the study area acted as a strong sink for atmospheric CO2 (net ecosystem exchange, NEE = -901 g C m−2) in 2018. Photosynthetically active radiation (PAR), air temperature (Ta), and vapor pressure deficit (VPD) were major drivers of NEE on both diel and multi-day scales. The tides, along with the bio-meteorological variables, strongly affect ecosystem photosynthesis (gross primary production, GPP) and ecosystem respiration (Reco) in the tidal wetland, especially on the multi-day scale. Regardless of which flux partitioning method was utilized, tidal inundation generally imposed inhibitory effects on GPP, which were directly attributed to tidal water level (TWL) and salinity. The daytime data-based estimates of Reco was also suppressed on average under the tidal inundation condition when Ta was higher relative to the non-inundation condition, reflecting the influence of TWL on Reco and the reduced sensitivity of Reco to Ta. We observed that NEE responded positively or negatively to tidal flooding, depending on the magnitude of tidal suppression on GPP and Reco. When Ta was roughly between 28 and 32°C and PAR was > 1200 μmol m−2 s−1, GPP was suppressed by tides more than Reco during the early and rapid vegetative stage, while during the peak vegetative stage, the opposite was true. This study not only shows the unique impact of tidal salt marsh wetlands on carbon uptake, but it also represents an example of a coastal wetland in which tidal inundation promotes the net uptake of CO2.

Hydrochemical Characteristics Jointly Determine the Transport and Cycling of Soil Carbon, Nitrogen, and Phosphorus in an Arid Chinese Wetland

AbstractSalt accumulation gradually changes the cycling of carbon (C), nitrogen (N), and phosphorus (P) and may even transform sinks into sources in arid wetlands. However, it's not clear how hydrochemical characteristics affect the wetland's source or sink function or how they affect C, N, and P cycling in arid regions. To clarify these relationships, we conducted field measurement in arid northern China. We simulated the variations of hydrochemical characteristics and the storage and stoichiometry of C, N, and P using the process‐based DeNitrification‐DeComposition (DNDC) and Hydrus‐1D models. The meteorological and hydrological processes had obvious characteristics of seasonal and interannual changes. The measured evapotranspiration averaged 660.23 and 587.94 mm year−1 in the saltmarsh and riparian wetlands, respectively. The soil showed a clear trend with higher SO42−, Na+, Ca2+, and Cl− fractions in comparison with lower Mg2+, K+, and HCO3− fractions, with the major ion and nutrient concentrations gradually decreasing with increasing depth in the soil. The major ion types had characteristics of Na+‐Ca2+‐SO42−‐Cl− in the saltmarsh wetland and riparian wetland. The storage of total C, N, and P were 372.72 ± 66.52 t C/hm2, 10.92 ± 2.59 t N/hm2, and 17.55 ± 1.54 t P/hm2 in the saltmarsh wetland versus 119.72 ± 27.88 t C/hm2, 4.38 ± 1.24 t N/hm2, and 13.17 ± 1.46 t P/hm2 in the riparian wetland. Therefore, wetland salinization in our study led to increased soil C, N, and P contents and storage and thereby enhanced the sink function of the wetlands.

Fine-Scale Distribution Patterns of Phragmites australis Populations Across an Environmental Gradient in the Salt Marsh Wetland of Dunhuang, China

The spatial distribution pattern of plants often reflects their ecological adaptation strategy and is formed by their long-term interaction with environmental factors. In this paper, the clonal plant, Phragmites australis, was investigated across environmental gradients, including the wet zone, the transitional zone and the desert zone of the salt marsh wetland of Dunhuang, China. The characteristics and influencing factors of their fine-scale spatial distribution patterns were studied by point pattern analysis, redundancy analysis and simple linear regression. The results show that: (1) the spatial distribution pattern of Phragmites australis changes from aggregation to non-aggregation (random and regular distribution) from the wet zone to the desert zone. (2) The soil water content, pH and salinity all affect Phragmites australis’ spatial distribution intensity. Simple linear regression reveals that the water content in each soil layer, the pH of the deep soil layer and the salinity of the surface and deep soil layers are the main soil conditions of Phragmites australis’ spatial distribution pattern. (3) Phragmites australis’ population characteristics and clonal characteristics also have significant effects on its spatial distribution intensity. Specifically, the intensity of its spatial distribution pattern is significantly positively correlated with its cover, frequency, density, height, biomass, node number, ramet number and stem diameter (p < 0.01), while it is significantly negatively correlated with its rhizome internode length, spacer length and branch angle (p < 0.01). This research clarified the relationship between the spatial distribution pattern of Phragmites australis with soil environmental factors, plant clonal characteristics and population characteristics. The results provide a theoretical basis for understanding the ecological adaptation mechanism of clonal plants and protecting the sustainability of fragile and sensitive inland river wetland ecosystems.

