TITLE:
Seasonal Change in CO2 Production Rate along Depth in a Grassland Field
AUTHORS:
Ippei Iiyama
KEYWORDS:
Gas Diffusion Coefficient, Mass Balance Equation, Soil Temperature, Volcanic Ash Soil, Water Content
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.11 No.6,
June
28,
2023
ABSTRACT: Soil is a large terrestrial carbon pool so that the evaluation and
prediction of soil respiration is important for understanding and managing
carbon cycling between the pedosphere and the atmosphere. For better
understanding about characteristics and mechanisms of soil respiration, this
study monitored seasonal behaviors of soil gaseous CO2 concentration
profile with relevant soil physical conditions in a meadow field, and
numerically analyzed the monitored data sets to inversely determine time-series
of depth distributions of CO2 production rate in the field by
assuming optimum ranges of depth and moisture condition for aerobic respiration
of soil fauna and flora. The results of the inverse analyses showed that the
depth range of intense CO2 production resided in top soil layers
during summer and moved down into subsoil layers in winter, implying that the depth
range of main CO2 sources can change dynamically with seasons. The
surface CO2 emission rates derived from the inverse analyses fell in
the range typically found in the same kind of land use. The evaluated mean
residence time of gaseous CO2 in the study field was around
half a day. These findings suggested that the modelling assumptions about soil
respiration in this study are effective to probe spatial and temporal behavior of respiratory activity
in a soil layer, and it is still important to integrate facts about in-situ CO2 concentration
profiles with soil physical parameters for quantitatively predicting possible
behaviors of soil respiration in response to hypothetical changes in
atmospheric and soil climates.