2010—2012年，采用野外采样和实验室测定相结合的方法,研究了长江口九段沙芦苇、互花米草植被带生物量的季节动态和碳储存能力.结果表明： 两种植物生物部分(地上、地下、枯立物生物量之和)的有机碳储量均为秋季最高、春季最低.地上活体互花米草单位面积的平均碳储量(445.81 g·m^-2)高于芦苇(285.52 g·m^-2)，芦苇枯立物的平均碳储量(203.15 g·m^-2)低于互花米草(315.28 g·m^-2)，但芦苇区土壤表层(0～30 cm)有机碳储量(1048.62 g·m^-2)约为互花米草区(583.33 g·m^-2)的2倍.芦苇区的碳储存能力(3212.96 g·m^-2)总体上高于互花米草区(2730.42 g·m^-2).表明保护芦苇群落对于维护盐沼湿地的碳汇功能具有重要意义.

By the methods of field survey and laboratory analysis, an investigation was conducted on the seasonal dynamics of biomass and carbon storage of <em>Phragmites australis</em> and<em> Spartina alterniflora</em> dominated vegetation belts in the Jiuduan Shoal Wetland of Yangtze Estuary, East China in 2010-2012. The organic carbon storage of the biomass (including aboveground part, underground part, and standing litter) of the two plants was the highest in autumn and the lowest in spring. The average carbon storage of the biomass of <em>S. alterniflora</em> per unit area (445.81 g&middot;m^-2) was much higher than that of <em>P. australis</em> (285.52 g&middot;m^-2), and the average carbon storage of the standing litter of<em> S. alterniflora</em> (315.28 g&middot;m^-2) was also higher than that of <em>P. australis</em> (203.15 g&middot;m^-2). However, the organic carbon storage in the surface soil (0-30 cm) under <em>P. australis</em> community (1048.62 g&middot;m^-2) was almost as twice times as that under <em>S. alterniflora</em> community (583.33 g&middot;m^-2). Overall, the carbon accumulation ability of <em>P. australis</em> community (3212.96 g&middot;m^-2) was stronger than that of the <em>S. alterniflora</em> community (2730.42 g&middot;m^-2). Therefore, it is of significance to protect the <em>P. australis</em> community in terms of carbon sequestration at the salt marsh.

滨海盐沼湿地有着较高的碳沉积速率和固碳能力,在缓解全球变暖方面发挥着重要作用,而盐渍土壤是滨海盐沼湿地碳收支研究中最大的有机碳库,研究其碳沉积与埋藏对于理解滨海湿地碳收支有着重要的意义.本文从滨海盐沼湿地土壤有机碳的来源、土壤有机碳库与沉积速率、盐沼湿地有机碳的埋藏机制、全球变化与滨海盐沼湿地碳封存等几方面对滨海盐沼湿地有机碳沉积与埋藏的相关研究进行综述.今后研究应侧重:1)加强对控制滨海盐沼湿地碳储存变异的基本因素的进一步研究；2)对测量滨海盐沼湿地沉积物碳储量和沉积碳埋藏速率的方法进行标准化；3)对潮汐影响下滨海盐沼湿地碳与邻近生态系统之间的横向交换通量进行量化；4)探明全球变暖的影响和生产力的提高是否可以抵消因呼吸增强而造成的有机碳降解速率的升高.确定固碳速率变化驱动因子,理解气候变化和人类活动对碳埋藏的影响机制,有助于提升我国滨海盐沼湿地的固碳能力.

Coastal salt marsh has higher potential of carbon sequestration, playing an important role in mitigating global warming, while coastal saline soil is the largest organic carbon pool in the coastal salt marsh carbon budget. To study the carbon deposition and burial in this soil is of significance for clearly understanding the carbon budget of coastal salt marsh. This paper summarized the research progress on the deposition and burial of organic carbon in coastal salt marsh from the aspects of the sources of coastal salt marsh soil organic carbon, soil organic carbon storage and deposition rate, burial mechanisms of soil organic carbon, and the relationships between the carbon sequestration in coastal salt marsh and the global climate change. Some suggestions for the future related researches were put forward: 1) to further study the underlying factors that control the variability of carbon storage in coastal salt marsh, 2) to standardize the methods for measuring the carbon storage and the deposition and burial rates of organic carbon in coastal salt marsh, 3) to quantify the lateral exchange of carbon flux between coastal salt marsh and adjacent ecosystems under the effects of tide, and 4) to approach whether the effects of global warming and the increased productivity could compensate for the increase of the organic carbon decomposition rate resulted from sediment respiration. To make clear the driving factors determining the variability of carbon sequestration rate and how the organic carbon storage is affected by climate change and anthropogenic activities would be helpful to improve the carbon sequestration capacity of coastal salt marshes in China.

