外源碳输入对华北平原农田和湿地土壤有机碳矿化及其温度敏感性的影响

Effects of exogenous carbon input on soil organic carbon mineralization and temperature sensitivity of cropland and wetland in the North China Plain

研究外源碳输入和气候变暖对土壤有机碳矿化的影响,对于深入理解土壤有机碳的稳定和积累机制以及其对全球变化的响应具有重要意义。通过为期35 d的室内培养试验,利用^13C稳定同位素标记技术,研究了华北平原典型农田和湿地土壤在15℃和25℃下的土壤有机碳矿化及激发效应。结果表明,土地利用类型(农田/湿地)、温度(15℃/25℃)和葡萄糖添加[0.4 mg(C)·g^-1]对土壤有机碳矿化均具有显著影响。在相同培养温度下,未添加葡萄糖的农田和湿地土壤有机碳矿化无显著差异,而添加葡萄糖处理下农田土壤有机碳矿化显著高于湿地土壤。除湿地土壤在15℃下培养外,添加葡萄糖显著促进了农田和湿地土壤有机碳矿化,农田土壤有机碳矿化的激发效应显著高于湿地土壤。温度升高显著促进了农田和湿地土壤有机碳矿化,培养过程中土壤有机碳矿化温度敏感性Q10为1.2~1.6,土地利用类型和葡萄糖添加对土壤有机碳矿化温度敏感性的影响都不显著。在温度升高和外源碳输入的共同作用下,农田土壤有机碳矿化显著高于湿地土壤。

The influences of exogenous carbon input and climate warming are two key factors of soil organic carbon mineralization.Based on a 13C stable isotope labelling technique,we conducted a laboratory incubation experiment to investigate the priming effect and temperature sensitivity of soil organic carbon mineralization of cropland and wetland in the North China Plain to understand and forecast soil carbon dynamics under global climatic change.Topsoil collected from cropland and wetland of Hengshui region were incubated with or without 13C-labeled glucose[0.4 mg(C)·g^-1]at two temperature(15℃and 25℃)for 35 days.Soil CO2 emission and its^13C isotopic composition was measured at days 1,3,5,7,10,14,21,28 and 35.Our results suggested that the soil organic carbon mineralization was significantly influenced by land use type,temperature,and glucose addition.The soil organic carbon mineralization of the cropland was approximately equal to that of the wetland without glucose addition but it was significantly higher than that of wetland with glucose addition at the same temperature.Except the wetland soil cultured at 15℃,glucose addition exerted a significantly positive priming effect on soil organic carbon mineralization in wetland and cropland soil.However,the priming effect of the cropland was significantly higher than that of wetland.Soil organic carbon mineralization was also accelerated by increased temperature,and the Q10 value of its temperature sensitivity fluctuated between 1.2 and 1.6 during incubation.The temperature sensitivities of soil organic carbon mineralization were not significantly changed by different land use types and glucose addition.In conclusion,the soil organic carbon mineralization of the cropland was significantly higher than that of wetland under warming conditions and exogenous carbon input.