Time lag between soil respiration and soil temperature in a Robinia pseudoacacia plantation in the south of the Taihang Mountains

ObjectiveSoil respiration is one of main components in carbon cycle of the terrestrial ecosystems. In this study, the difference of temperature sensitivity coefficient (Q₁₀) between soil respiration of Robinia pseudoacacia plantation and soil temperature of each soil layer was examined and the time lag between soil respiration and soil temperature of each soil layer was investigated on annual scale and daily scale.

MethodSoil respiration was measured using an automatic positioning observation system Li-8150 in the 50-year-old Robinia pseudoacacia plantation in the south of the Taihang Mountains.

Resulton the annual scale, soil respiration of Robinia pseudoacacia plantation and the temperature of each soil layer had no time lag and showed a significant exponential relationship (P < 0.001) so that their phase need not be calibrated. Q₁₀ varied from 2.23 to 2.53, increased slightly with the measurement depth of soil temperature and the correlation coefficient (R²) of the exponential model decreased slightly with the measurement depth of soil temperature. On the daily scale, soil respiration and the temperature of each soil layer had a time lag with small R² and inaccurate Q₁₀. Soil respiration and temperature of each soil layer need to be calibrated in phase to obtain a better R² and more accurate Q₁₀. Q₁₀ increased with the measurement depth of soil temperature after the phase was calibrated, but Q₁₀ measured in subsoil (> 20 cm) was too large for biological characteristics. The increase of Q₁₀ with soil depth was related with the temperature amplitude of soil layer at the surface layer (< 20 cm).

ConclusionOn the annual scale, the difference of the Q₁₀ value of each soil layer was not evident, which can reflect the relationship between soil respiration of Robinia pseudoacacia plantation and temperature. On a daily scale, surface Q₁₀ is recommended to reflect the relationship between soil respiration of Robinia pseudoacacia plantation and soil temperature.