Coastal Reclamation and Saltmarsh Carbon Budget: Advances and Prospects |
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| Authors: | Li Jianguo Wang Wenchao Pu Lijie Liu Lili Zhang Zhongqi Li Qiang |
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| Institution: | 1.School of Geography, Geomatics, Planning, Jiangsu Normal University, Xuzhou Jiangsu 221116, China; 2. School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China; 3. The Key Laboratory of the Coastal Zone Exploitation and Protection, Ministry of Land and Resources, Nanjing 210023, China |
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| Abstract: | As an important carbon pool and fragile eco-system of earth system, more and more coastal saltmarshes have been reclaimed for releasing population pressure and promoting food safety and economic development, especially in developing countries. During reclamation, original soil carbon cycling pattern and pathway in saltmarshs would be changed, which furthermore could change global carbon budget. In this study, a great amounts of literature and data were summerized to generalize the changes of soil organic carbon, carbon sequestration rate and carbon flux in three main kinds of saltmarshes (Mangrove saltmarsh, Estuary saltmarsh and coastal saltmarsh) during reclamation. The results are as shown: ①The conclusions collected from Europe and America are not suitable to eastern Asia’s coast and more attention should be paid to eastern Asia’s coastal reclamation; ②Mangrove saltmarshes have higher Soil Organic Carbon (SOC) and carbon sequestration rate, followed by estuary saltmarshes and coastal saltmarshes. Soil clay, aggregate, burial rate usually have positive effect on SOC sequestration in coastal areas. Flood frequency, salinity and underground water level generally have negative effect on it. After reclamation, coastal SOC first shows a decrease followed by an increase. Nearly 30 years of reclamation is the turning point where paddy fields can significantly promote SOC; ③CH4 and CO2 are the main ways of carbon emission in coastal areas of which CO2 flux usually is the largest. Mangrove saltmarshes’ carbon emissions are the highest. In natural sites, the carbon emissions in Spartina alterniflora Loisel. and Phragmites australis are higher than those in bare flat areas. Carbon fluxes in flood tide usually are lower than those in other periods. Otherwise, carbon fluxes in natural saltmarshes are far lower than those in reclamation zones, especially upland tillage zones. The results acquired from field monitoring, saltmarshes are the carbon sinks and become the carbon sources when reclamation activities happen. Finally, three main aspects of coastal study were given as follows: much more attention should be paid to carbon budget inventory in saltmarshes; the effect of reclamation activity (i.e., anthropogenic activity, tillage practice, land use, etc.) on carbon cycling in ocean-inland system; the study of land use and reclamation process simulation and its impact on carbon cycling in coastal zone should be strengthened. |
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| Keywords: | Saltmarsh Reclamation activity Carbon budget |
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