嘉峪关草湖湿地植物功能群组成及其性状对不同生境的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 嘉峪关草湖湿地植物功能群组成及其性状对不同生境的响应 DOI: 10.5846/stxb201811052396 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41861009） Responses of composition and functional traits of plant functional groups to different habitats in Jiayuguan Caohu Wetland Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:植物功能群与生境的关系是生态学研究的重要内容，对于揭示植物的环境适应机制、群落构建机制、预测植被变化等具有重要意义。为研究局域尺度上干旱区湿地、沙漠、戈壁等生态系统功能群的环境适应机制，在嘉峪关草湖国家湿地公园内，基于植物功能性状数据，研究了荒漠区不同生境条件下的功能群组成和功能性状特性。结果表明：随着生境条件的改变，土壤含水量、含盐量、容重、pH值等土壤性质发生显著变化；植物的功能群组成和功能性状会发生适应性的变化，沼泽湿地生境内植被的功能性状以克隆、C4光合途径、根茎型等特征为主，盐沼湿地以叶片被蜡、叶茎肉质、CS策略等特征为主，沙丘生境以叶片具毛、风播、具增厚或增长的根、一年生、CR策略等特征为主，荒漠戈壁以叶片少、具增厚或增长的根、虫媒、地上芽等特征为主。局域尺度上，生境异质性尤其是土壤条件的异质性是影响植物群落组成和植物功能性状变化的重要环境因子。 Abstract:The relationship between plant functional groups and habitats is an important topic of the research of ecology. It can reveal the mechanism of plant environmental adaption, community construction, and can predict the changes of vegetation. In order to study adaption of the functional groups to different habitats in the arid area such as wetland, desert and gobi on a local scale, the composition and functional traits of functional groups in different habitats of desert areas were studied in Jiayuguan Caohu National Wetland Park based on the data of plant functional traits. The results showed that, with the change of habitat conditions, the soil water moisture, salt content, bulk density, pH value and other soil properties changed significantly. The composition of plant functional groups and functional traits changed adaptively. The functional traits of vegetation in the marsh wetland were mainly clonal plant, C4 photosynthetic pathway, and rhizomatous plant. The salt marsh wetland were mainly wax-coating, leaf or stem succulence, and CS strategy type. Dune habitats were with hairiness, thickened or long roots, annual, and CR strategy type, while Gobi with reduced leaves, thickened or long roots, entomophilous, and chamaephyte. On the local scale, habitat heterogeneity, especially soil heterogeneity, is an important environmental factor affecting the composition of plant communities and the changes of plant functional traits. 参考文献 相似文献 引证文献

Study on water and salt balance of plateau salt marsh wetland based on time-space watershed analysis

We analysed the eco-hydrological characteristics of the Bojiang Haizi River basin, which is the location of the Erdos Larus Relictus Nature Reserve plateau salt marsh wetland. The study found that the restoration of the plateau salt marsh is more of a water quality problem than a water quantity problem. Simply maintaining the balance of water volume without considering water quality will destroy the original stable ecosystem. Therefore, water balance analysis was conducted for the overall water resources in the basin on the basis of simulated data of the Soil and Water Assessment Tool module. We examined remote sensing and water quality monitoring data via geographic information system-3D technology to meet the requirements of water quality and quantity in wetland restoration. We established the hydrological dynamic relationship model of lake storage capacity-elevation-area-salinity and found that the lake presents an alternating cyclic rule of salt accumulation and dilution during seasonal changes. This pattern is an important guarantee for the healthy and sustainable development of the salt marsh wetland. Lastly, the survival salinity of the organism was selected as the target salinity (5 g/L), and the corresponding target water amount was simulated as 20.17 × 106 m3; the target lake area was 9.48 km2. Through an analysis of three water transfer scenarios, we found that under the optimum balance condition between water quantity and salt concentration, simulating the water transfer mode in precipitation replenishment is an effective means to restore the wetland during breeding season. The findings of this study may improve our understanding of the eco-hydrological characteristics of plateau salt marsh wetlands and help managers protect and restore water balance using water–salt dynamic models.

