Global warming is well-known, which is mainly because of the increase of greenhouse gas in the atmosphere, such as carbon dioxide (CO2) and methane (CH4). Natural peatland as a sink of atmospheric CO2 and a source of atmospheric CH4, plays an important role in global carbon cycle. However, grazing could affect the emissions of the CO2 and CH4 fluxes in the peatland. So far, many studies focused on the influences of grazing on the emissions of both CO2 and CH4 fluxes in the wetlands and there are still no consensus achieved. In this study, to understand the influence of grazing on the emissions of both CO2 and CH4 fluxes in wetland, we investigated the emissions of both CO2 and CH4 fluxes from the fencing and grazing sites in the Zoige Plateau wetland, which is the highest Plateau wetland in the world. The CO2 and CH4 fluxes were measured based on the dark static chamber method using the Fast Greenhouse Gas Analyzer over the growing season in 2013. Results showed that the aboveground biomass in the grazing site decreased by 350.21 g·m-2 compared with the fencing site, while belowground biomass in the grazing site increased by 729.17 g·m-2 compared with the fencing site. The mean CO2 emissions over the growing season in the fencing and grazing sites were (845.02±559.24) (standard deviation) mg·m-2·h-1 and (763.78±534.99) mg·m-2·h-1 with no significant difference. In addition, the mean CH4 emissions in the fencing and grazing sites were (7.65±5.92) mg·m-2·h-1 and (7.91±4.94) mg·m-2·h-1 with no significant difference. However, the mean CH4 emission during the main grazing period (from late July to September in 2013) in the grazing site significantly increased by 54.3% compared with the fencing site. During the main grazing period, the enhanced CH4 emissions in grazing site mainly relied on vascular plants transport in the low water table, the high methanogenic activity at the high soil temperature, and the large plant biomass. Therefore, the results will help to provide basic information for the reasonable wetland management and mitigating the emissions of greenhouse gas.%全球气候变暖已是不争的事实，主要是由于大气中CO2和CH4浓度的大幅度增加。泥炭地作为大气CO2“汇”和CH4排放“源”，在全球碳循环中发挥着重要的作用。然而，放牧管理影响着泥炭地CO2和CH4排放通量，以前有关放牧管理对湿地 CO2和 CH4排放通量的影响研究仍未取得一致的结论。选择了世界上最高的湿地若尔盖高原湿地作为研究样点，对比研究了若尔盖高原湿地围栏内和放牧地 CO2和 CH4的排放，有助于深刻理解放牧管理对 CO2和 CH4排放通量的影响过程。于是，在2013年6─10月，基于静态暗箱法，CO2和CH4通量测量采用快速温室气体分析仪（DLT-100，Los Gatos Research， USA）。结果表明：放牧地地表植物生物量较围封地减少了350.21 g·m-2，但增加了地下植物根的生物量729.17 g·m-2。生长季期间，围封地和放牧地的CO2排放通量平均值（±标准差）为(845.02±559.24)和(763.78±534.99) mg·m-2·h-1，但它们无差异显著；而CH4排放通量为(7.65±5.92)和(7.91±4.94) mg·m-2·h-1，它们之间也无差异显著。然而，集中放牧期间（7月下旬至9月底），放牧地CH4排放通量较围封地增加了54.3%，这种CH4排放通量增加的结果主要出现在水位趋向下降，温度最高和生物量最大的条件下，并且 CH4排放以维管植物传输方式为主的时期。因此，这些结果有助于为湿地合理经营和减缓温室气体排放提供数据支撑。
展开▼