Massive seawall construction in coastal wetlands threatens biodiversity

The biotic resistance hypothesis proposes that biotic interactions, such as competition and herbivory, resist the establishment and spread of non-native species. The relative and interactive role of competition and herbivory in resisting plant invasions, however, remains poorly understood. We investigated the interactive role of competition and herbivory (by the native rodent Rattus losea) in resisting Spartina alterniflora (cordgrass) invasions into mangrove forests. In southern China, although exotic cordgrass numerically dominates intertidal mudflats and open gaps in mangrove forests, intact forests appear to be highly resistant to cordgrass invasion. A field transplant and rodent exclusion experiment showed that while the impact of rodent grazing on cordgrass was weak on mangrove forest edges and open mudflats, rodent grazing strongly suppressed cordgrass in mangrove understory habitats. A greenhouse experiment confirmed a synergistic interaction between grazing and light availability (a proxy for mangrove shading and light competition) in suppressing cordgrass establishment, with the strongest impacts of grazing in low light conditions that likely weakened cordgrass to survive and resprout. When both were present, as in mangrove understory habitats, grazing and low light acted in concert to eliminate cordgrass establishment, resulting in resistance of mangrove forests to cordgrass invasion. Our results reveal that grazing by native herbivores can enhance the resistance of mangrove forests to cordgrass invasion in southern China, and suggest that investigating multifactor interactions may be critical to understanding community resistance to exotic invasions.© 2018 by the Ecological Society of America.

Large protected areas, once successful in rescuing iconic wetlands from human activities, are undermined by plant invasions.

盐沼湿地具有很高的碳捕获与存储能力, 是缓解全球变暖的有效蓝色碳汇(蓝碳)。未来气候变暖和海平面上升可能增加盐沼湿地的固碳能力, 其蓝碳功能越来越受到国际社会的重视。该文重点围绕盐沼湿地蓝碳形成的关键过程、光合碳分配过程及影响机制、碳沉积埋藏特征及其来源解析、盐沼湿地土壤碳库稳定性及其微生物机制、盐沼湿地蓝碳过程动态模拟及其增汇潜力等5个方面进行综述。在此基础上, 针对当前研究的不足, 提出今后的研究中需要进一步探究盐沼湿地植被海陆梯度分布格局对碳吸收能力和碳分配的影响, 土壤有机碳沉积和埋藏速率及其对全球变化的响应, 盐沼湿地土壤碳库的稳定性及其横向碳流动, 气候变化和海平面上升背景下盐沼湿地蓝碳模拟与增汇潜力评估, 以及盐沼湿地蓝碳的增汇技术和途径。以期为深入理解盐沼湿地蓝碳形成过程与机制, 预测全球变化背景下盐沼湿地蓝碳功能的潜在变化趋势和制定蓝碳增汇途径提供理论支持, 助力碳达峰、碳中和目标实现。

全球气候变化对资源、生态和环境的负面影响日益显现，降低大气CO₂浓度已经成为全球关注的焦点。潮间带湿地（如红树林和盐沼）具有很强的碳汇功能，是降低CO₂浓度和减缓全球气候变化的重要途径。红树林和盐沼作为重要的海岸带蓝碳生态系统，其土壤具有极高的储碳能力。由于受潮汐和降雨等驱动力的控制，红树林和盐沼土壤间隙水碳交换过程在海岸带蓝碳汇估算中具有较大的不确定性。同时，红树林和盐沼间隙水碳交换过程也是海岸带蓝碳汇相关研究中的前沿性科学问题，具有较大的挑战性。红树林和盐沼间隙水交换促使大量沉积物中的碳输出并存储于海洋，其可能是除了湿地碳埋藏之外的另一个重要碳汇，但目前对此尚未开展系统研究。总结论述了红树林和盐沼生境土壤间隙水交换速率及其携带蓝碳通量和控制因素，期望在对全球红树林和盐沼生态系统蓝碳收支和碳汇潜力进行评估中对其土壤间隙水过程携带的蓝碳通量引起足够的重视。这将深化对红树林和盐沼生态系统碳收支平衡和循环过程的认识，进而在全球气候变化的背景下，为更好地发挥海岸带蓝碳汇功能、促进红树林和盐沼生态系统建设和保护以及海岸带可持续发展提供科学支撑。