Carbon outwelling and outgassing vs. burial in an estuarine tidal creek surrounded by mangrove and saltmarsh wetlands

AbstractMangrove‐ and saltmarsh‐dominated estuaries have high rates of organic carbon burial. Here, we estimate soil, pore water, and surface‐water carbon fluxes in an Australian estuarine tidal creek to assess whether (1) advective pore water exchange releases some of the soil carbon, (2) outwelling (lateral exports) represents a major carbon sequestration mechanism, and (3) methane emissions offset soil carbon sequestration. A radon (222Rn) mass balance implied tidally driven pore‐water exchange rates ranging from 5.5 ± 3.6 to 15.6 ± 8.1 cm d−1. Pore water exchange explained most of the dissolved organic carbon (DOC) and methane surface‐water fluxes but not dissolved inorganic carbon (DIC) and alkalinity. Organic carbon burial in soils derived from 239 + 240Pu dating was 11–63 g C m−2 yr−1. Methane and carbon dioxide emissions at the water–air interface were 0.27 ± 0.03 and 63 ± 166 mmol m−2 d−1, respectively. When calculated as CO2‐equivalents, aquatic CH4 emissions converted to 19–94 g C‐CO2 m−2 yr−1. Upscaling methane and soil carbon fluxes to representative areas revealed that CH4 emissions could offset < 5% of soil carbon burial. DIC outwelling (12 ± 6 mmol m−2 catchment d−1) was less than five‐fold greater than DOC and particulate organic carbon (POC) outwelling and four‐fold greater than catchment‐wide carbon burial. Because much of this DIC remains in the ocean after air–water equilibration, lateral DIC exports may represent an important long‐term carbon sink. Recent research has focused on quantifying carbon burial rates in blue carbon habitats such as saltmarshes and mangroves. We suggest that DIC outwelling and methane outgassing should also be considered when assessing the carbon sequestration capacity of these coastal vegetated habitats.

秦王川盐沼湿地芦苇叶片比叶面积与光合效率的关联分析

PDF HTML阅读 XML下载 导出引用 引用提醒 秦王川盐沼湿地芦苇叶片比叶面积与光合效率的关联分析 DOI: 10.5846/stxb201807271607 作者: 作者单位: 西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41461013，41861009） The correlation analysis between specific leaf area and photosynthetic efficiency of Phragmites australis in salt marshes of Qinwangchuan Author: Affiliation: Northwest Normal University,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,,, Fund Project: The Knowledge Innovation Program of the Chinese Academy of Sciences,China Postdoctoral Science Foundation,Joint Research Fund for Overseas Chinese Young Scholars 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:植物比叶面积（SLA）与光合效率的关联性分析，有助于理解植物叶片的光合产物分配与能量分配之间的权衡机制。该研究以秦王川国家湿地公园芦苇（Phragmites australis）种群为研究对象，沿芦苇群落末端至水域边缘分别依次设置：（I：土壤电导率（EC）2.3-2.8 ms/cm）、（Ⅱ：1.8-2.2 ms/cm）、（Ⅲ：0.8-1.5 ms/cm）3个试验样地，研究了秦王川盐沼湿地不同土壤盐分条件下芦苇叶片SLA与光合效率的关系。结果表明：随着土壤盐分含量的降低，湿地群落的高度、地上生物量逐渐增大，密度、光合有效辐射（PAR）呈逐渐减小的趋势；叶面积、株高、净光合速率（P < sub>n）、水分利用效率（WUE）和蒸腾速率（Tr）均呈逐渐增大的趋势，叶厚度逐渐减小，比叶面积呈先增加后减少的变化趋势，叶干重的变化趋势与比叶面积完全相反；芦苇叶片实际光合效率（Y（Ⅱ））、光化学淬灭系数（QP）和电子传递速率（ETR）呈先减少后增大的变化趋势，非光化学猝灭系数（NPQ）、调节性能量耗散的量子产额（Y（NPQ））和最大光化学效率（Fv/Fm）呈先增加后减少的变化趋势，非调节性能量耗散的量子产量（Y（NO））呈逐渐增大的变化趋势。在3个样地中，芦苇SLA与Y（Ⅱ）和ETR之间均呈极显著负相关关系（P < 0.01），SMA斜率的绝对值均呈先增大后减少的变化趋势。随土壤含盐量的梯度性变化，芦苇种群适时调整叶片构件模式以改变叶片电子传递速率和实际光化学效率，实现植物光合效率的最大化，反映了盐沼湿地植物的特殊生存策略和叶片构件模式。 Abstract:The analysis of the response of plant specific leaf area (SLA) and photosynthetic efficiency to soil salinity is helpful to understand the balance mechanism between photosynthetic product distribution and energy distribution in plant leaves. This study aims to examine the relationship between specific leaf area and photosynthetic efficiency of Phragmites australis in response to the soil salt gradient. The study area is located in Qinwangchuan National Wetland Park (36.47° N, 103.65° E), Gansu Province, China. The range of the selected site with the area of 100 m×100 m is from the edge to the central of the wetland, where the reed is the single dominant species. There are three sample plots set on the basis of the soil salt content. The results showed that with the soil salt content decreased gradually, the height of the wetland community and the ground biomass presented increasing trend correspondingly, while density, photosynthetic active radiation (PAR), and leaf thickness had the opposite trend. Plant height, leaf area, net photosynthetic rate (P < sub>n), transpiration rate (Tr), and water use efficiency (WUE) increased gradually, and the specific leaf area increased at the beginning and decreased afterwards, and leaf dry weight presented opposite trends compared with SLA. From plot I to plot Ⅲ, with the decreasing of the soil salt content, the effective quantum yield of PSⅡ photochemistry (Y(Ⅱ)), the photochemical quenching (QP), and the electron transport rate (ETR) firstly reduced then increased. The non-photochemical quenching (NPQ), the quantum yield of regulatory energy dissipation (Y(NPQ)), and the maximum efficiency of photosystem (PS) Ⅱ photochemistry (Fv/Fm) performed the increased-decreased changing trends. The quantum yield of non-regulatory energy dissipation (Y(NO)) showed increase trend. There were highly significantly negative correlation (P < 0.01) between SLA and Y(Ⅱ), and between SLA and ETR among three plots, and the absolute value of SMA slope firstly increased and then decreased. With the soil salinity gradient changes, the reeds species adjusted blade component model timely by changing ETR and Y(Ⅱ) to maximize plant photosynthetic efficiency, which reflected that the special survival strategy and leaf component model of plants in salt marsh wetland. 参考文献 相似文献 引证文献

