滨海沼泽湿地转化为养殖塘对其碳储量的影响

以闽江河口为研究区域,配对采集芦苇(Phragmites australis)湿地、短叶茳芏(Cyperus malaccensis)湿地和互花米草(Spartina alterniflora)湿地的植物、土壤(0~100cm)及由其围垦而成的水产养殖塘沉积物(0~100cm)样品,测定其有机碳含量,计算生态系统碳储量,并估算沼泽湿地围垦造成的碳释放量.结果表明,闽江河口芦苇湿地、短叶茳芏湿地、互花米草湿地生态系统碳储量分别为(152.85±8.88),(151.63±6.33),(155.85±10.82)Mg C/hm²,其转化成的养殖塘沉积物碳储量分别为(112.69±4.26),(128.24±15.81),(118.59±8.26)Mg C/hm²,转化后生态系统碳储量分别下降26.3%、15.4%和23.9%,引发的碳排放分别为(145.49±33.00),(120.66±26.49),(136.76±27.61)Mg CO₂-eq/hm².上述生态系统碳储量下降的64%来自植物碳库的损失,36%来自土壤碳库的减少.滨海沼泽湿地围垦为养殖塘明显降低滨海湿地碳储量,因此,退塘还湿生态恢复可对滨海湿地固碳增汇起到重要作用.

Effect of conversion of coastal marsh into aquaculture ponds on ecosystem carbon stocks in the Min River estuary

In order to scientifically assess the impact of land use/land cover changes on blue carbon pool of coastal tidal marsh, it is valuable to determine the changes of ecosystem carbon stock following conversion of coastal marsh to aquaculture ponds. In the Minjiang River estuary zone, we collected the samples of the aboveground and belowground plants, and the soils (0~100cm) from the Phragmites australis, Cyperus malatensis and Spartina alterniflora marshes, and the top 100cm sediment of the aquaculture ponds reclaimed from above three different marshes. The organic carbon content of plants, and soil / sediment samples were measured. The blue carbon storage of P.australis marsh ecosystem, C.malaccensis marsh ecosystem and S.alterniflora marsh ecosystem was (152.85±8.88), (151.63±6.33), and (155.85±10.82)Mg C/hm², respectively, and the sediment carbon storage of the aquaculture ponds was (112.69±4.26),(128.24±15.81), and (118.59±8.26)Mg C/hm², respectively. The blue carbon storage of P.australis marsh ecosystem, C.malaccensis marsh ecosystem and S.alterniflora marsh ecosystem decreased by 26.3%, 15.4%, and 23.9%, respectively, resulting in (145.49±33.00), (120.66±26.49), and (136.76±27.61)Mg CO₂-eq/hm² carbon emissions. Our results showed that conversion of coastal marsh into aquaculture ponds greatly decreased ecosystem carbon storage. We suggested that ecological restoration of aquaculture pond into marsh ecosystem will play an important role in coastal wetland carbon sequestration.