摘要
为了揭示冬季滨海湿地植被收割对其沉积物中温室气体释放的影响,以长江入海口典型滨海湿地——崇明东滩为研究对象,观测季节性（冬季）植被收割（分别于收割后第0天、第10天、第30天、第60天采样）与不收割条件下芦苇（Phragmites australis）、米草（Spartina alterniflora）、芦苇-米草交互带和光滩沉积物中CO2与N2O的释放特征.结果表明：1米草和芦苇-米草交互带植被收割并未增加沉积物中CO2的释放（P〈0.05）,但芦苇收割可能会增加N2O的释放（P〈0.05）,说明植被收割对湿地沉积物中CO2和N2O释放的影响与植被类型密切相关.2与芦苇带相比,米草和芦苇-米草交互带沉积物中CO2累积释放量分别高出12%-57%和17%-43%,但芦苇植被覆盖下沉积物中N2O累积释放量分别比二者高出11%-81%和8%-95%.可见,米草和芦苇-米草交互带沉积物碳的呼吸损失明显高于芦苇带,但芦苇植被覆盖下沉积物中N2O逸失量相对较高.34种植被类型下,沉积物中N2O累积释放量为0.1-0.4 mg/kg,CO2累积释放量则高达1024-2645 mg/kg.因此,冬季滨海湿地植被收割不会显著增加N2O的温室效应,但选择性收割米草有望减少沉积物碳的呼吸损失.
Vegetation harvest in winter from coastal wetlands has become increasingly popular in eastern China,because of the need for eutrophication control and the fact that the plant can be freely used as papermaking raw materials. However,insufficient investigation has been conducted to evaluate the effects of the disturbance on emissions of greenhouse gases in sediments. Field plot experiments were arranged in vegetation zones of Phragmites australis,Spartina alterniflora,the intergrowth area of the two species and mudflat in a typical coastal wetland,Chongming Dongtan,in the Yangtze River Delta of China. Each plot was treated as half-and-half into two subplots,managing with and without vegetation harvest in winter. Sediment samples were taken from all subplots at 0,10,30,and 60 days after harvesting. The sediment cores were incubated at 30 ℃ for 60 days,measuring CO2 and N2O fluxes over time to determine whether the seasonal vegetation harvest substantially affected emissions of the two greenhouse gases in sediments or not. The results showed that harvesting vegetation from the S. alterniflora zone and the intergrowth area of P. australis and S. alterniflora did not enhance CO2 emissions in sediments,while harvesting P. australis possibly enhanced N2 O emissions（ P〈0. 05）. This indicated that the effects of vegetation harvest on CO2 and N2O emissions in the sediments largely depended on vegetation types. The total effluxes of CO2 in the S. alterniflora zone and the intergrowth areas were12%-57% and 17%-43% higher than those in the P. australis zone,respectively. However,N2 O emissions in the P. australis zone were 11%-81% and 8%-95% higher than those in the S.alterniflora zone and the intergrowth areas, respectively. Thissuggested that respiration losses of carbon in sediments in the S. alterniflora zone and the intergrowth areas were found to be much higher than those in the P. australis zone. In contrast,N2 O emissions in the P. australis zone were clearly greater than those in the S.alterniflora zone and the intergrowth areas. In addition,the total amounts of N2 O emissions across the four zones were 0. 1-0. 4 mg/kg in the 60-day incubation,while the emissions of CO2 reached up to 1024-2645 mg/kg. Therefore,seasonal vegetation harvest in the coastal wetlands hardly increases the contribution of N2 O to the greenhouse effect. Selectively harvesting S. alterniflora potentially reduces the respiration loss of carbon in sediments. This implies that the short-term vegetation harvest in coastal wetlands is environmentally costeffective.
出处
《环境科学研究》
EI
CAS
CSSCI
CSCD
北大核心
2015年第8期1200-1208,共9页
Research of Environmental Sciences
基金
国家自然科学基金项目(41375149)
江苏高校优势学科建设工程资助项目(PAPD)