Mechanisms and feedbacks for evapotranspiration-induced salt accumulation and precipitation in an arid wetland of China

Salt dissolved in soil water is transported upward to the soil surface through capillary rise from shallow groundwater, leading to salt accumulation near the surface and salinization of wetlands in arid regions. However, it is not clear how the mechanism and feedback for evapotranspiration induces salt accumulation and precipitation. Here, we developed a model to simulate the transport of water, solutes, and heat, and measured the meteorological, hydrological, and hydraulic parameters of soil using field experiments to calibrate the model for riparian and saltmarsh wetlands in northwestern China. The results showed that the annual atmospheric precipitation averaged 125.3 ± 10.2 mm in two types of wetlands, the evapotranspiration, depth to the groundwater and soil salinity averaged 587.7 mm yr−1, 85.4 ± 5.4 cm and 29.80 g kg−1 in the riparian wetland, while 637.2 mmyr−1, 129.7 ± 15.1 cm and 63.64 g kg−1 in the saltmarsh wetland, respectively. We found that the flux of liquid water, flux of water vapor, salinity, and efflorescence had maximum values of 1.23 mm day−1, 0.22 mm day−1, 104.16 g kg−1, and 2.10 cm in the riparian wetland, respectively, versus 1.28 mm day−1, 0.32 mm day−1, 202.02 g kg−1, and 3.70 cm in the saltmarsh wetland. Our simulations show that the salinity increases significantly with increasing evapotranspiration, soil temperature, saturated water content, and groundwater depth in the saltmarsh wetland, but that the effects of saturated water content and groundwater depth were small in the riparian wetland. As a result of these factors, the efflorescence pattern exhibited characteristic seasonal and inter-annual variability in which complex interactions among atmospheric precipitation, evapotranspiration, groundwater, and river water provided the long-term driving forces for water flow and salt transport. We found that the increasing efflorescence disrupted evaporation more than subflorescence, which reduced the soil porosity and possibly affected water vapor transport.

Expanding fish productivity in Tasmanian saltmarsh wetlands through tidal reconnection and habitat repair

Fish use of coastal saltmarsh wetlands has been documented for many parts of Australia with the notable exception of Tasmania. An initial investigation to examine the diversity, density and patterns of fish use in the Circular Head coast saltmarshes of north-west Tasmania was undertaken. To aid decision making in repair strategies, the effect of saltmarsh condition on fish assemblages was studied using paired sites of predominantly unaltered and altered saltmarshes where levees were present. In all, 851 fish from 11 species were caught in 37 of the 48 pop nets. Three species, Aldrichetta forsteri, Arripis truttaceus and Rhombosolea tapirina, are important to commercial and recreational fisheries and contributed ~20% of the total catch numbers. The mean density of &amp;gt;72 fish per 100m2 is the highest yet reported from Australian studies and indicates that Tasmanian saltmarshes provide higher value habitat for fish compared with elsewhere in Australia, likely due to more frequent and prolonged flooding, and the lack of adjacent mangroves. There was no significant difference in fish assemblages between unaltered and altered marshes. The results suggest that restoring basic saltmarsh structure through tidal reconnection will deliver substantial benefits for fish productivity through habitat expansion.A

