藏香猪放牧对滇西北高原湿地土壤CO2通量的影响

高原湿地是生态系统中重要的碳汇。土壤CO_2通量作为高原湿地生态系统碳收支的重要组成部分,碳的释放对区域碳平衡发挥着重要的作用。藏香猪放牧是我国高海拔藏区一种特有的放牧方式,是导致高原湿地土壤退化的重要干扰因素之一,并影响着土壤CO_2通量的变化。采用土壤CO_2通量自动测量系统(LI-8100A,LI-COR,USA),分别在不同季节对滇西北布伦、哈木谷、伊拉草原上藏香猪干扰和对照(非干扰土壤)CO_2通量变化进行监测,研究发现,藏香猪干扰型放牧降低了土壤CO_2排放通量,且表现出明显的日波动变化特征。相比旱季,雨季不同放牧方式影响下的土壤CO_2通量差异性更为明显,其中布伦、哈木谷、伊拉草原较对照分别降低了70.4%、87.5%、60.7%。CO_2排放通量与土壤理化性状及植物生物量的回归分析表明,对照样地的土壤容重、孔隙度、pH、总活性碳、植物生物量与土壤CO_2通量具有显著的相关性(P0.01)。通过植物-土壤指数(plant-soil index,PSI)分析了藏香猪干扰型放牧对高原湿地的影响,总体来看,对照样地中土壤CO_2通量与PSI之间具有较好的线性关系,可以用来很好的预测未来高原湿地土壤CO_2通量的变化。该研究结果不仅有效估算了强干扰放牧影响下的高原湿地土壤碳排放量,而且为加强藏香猪放牧的科学管理,高原湿地生态系统的保护、恢复及重建提供了理论支持。

Effects of Tibetan pig herding on soil CO2 fluxes in a plateau wetland of northwestern Yunnan, China

Plateau wetlands are important carbon sinks in ecosystems. As an important part of the carbon budget of the plateau wetland ecosystem, soil CO₂ fluxes play an important role in the regional carbon balance. Tibetan pig herding is a unique grazing method in high-altitude Tibetan areas of China. It is an important disturbance factor that causes soil degradation in plateau wetlands and affects the change of soil CO₂ fluxes. A soil CO₂ fluxes automatic measurement system (LI-8100A, LI-COR, USA) was used to detect CO₂ fluxes from the disturbance of Tibetan pig herding and the control (without Tibetan pig herding) in the Bulun, Hamugu, and Yila grasslands in northwestern Yunnan during different seasons. We found that Tibetan pig herding reduced the CO₂ fluxes of the soil and there were clear daily fluctuations. Compared with the dry season, the effects of different grazing methods on CO₂ fluxes were more obvious during the rainy season, with values of 70.4%, 87.5%, and 60.7% for the Bulun, Hamugu, and Yila grasslands, respectively. The correlation of CO₂ fluxes with the physical and chemical properties of the soil and plant biomass indicated that there was a significant correlation between soil bulk density, porosity, pH, total labile carbon, plant biomass, and soil CO₂ fluxes during the control plots. The impact of grazing on the plateau wetland was analyzed by a plant-soil index (PSI). Overall, there was a good linear relationship between soil CO₂ fluxes and PSI in the control plots. This index could be used to predict future changes in soil CO₂ fluxes in plateau wetlands. The results of this study not only effectively estimate soil carbon emissions of a plateau wetland under the influence of a strong grazing disturbance, but also provide theoretical support for strengthening the scientific management of Tibetan pig herding and the protection, restoration, and reconstruction of plateau wetland ecosystems.