Did you know? February 2, 2022, the second day of the first lunar month of the Year of the Tiger, is the 26th World Wetlands Day. The theme of this year's World Wetlands Day is "Cherishing Wetlands, Where People and Nature Coexist in Harmony", and this year is also the 30th year that China has joined the global Convention on Wetlands.
World Wetlands Day @ United Nations website
In Shanghai, from the mouth of the Yangtze River to the mouth of the Qiantang River, both the area of wetland vegetation and the species of wetland waterbirds are increasing significantly. Jiefang Daily Shangguan News reporter learned that behind this largest "green lung", East China Normal University led the national key research and development plan of "ecological restoration and industrialization technology of typical estuarine wetlands in the Yangtze River Delta", and joined hands with Shanghai Jiao Tong University, Tongji University, Nanjing University, Shanghai Ocean University and other teams to cultivate and protect wetlands all year round, and aim at the "double carbon" goal to provide solutions for global wetland carbon sequestration.
Chongming Dongtan wetland waterbirds spend the winter here. Photo by Wu Wei
Crack multiple natural mysterious "fairy circles"
Accelerate the restoration of large-scale wetland vegetation
Winter and spring, Chongming Dongtan Wetland, water birds in the reserve for winter, only to see white cranes and herons flying, wild ducks and swans swimming, large pieces of reeds dancing with the wind.
In the Chongming Dongtan Wetland Demonstration Area, the vegetation area has increased from 340 mu in 2017 to 1450 mu in 2020, which is still expanding; the secondary prevention and control of alien species of interflower rice grass has been combined with the regulation of water, sand, salt and vegetation in the embankment, and the wetland ecosystem has gradually improved and stabilized, and the number of birds crossing the border for winter has increased significantly...
These changes are closely related to the cracking of the diffusion mechanism of salt marsh vegetation in the Yangtze River estuary. It is from 2017 that the estuarine coastal research team of East China Normal University has carried out research experiments such as the restoration of dominant species in salt marsh wetlands under natural conditions at the mouth of the Yangtze River. The natural formation of the "elf circle" on the salt marsh wetland has attracted the attention of the research team, and the tough structure of this mysterious "elf circle" can greatly promote the formation of contiguous vegetation, and it has a strong ecological restoration ability. Through a large number of in situ investigation and control experiments, the research team of East China Normal University cracked the two ecological mechanisms formed by the "elf circle" and carried out long-term quantitative experimental research from the aspects of seed diffusion, rhizome propagation, and tidal dynamic conditions.
The population of Sea Triangular Grass was restored at Nanhui East Beach, and the density coverage was close to that of natural salt marsh after 3 months
In fact, the nanhui biantan salt marsh wetland ecosystem also self-organized to form a "fairy circle". The team at Shanghai Ocean University applied a number of technologies to the Nanhui Biantan Demonstration Zone. For example, in the natural tidal flats with strong hydrodynamic power, the use of degradable materials to assist the sowing technology has successfully restored the population of triangular grass. Today, the vegetation area of the demonstration area has expanded from 200 mu to 500 mu, the species and density of fish and benthic animals have been greatly improved, and a large number of water birds have been attracted, and the coastal protection function has been enhanced, and tourists have flocked to it.
The ancient poem "Yerba Buena Parrot Island", Shanghai Jinshan has a newly restored Parrot Island ecological wetland, not only with vast reeds, but also a paradise for birds. Through the introduction of related technologies, the species of waterbirds here have increased from 15 in 2017 to 100 in 2021, and the artificial restoration of wetlands has doubled the carbon sink capacity of natural tidal flat wetlands. After the relevant research results were published, they were recommended by the journal Nature as a highlight.
The project team of the National Key R&D Program of "Ecological Restoration and Industrialization Technology of Typical Estuarine Wetlands in the Yangtze River Delta" is in Nanhui Dongtan
Change "one-size-fits-all" eradication to hierarchical utilization
The problem of mutual flower rice grass invasion has spawned an industrial chain
Protecting wetlands also requires protecting native populations. As an invasive alien species, erythrophyllum has a large biomass, high salinity content, and repeated invasions, making it difficult to use and control. In fact, "in the context of the 'double carbon' strategy, the carbon sink potential of interfluous rice grass is also very impressive," said Li Xiuzhen, project leader and researcher of the State Key Laboratory of Estuarine Coastal Science of East China Normal University, "So in the future, we should continue to strengthen the exploration of the combination of 'control-utilization' governance to maximize the green development of the coastal economy."
Originally, the native vegetation of the Yangtze River Estuary wetland not only provided food for fish and benthic animals, but also provided foraging and habitat for birds. However, the alien species of interflower rice grass is tall and dense, and also encroaches on the growth territory of the native species, the sea triangular grass, which is difficult for birds to use to hide and feed, and the function of wetlands as a habitat for water birds declines.