Reduction of Manganese Oxides: Thermodynamic, Kinetic and Mechanistic Considerations for One- Versus Two-Electron Transfer Steps

Manganese oxides, typically similar to δ-MnO2, form in the aquatic environment at near neutral pH via bacterially promoted oxidation of Mn(II) species by O2, as the reaction of [Mn(H2O)6]2+ with O2 alone is not thermodynamically favorable below pH of ~ 9. As manganese oxide species are reduced by the triphenylmethane compound leucoberbelein blue (LBB) to form the colored oxidized form of LBB (λmax = 623 nm), their concentration in the aquatic environment can be determined in aqueous environmental samples (e.g., across the oxic–anoxic interface of the Chesapeake Bay, the hemipelagic St. Lawrence Estuary and the Broadkill River estuary surrounded by salt marsh wetlands), and their reaction progress can be followed in kinetic studies. The LBB reaction with oxidized Mn solids can occur via a hydrogen atom transfer (HAT) reaction, which is a one-electron transfer process, but is unfavorable with oxidized Fe solids. HAT thermodynamics are also favorable for nitrite with LBB and MnO2 with ammonia (NH3). Reactions are unfavorable for NH4+ and sulfide with oxidized Fe and Mn solids, and NH3 with oxidized Fe solids. In laboratory studies and aquatic environments, the reduction of manganese oxides leads to the formation of Mn(III)-ligand complexes [Mn(III)L] at significant concentrations even when two-electron reductants react with MnO2. Key reductants are hydrogen sulfide, Fe(II) and organic ligands, including the siderophore desferioxamine-B. We present laboratory data on the reaction of colloidal MnO2 solutions (λmax ~ 370 nm) with these reductants. In marine waters, colloidal forms of Mn oxides (< 0.2 µm) have not been detected as Mn oxides are quantitatively trapped on 0.2-µm filters. Thus, the reactivity of Mn oxides with reductants depends on surface reactions and possible surface defects. In the case of MnO2, Mn(IV) is an inert cation in octahedral coordination; thus, an inner-sphere process is likely for electrons to go into the empty e g * conduction band of its orbitals. Using frontier molecular orbital theory and band theory, we discuss aspects of these surface reactions and possible surface defects that may promote MnO2 reduction using laboratory and field data for the reaction of MnO2 with hydrogen sulfide and other reductants.

Electricity generation from different wetlands: Mechanisms based on dissolved organic matters in membrane-less microbial fuel cells

The membrane-less and biocathode-containing microbial fuel cells (MLBC-MFCs) were used for the electrical energy production from different wetlands, and the corresponding mechanisms were explored based on the characteristics of dissolved organic matters (DOM) in this study. The average voltage output on indoor MLBC-MFCs was 60 mV for the saltmarsh wetland water (SWW), 48 mV for the forest wetland water (FWW) and 71 mV for the FWW supplemented with sodium chloride (FWWS). For the field experiments, as high as 800 mV was obtained from the MLBC-MFCs installed in the forest wetland and the voltage output varying between 200 mV and 800 mV maintained approximately for half a year except for a few days with an extremely low temperature, while the voltage output from the MLBC-MFCs installed in the saltmarsh wetland went down to below 10 mV within 37 days likely due to the tide. The DOM before and after MFCs treatment was analyzed using the ultraviolet–visible absorption spectroscopy (UV–Vis) and the fluorescence excitation-emission matrix (EEM). Results showed that both carbon sources and anaerobic microorganisms included in subaqueous wetland sediments (SWSs) were vital for the electricity generation, and the food used to produce electrical energy mainly came from SWSs instead of wetlands water.

