Responses Of Soil Respiration To Different Disturbance In A Typical Grassland In Northern China

Research on the effects of soil CO₂release rate from soils subject to differentdisturbance, is meaningful for a better understanding of soil CO₂release mechanism andestimation of CO₂emissions under different land use. The present work on the nationalgrassland ecosystem field station in Hebei Guyuan, was conducted from2011June to2012October. There were4disturbance treatmentsBurnt,, mown, irrigated, fertilized,. Soil surveys measured soil CO₂release rate andsurface temperature and moisture changes. The diurnal and seasonal variation of soil CO₂release rate, and difference of soil CO₂release rate among different disturbance wereanalyzed.,The main results are as follows:Periodic change of diurnal variation of soil temperature and soil CO₂release rate issimilar, the maximum value of soil CO₂emission rate appeared in the14:00-16:00; and thehighest values of the soil temperature at10cm appeared in the16:00; the lowest value of soilCO₂emission rate appeared in0:00-3:00, the lowest value for CO₂release was about3hourslater. Due to the combined effects of temperature and plant growth, amplitude of soil CO₂summer release rate is greater than the spring and autumn. Among different land use types,there were no significant differences in diurnal variation of soil CO₂release rate.Comparison between the average value and8:00-10:00value of soil CO₂emission rateindicated that soil CO₂release rate in8:00-10:00can represent the daily average value.Under different disturbance of soil CO₂release rate showed a seasonal variationcharacteristic of high rate in summer and low rate in spring and autumn. The change processof soil CO₂release rate in the intraseasonal influenced by crop growth, soil temperature andsoil moisture change; soil CO₂emission rates increased exponentially with soil temperature,and in the low temperature was good. There were significant differences of soil heterotrophicrespiration under different disturbance fertilization, mowing,and burning had the greatestimpact. The ratio of total respiration to soil heterotrophic respiration rate were significantlylower under these disturbance regimes...