Monitor elevation changes during wetland vegetation restoration
The research team started from the development and utilization of straw, spawned the industrial chain, and provided a new solution for the treatment of interflower rice grass. A number of colleges and universities have jointly tackled key problems, and a multi-level ecological industry chain with considerable economic benefits has been called out. The team of Tongji University has independently developed a portable energy self-sustaining straw carbonization miniaturization equipment to convert the straw of large wetland plants into biochar. Biochar has a strong adsorption capacity and can be used in agriculture, environmental protection, energy, chemical and other fields. Miniaturization equipment can be placed on a container of 6 meters × 2.4 meters, and transported to the location where the straw is processed in situ, which not only saves external energy consumption, but also saves a large amount of straw transportation costs.
The research team also mixed biochar with river dredging sediment, added appropriate excipients, and formed high-strength, porous ecological revetment materials and water purification materials through low-temperature, moist and thermal processing technology. Related products are applied to The North Yokogawa and Jinshan Aquaculture Bases of Chongming Dongtan, which solves the problems of a large number of wetland straws that are difficult to treat, dredging sediment that has nowhere to pile, collapse of the slope of the water bank and deterioration of water quality, and has achieved remarkable results.
Researchers measured water power at the leading edge of the vegetation light beach in Chongming East Beach
Researchers from Nanjing University also broke through the desalination bottleneck of the stalks by extracting the biological mineral liquid from the stalks of erythroxylum. After desalting, the residue still has a high crude protein content, and in addition to being used directly as feed or biochar production, it can also be used as a mushroom farming substrate. According to the energy analysis and calculation, a complete industrial chain of interflower rice grass can reach 29 production and investment ratio, and the economic benefits are considerable.
More importantly, the harvest site of interfluille rice grass can be used by a variety of water birds during migratory bird migration. The team observed along the coast of northern Jiangsu and found that the harvest sites had the largest number of waterbird species and numbers during the wintering period in January. Therefore, through proper utilization and management, the goal of "preventing Taiwan in summer, utilizing in autumn, and attracting birds in winter and spring" can be achieved, which has higher economic benefits, ecological benefits and generalizability than complete eradication.
Schematic diagram of carbon cycle of blue carbon ecosystem in typical coastal wetland (courtesy of Tang Jianwu et al.)
Accurate monitoring and quantitative evaluation of "blue carbon"
Ecological restoration and carbon sequestration are not wrong
Between the rivers and the sea, there is green carbon and blue carbon. The carbon fixed by coastal plants such as coastal salt marsh wetlands, mangroves and seagrass beds is called coastal zone blue carbon. "Blue carbon" is the process, activity and mechanism that uses marine activities and marine life to absorb carbon dioxide from the atmosphere, fix it and store it in the ocean.
However, the blue carbon research of coastal wetlands faces the problem of unclear carbon background and lack of accurate monitoring and quantitative assessment methods. Led by Professor Tang Jianwu, the blue carbon team of East China Normal University is one of the earliest teams in China and the world to study the carbon cycle in the coastal zone. The team took the lead in establishing a blue carbon monitoring network and big data platform for coastal wetlands in the world, and built a quantitative survey and observation system for blue carbon in coastal wetlands based on the integration of vegetation carbon reservoir, soil carbon pool, vertical carbon flux and horizontal carbon flux.
The "fairy circle" formed by the self-organization of the salt marsh wetland ecosystem in Nanhui Beach, Shanghai
In the Yangtze River Delta region, the research team carried out automatic continuous collaborative observation at the Flux Monitoring Tower Station of Chongxi Reed Wetland, Jiudan Sand Reed Wetland, Jiudan Sand Reed Wetland, Jiuduan Sandy Rice Grass Wetland and Dongtou Mangrove Wetland in Chongming Island, Shanghai, and its new solar-induced chlorophyll fluorescence remote sensing, in situ continuous observation and other technologies led the world in accurate estimation of carbon sequestration and key carbon flux research.
Jinshan Parrot Island, which has a salt marsh wetland, is also a research sample site that the scientific research team has been positioning for a long time. Observations show that compared with the natural wetlands in the nearby area, the Cockatoo Island wetland can absorb more carbon dioxide, emit less methane, and have a stronger greenhouse gas emission reduction capacity, which shows that the future wetland restoration project can achieve carbon sequestration and sink increase through technical means, such as changing the hydrodynamic conditions of the wetland.
At present, this team has initiated the establishment of the Blue Carbon Science and Technology Research Center of East China Normal University, extensively united research forces at home and abroad, and formed a global-scale R&D platform integrating production, education and research, carrying out more accurate simulation prediction of the blue carbon function of coastal wetlands in the future, and providing new solutions for the synergy between ecological restoration and carbon sequestration of coastal wetlands.
Column Editor-in-Chief: Xu Ruizhe Text Editor: Xu Ruizhe Title Image Source: Wu Wei Photo
题图说明：崇明东滩湿地水鸟在此过冬。 内图来源：除署名外，均华东师大资料。 Source: Author: Xu Ruizhe