Vertical difference of soil CO2 flux and its driving factors in Loess
Hilly Region, China
Abstract
The diffusion of carbon mineralization in vertical profiles is an
important process of CO2 emission. However, due to the relatively slow
and lagging change of subsoil environment compared with the surface
soil, the process of carbon mineralization and diffusion is often
ignored, and the process and mechanism of deep carbon transfer to the
soil-atmosphere interface are still unclear. we studied the vertical
difference of CO2 flux and its driving mechanism in Robinia pseudoacacia
plantation of different stand ages. The results show that: (1) in the
0-200cm layer, the CO2 flux shows a double peak seasonal trend. Among
them, the total CO2 flux of Robinia pseudoacacia forest in 10 years was
larger. (2) Dynamic evaluation can reduce the uncertainty of static
evaluation, and the contribution of deep CO2 flux to the soil atmosphere
interface is stable, between 21.81-24.42%; (3)Temperature sensitivity
of CO2 flux (expressed as Q10) significantly increases with soil depth,
and the response of water to CO2 flux is different at different section.
There is a significant correlation between the deep CO2 flux and soil
organic carbon (SOC), but there is a reverse feedback effect in the
shallow profile. (4) T & M & C model is more conducive to the accurate
prediction of deep CO2 flux. All in all, this study is of great
significance to the study of the stability of deep soil carbon, the
dynamic change of soil carbon pool and the mechanism of deep carbon
diffusion to the surface in the loess hilly area.