秦王川盐沼湿地角果碱蓬种群聚集分布格局与特征

PDF HTML阅读 XML下载 导出引用 引用提醒 秦王川盐沼湿地角果碱蓬种群聚集分布格局与特征 DOI: 10.5846/stxb201705020810 作者: 作者单位: 西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41461013，91125014）；甘肃省生态学重点学科基金项目 Aggregated spatial patterns and characteristics of Suaeda corniculata in Qin wangchuan salt marsh Author: Affiliation: Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:植物种群的多尺度集聚与聚块特征变化是植物对环境协同适应的结果。运用成对相关函数与零模型方法，依据微地形的土壤盐分分布规律设置4个样地，在2 m×2 m的样方内设置400个小格子记录植物株数并取土样，分析了兰州秦王川盐沼湿地土壤盐分梯度下角果碱蓬种群（Suaeda corniculata）种群空间格局的集聚分布内在特征。结果表明：角果碱蓬种群集聚分布范围内呈现2个关键尺度的集聚现象，小尺寸聚块的集聚或叠加形成复合大尺度聚集，整体表现为嵌套双聚块分布；随着土壤盐分递减，种群集群分布中大聚块尺寸趋于增大，小聚块尺寸差异不明显；大尺寸聚块的数量明显减少，小聚块数量随种群植株数量变化，整个梯度呈现降低趋势；小聚块中植株个体平均数逐渐减少，复合大聚块中包含小尺度聚块平均数量呈降低趋势。内陆盐沼湿地土壤环境异质性背景下角果碱蓬种群集群分布中聚块特征的梯度变化，是植株个体形态与构成的调整适应，种群正负向生态关系、庇护与自疏效应梯度转换的结果。 Abstract:Multiple clustering of plant populations and variation in cluster characteristics is the result of collaborative adaptation by plants to the environment. According to the distribution of soil salinity in micro-topography, the experimental set up was four 2 m×2 m sample plots. Each sample was divided into 400 cells, the number of plants was recorded, and soil samples were collected. Using the null model, the data were analyzed for aggregated spatial patterns and characteristics of the Suaeda corniculata population in the Qin wangchuan salt marsh in Lanzhou city. The results showed that:Suaeda corniculata populations showed a complex spatial pattern with two critical scales of clustering, small-scale clustering was assembled into composite large-scale clustering through superposition and aggregation, and populations showed the nested double-cluster process at all scales. As the soil salinity decreased, the size of large-scale clusters tended to increase and the size of small-scale clusters did not show obvious differences. The number of large-scale clusters decreased significantly, and the number of small-scale clusters tended to increase with the increase in size of the plant population in the whole study area. The average number of plants in one small-scale cluster gradually reduced, and the average number of small clusters in one large cluster showed a decreasing trend, which were related to gradually reduce of the soil salinity. Under the background of soil environmental heterogeneity in the inland saltmarsh wetland, the gradient of variation in clustering characteristics was the adjustment of plant individual form and composition. It was also the result of gradient transformation of the population ecology relationship, protection, and self-thinning effects. 参考文献 相似文献 引证文献

A Field Study of How Wind Waves and Currents May Contribute to the Deterioration of Saltmarsh Fringe

Deltaic landscapes, such as the Mississippi River Delta, are sites of extensive conversion of wetlands to open water, where increased fetch may contribute to erosion of marsh edges, increasing wetland loss. A field experiment conducted during a storm passage tested this process through the observations of wave orbital and current velocities in the fringe zone of a deteriorating saltmarsh in Terrebonne Bay, Louisiana. Incident waves seaward of the marsh edge and wave orbital and current velocities immediate landward of the marsh edge were measured. Through a dimensional analysis, it shows that the current and orbital velocities in the marsh fringe were controlled by the incident waves, inundation depth, submergence ratio, and vegetation density. Similarly, it is shown that the longshore currents in the inundated saltmarsh fringe depended on the local wave-induced momentum flux, vegetation submergence, and vegetation density in the fringe zone. The cross-shore current showed the presence of a return flow in the lower region of the velocity profile. A high correlation between the current direction and the local flow-wave energy ratio as well as the vegetation submergence and density is found, indicating the important role of surface waves in the fringe flow landward of an inundated wetland under storm conditions. The field observations shed light on the potential ecological consequences of increased wave activities in coastal saltmarsh wetlands owing to subsidence, sea level rise, limited sediment supply, increases in wind fetch, and storm intensity.