The negative impact of global climate change on resources, ecology, and the environment is becoming increasingly apparent. Hence, reducing the atmospheric carbon dioxide (CO₂) concentration has become a global concern. Intertidal wetlands (e. g., mangroves and salt marshes) have strong carbon sink functions that can reduce the CO₂ concentration, thus mitigating global climate change. Mangroves and salt marshes are important coastal blue carbon ecosystems characterized by high soil carbon storage. Porewater exchange and associated carbon exchange driven by tides and rainfall in mangroves and salt marshes are challenging issues when estimating the effects of coastal blue carbon sinks. Large amounts of porewater-derived sediment carbon outwellings remain in the ocean and may represent an important carbon sink; however, they are poorly understood, despite being potentially significant components of the salt marsh carbon budget. This review aims to quantify the porewater exchange rate and related carbon fluxes, analyze their driving mechanisms, and reassess the carbon budgets and carbon sink potentials of mangroves and salt marshes. This study promotes understanding the carbon balance and cycle processes associated with mangrove and salt marsh ecosystems, and provides a scientific basis for the construction, protection, and sustainable development of coastal blue carbon sinks in the context of global climate change.

通过对植物群落实地调查和室内相关指标测定，对崇明岛滨海湿地植物群落固碳的时间动态与分布格局进行了研究。结果表明：崇明岛滨海湿地植物群落大致分为芦苇（Phragmites australis）、海三棱藨草（Scirpus mariqueter）和互花米草（Spartina alterniflora）3种类型；芦苇生长高峰为3&mdash;5月，年固碳能力为(1.02&plusmn;0.12) kg&middot;m^-2&middot;a^-1，未围垦滨岸均有分布，其中北岸植株生物量最低，出叶后生物量动态变化可用叶氮含量高低表征；海三棱藨草3&mdash;5月快速生长，6月初生长稍停滞，后继续增长，年固碳能力为(0.33&plusmn;0.05) kg&middot;m^-2&middot;a^-1，集中于南岸；互花米草7&mdash;9月为生长高峰，年固碳能力为(1.32&plusmn;0.10) kg&middot;m^-2&middot;a^-1，分布于北湖以东至东滩，其种群扩张严重威胁当地生物多样性；崇明岛滨海湿地植物群落年固定CO₂量为2.5&times;10⁵ t&middot;a^-1，其中南岸湿地年固碳较为丰富，年固碳的快速积累发生在4&mdash;7月。可见，崇明岛滨海湿地植物群落具较强固碳功能，且存在明显的时空动态，对上海市碳增汇减排具有重要作用。

Sedimentary organic carbon accumulation rate in continental margin seas is more than one order higher than that of the oceans. Ocean margins play a very important role in global carbon budget since about 80% of terrestrial and marine organic carbon buried in the continental shelves. Of the Arctic Ocean total area over 30% is shelf, and it is accounted for one-fourth of global shelf area. Because of its ice cover biological pump in the Arctic Ocean was thought to be very limited, thus it has not been considered as a sink of carbon dioxide. With the recent observation of global warming, decreasing of ice cover in shelf area would lead to potential simulate primary production, thus increase sedimentary organic carbon accumulation rate in the shelves. In this review paper, organic carbon sources, riverine discharge of sediment and nutrients, sea ice cover variation, and biological pump were discussed in order to evaluation potential increasing of sedimentary organic carbon accumulation in the arctic shelves under global warming.

The total area of coastal wetlands exceeds 5000 km² in Jiangsu Province, China, but it has been decreasing rapidly as a result of intense reclamation activities. Two types of plants, Spartina angelica and Spartina alterniflora, were introduced successively into the Jiangsu coast, in order to protect the coastline from erosion and to increase the accumulation rate. ²¹⁰Pb and ¹³⁷Cs analyses were carried out for sediment samples from the salt marshes of Wangang, to derive the sedimentation rate, on the basis of an evaluation of the background values and factors affecting the enrichment of ²¹⁰Pb. Analysis of a typical sediment column of the tidal flat shows that the absorption of ²¹⁰Pb in the silt-dominated sediment is weak. Influences of storm events, bioturbation, material sources and analytical error also have an effect. As a result, some abnormal data points are present. These data were removed before the calculation of the sedimentation rate. The sedimentation rate was 3.3 cm a^-1 on average. Based upon analysis of the ¹³⁷Cs dating, the rate since 1963 was 3.1 cm a^-1 on average, similar to the data by ²¹⁰Pb dating and from previous studies.