State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 10049, China.
Glob Chang Biol. 2015 Apr;21(4):1567-80. doi: 10.1111/gcb.12797. Epub 2015 Jan 8.
Coastal salt marshes are sensitive to global climate change and may play an important role in mitigating global warming. To evaluate the impacts of Spartina alterniflora invasion on global warming potential (GWP) in Chinese coastal areas, we measured CH4 and N2O fluxes and soil organic carbon sequestration rates along a transect of coastal wetlands in Jiangsu province, China, including open water; bare tidal flat; and invasive S. alterniflora, native Suaeda salsa, and Phragmites australis marshes. Annual CH4 emissions were estimated as 2.81, 4.16, 4.88, 10.79, and 16.98 kg CH4 ha(-1) for open water, bare tidal flat, and P. australis, S. salsa, and S. alterniflora marshes, respectively, indicating that S. alterniflora invasion increased CH4 emissions by 57-505%. In contrast, negative N2O fluxes were found to be significantly and negatively correlated (P < 0.001) with net ecosystem CO2 exchange during the growing season in S. alterniflora and P. australis marshes. Annual N2O emissions were 0.24, 0.38, and 0.56 kg N2O ha(-1) in open water, bare tidal flat and S. salsa marsh, respectively, compared with -0.51 kg N2O ha(-1) for S. alterniflora marsh and -0.25 kg N2O ha(-1) for P. australis marsh. The carbon sequestration rate of S. alterniflora marsh amounted to 3.16 Mg C ha(-1) yr(-1) in the top 100 cm soil profile, a value that was 2.63- to 8.78-fold higher than in native plant marshes. The estimated GWP was 1.78, -0.60, -4.09, and -1.14 Mg CO2 eq ha(-1) yr(-1) in open water, bare tidal flat, P. australis marsh and S. salsa marsh, respectively, but dropped to -11.30 Mg CO2 eq ha(-1) yr(-1) in S. alterniflora marsh. Our results indicate that although S. alterniflora invasion stimulates CH4 emissions, it can efficiently mitigate increases in atmospheric CO2 and N2O along the coast of China.
滨海盐沼对全球气候变化敏感，可能在缓解全球变暖方面发挥重要作用。为评估互花米草入侵对中国沿海地区全球变暖潜势（GWP）的影响，我们沿着江苏省一条沿海湿地的样带测量了 CH4 和 N2O 通量以及土壤有机碳固存速率，样带包括开阔水面、裸露潮滩、入侵的互花米草、本地的盐地碱蓬和芦苇沼泽。每年 CH4 排放量估计为开阔水面、裸露潮滩和 P. australis、S. salsa 和 S. alterniflora 沼泽分别为 2.81、4.16、4.88、10.79 和 16.98 kg CH4 ha(-1)，表明互花米草入侵使 CH4 排放量增加了 57-505%。相比之下，在互花米草和芦苇沼泽的生长季节，负的 N2O 通量与净生态系统 CO2 交换呈显著负相关（P < 0.001）。每年 N2O 排放量分别为开阔水面、裸露潮滩和 S. salsa 沼泽中的 0.24、0.38 和 0.56 kg N2O ha(-1)，而互花米草沼泽为-0.51 kg N2O ha(-1)，芦苇沼泽为-0.25 kg N2O ha(-1)。互花米草沼泽的碳固存率在 100 cm 土壤剖面中达到 3.16 Mg C ha(-1) yr(-1)，是本地植物沼泽的 2.63-8.78 倍。估计的 GWP 分别为开阔水面、裸露潮滩、P. australis 沼泽和 S. salsa 沼泽中的 1.78、-0.60、-4.09 和-1.14 Mg CO2 eq ha(-1) yr(-1)，但在互花米草沼泽中降至-11.30 Mg CO2 eq ha(-1) yr(-1)。我们的结果表明，尽管互花米草入侵刺激了 CH4 排放，但它可以有效地减轻中国沿海地区大气 CO2 和 N2O 的增加。