Detecting wetland changes in Shanghai, China using FORMOSAT and Landsat TM imagery

Summary Understanding the state of wetland ecosystems and their changes at the national and local levels is critical for wetland conservation, management, decision-making, and policy development practices. This study analyzed the wetlands in Shanghai, a province-level city, using remote sensing, image processing, and geographic information systems (GIS) techniques based on the Chinese national wetland inventory procedure and standards. FORMOSAT imagery acquired in 2012 and Navy nautical charts of the Yangtze estuarine area were used in conjunction with object-oriented segmentation, expert interpretation, and field validation to determine wetland status. Landsat imagery from 1985, 1995, 2000, 2003 and 2013 as well as social-economic data collected from 1985 to 2013 were used to further assess wetland changes. In 2013, Shanghai contained 376970.6 ha of wetlands, and 78.8% of all wetlands were in marine or estuarine systems. Estuarine waters comprised the single largest wetland category. Between the first national wetland inventory in 2003 and the second national wetland inventory in 2013, Shanghai lost 50519.1 ha of wetlands, amounting to a mean annual loss rate of 1.2% or an 11.8% loss over the decade. Declines were proportionately higher in marine and estuarine wetlands, with an annual loss of 1.8%, while there was a sharp increase of 1882.6% in constructed water storage areas for human uses. Diking, filling, impoundment and reclamation, which are all attributable to the economic development and urbanization associated with population increases, were the major factors that explained the gain and loss of wetlands. Additional factors affecting wetland losses and gains include sediment trapping by the hydropower system, which reduces supply to the estuary and erodes wetlands, and sediment trapping by the jetties, spur dikes, and diversion bulwark associated with a navigation channel deepening project, which has the converse effect, increasing saltmarsh wetland area at Jiuduansha shoal by three times between 2000 and 2013.

Experimental observations on sediment resuspension within submerged model canopies under oscillatory flow

A set of laboratory experiments were conducted to study the effect of submerged aquatic vegetation in sediment resuspension under progressive waves. Three vegetation models (rigid, flexible and real plants of Ruppia maritima), six wave frequencies (in the range F=0.6–1.6Hz) and four plant densities (Solid Plant Fractions, SPF in the range of 1–10%) were used. The sediment bed properties corresponded to a salt marsh wetland with a bimodal particle size distribution with two particle populations (population 1: particle diameters in the range of 2.5 to 6.0μm, and population 2: particle diameters in the range of 6.0 to 100μm).Within the canopy, wave velocities were attenuated for all the canopies studied and for all the frequencies analyzed. The change in the TKE (ΔTKE) compared with the case without plants was studied. For the rigid canopy model, in comparison to the unimpeded experiment, an increase in ΔTKE inside the canopy for smaller frequencies (F=0.6–1.2Hz) was observed together with stem Reynolds numbers Rep above 250. As a result, sediment resuspension for both sediment populations was higher than that of the unimpeded experiment. However, at higher frequencies (F=1.4 and 1.6Hz) and higher plant densities (SPF=5%, 7.5% and 10%), the ΔTKE inside the canopy decreased, coinciding with stem Reynolds number Rep below 250. As a result, sediment resuspension for larger canopy densities and larger frequencies was reduced.For the flexible vegetation model, in comparison with the unimpeded experiment, a reduction in the ΔTKE inside the canopy was nearly always found. Resuspended sediment concentrations were found to decrease as flexible canopy densities increased. For the flexible vegetation the stem Reynolds number was Rep<250 and no production of ΔTKE was observed. The real case of a canopy of R. maritima behaved similarly to the flexible model canopy.

Distribution and deposition characteristics of carbon and nitrogen in sediments in a semi-closed bay area, southeast China

In this study, we analyzed carbon and nitrogen parameters (e.g., total organic carbon (TOC), total nitrogen (TN), stable isotopes of organic matter (δ13C, δ15N), and carbon–nitrogen ratio (C/N)), grain-size parameters and deposition rate, as well as their variations in the surface layer and on the profile of the sediment cores in various ecological zones of Luoyuan Bay. The results showed that the sedimentary type of Luoyuan Bay was clay silt. The TOC, TN, δ13C, and δ15N were in the range of 0.450–0.955%, 0.054–0.101%, −23.75 to −19.47‰, and 3.57–6.72‰, respectively; the C/N was in the range of 8.80–13.78. The grain-size parameters of the Spartina alterniflora marsh and transition zone were similar, whereas a similarity in the carbon and nitrogen parameters between the transition zone and mudflat was observed. The correlation of TOC and TN was different between the fresh organic matter and the obsolete organic matter. The particle size was not the main factor that controlled the TOC and TN contents in the sediments; the δ13C indicated the organic matter was dominated by marine sources. The average deposition rates in the Spartina alterniflora marsh, transition zone, and mudflat were 2.47, 2.79, 1.16gcm−2y−1, respectively. In the Spartina alterniflora marsh, the TOC and TN content increased by 96% and 104%, respectively, from 1955 to the present. Compared with the mudflat, the TOC and TN content in the layer between the surface and the 40-cm depth of the Spartina alterniflora marsh were 26% and 13% higher, respectively. The introduction of Spartina alterniflora and the metabolism of their roots had a significant effect on the carbon and nitrogen deposition in the layer at 0–40cm depth. The carbon sequestration rate of the salt marsh wetland in Luoyuan Bay was comparable to the carbon sequestration of global marshes. The deposition rates of TOC and TN in the Spartina alterniflora marsh and transition zone were greater than twice that in the mudflat.

