藏东南色季拉山不同海拔森林土壤基础呼吸特征

为阐明不同海拔高度森林土壤基础呼吸对温度变化的响应,为未来气候变化情景下不同海拔高度土壤碳动态预测提供科学依据,以藏东南色季拉山不同海拔高度森林表层土壤为研究对象,通过室内升温实验,研究不同海拔高度森林表层土壤基础呼吸对温度变化的响应。结果表明,土壤基础呼吸速率及土壤累积碳通量均随培养温度的升高呈增加趋势,土壤基础呼吸速率随着土壤层次加深而降低。随着培养时间延长,各土壤层次及海拔高度土壤基础呼吸速率总体呈先增加后降低的趋势,局部表现为振荡变化的特征,二者之间呈极显著(P<0.01)负相关指数函数关系。随着培养时间延长,土壤基础呼吸累积碳通量呈增加趋势,且培养的前14 d土壤累积碳通量增幅明显,之后逐渐趋于稳定。土壤基础呼吸累积碳通量与培养时间呈极显著(P<0.01)正相关对数函数关系。总体来看,温度升高将加速森林生态系统表层土壤呼吸碳排放。

Characteristics of soil basic respiration in different altitude forests in Sejila Mountain,southeast of Tibet

In order to clarify the responses of soil basal respiration to temperature changes at different altitudes, and to provide scientific basis for predicting soil carbon dynamics at different altitudes in the future climate change scenarios, the forest soils at different altitudes in Sejila Mountain were studied by laboratory simulated heating experiment. It was shown that soil basal respiration rate and soil accumulated carbon flux increased with the increase of temperature. With the deepening of the soil layer, soil basal respiration rate was decreased. Soil respiration rate of all layers and altitudes increased at first and then decreased with the extension of simulated culture time, while local parts showed a characteristic of concussion change. There was a significant (P<0.01) negative correlation between soil basal respiration rate and culture time, which could be described as exponential function. The cumulative carbon flux of soil basal respiration showed an increasing trend with the prolongation of culture time, and the increases of soil accumulated carbon flux were obvious in the first 14 days, and then gradually became stable. There was a significant (P<0.01) positive correlation between accumulated soil carbon flux and incubation time, which could be described as logarithmic function. In summary, elevated temperature would accelerate carbon emission via surface soil respiration of forest ecosystem.