VEGETATION SYNTAXONOMY AND LAND MANAGEMENT EFFECT ON METHANE AND CARBON DIOXIDE EMISSIONS FROM WETLANDS: A CASE STUDY FROM TIDAL SALT AND BRACKISH MARSH

Carbon dioxide (CO 2 ) and methane (CH 4 ) emission from wetlands significantly contribute to climate change and global warming. The interaction between among vegetation type, various environmental factors, and management regimes such as grazing and mowing is considered important in the calculation of CO 2 and CH 4 gas flux for an ecosystem. In this study, vegetation composition, CH 4 and CO 2 flux, soil characteristics, air temperature and humidity from the brackish marsh and salt marsh wetland ecosystems on Terschelling Island in Northern Holland were measured. We aimed to investigate the relationship between vegetation composition, grazing, and mowing on CH 4 and CO 2 emission. The abundance and number of plant species were higher in brackish than in salt marsh. Grazing was found to influence species richness, 39 species being found in a grazed site of brackish marsh compared to 31 species in a similar ungrazed site. CO 2 fluxes in salt and brackish marsh were found to be similar while CH 4 flux in the salt marsh was found to be lower than in the brackish marsh. Within the brackish marsh, a higher methane emission was recorded in the grazed zone. However the overall effect of grazing and mowing was found to be negligible for CH 4 flux but is suggested to clearly reduce CO 2 flux in both the salt and brackish marsh.

Variability of polychaete secondary production in intertidal creek networks along a stream-order gradient.

Dendritic tidal creek networks are important habitats for sustaining biodiversity and ecosystem functioning in salt marsh wetlands. To evaluate the importance of creek heterogeneity in supporting benthic secondary production, we assess the spatial distribution and secondary production of a representative polychaete species (Dentinephtys glabra) in creek networks along a stream-order gradient in a Yangtze River estuarine marsh. Density, biomass, and secondary production of polychaetes were found to be highest in intermediate order creeks. In high order (3rd and 4th) creeks, the density and biomass of D. glabra were higher in creek edge sites than in creek bottom sites, whereas the reverse was true for low order (1st and 2nd) creeks. Secondary production was highest in 2nd order creeks (559.7 mg AFDM m−2 year−1) and was ca. 2 folds higher than in 1st and 4th order creeks. Top fitting AIC models indicated that the secondary production of D. glabra was mainly associated with geomorphological characters including cross-sectional area and bank slope. This suggests that hydrodynamic forces are essential factors influencing secondary production of macrobenthos in salt marshes. This study emphasizes the importance of microhabitat variability when evaluating secondary production and ecosystem functions.

Environmental change in a Mediterranean salt marsh wetland: ecological drivers of halophytes diversity along flooding frequency gradients

Environmental change in a Mediterranean salt marsh wetland: ecological drivers of halophytes diversity along flooding frequency gradients

Spectral Discrimination of the Invasive Plant Spartina alterniflora at Multiple Phenological Stages in a Saltmarsh Wetland

Spartina alterniflora has widely invaded the saltmarshes of the Yangtze River Estuary and brought negative effects to the ecosystem. Remote sensing technique has recently been used to monitor its distribution, but the similar morphology and canopy structure among S. alterniflora and its neighbor species make it difficult even with high-resolution images. Nevertheless, these species have divergence on phenological stages throughout the year, which cause distinguishing spectral characteristics among them and provide opportunities for discrimination. The field spectra of the S. alterniflora community as well as its major victims, native Phragmites australis and Scirpus mariqueter, were measured in 2009 and 2010 at multi-phenological stages in the Yangtze River Estuary, aiming to find the most appropriate periods for mapping S. alterniflora. Collected spectral data were analyzed separately for every stage firstly by re-sampling reflectance curves into continued 5-nm-wide hyper-spectral bands and then by re-sampling into broad multi-spectral bands – the same as the band ranges of the TM sensor, as well as calculating commonly used vegetation indices. The results showed that differences among saltmarsh communities’ spectral characteristics were affected by their phenological stages. The germination and early vegetative growth stage and the flowering stage were probably the best timings to identify S. alterniflora. Vegetation indices like NDVI, ANVI, VNVI, and RVI are likely to enhance spectral separability and also make it possible to discriminate S. alterniflora at its withering stage.