Environmental controls and influences of Pinus roxburghii Sarg. (Chir pine) plantation on temporal variation in soil carbon dioxide emission and soil organic carbon stock under humid subtropical region.

Soil carbon dioxide emission is a major component of ecosystem respiration, responsible for organic carbon losses from the ecosystem. In Pinus roxburghii Sarg. plantations, higher CO ₂ emission coincided with maximum soil moisture and soil temperature during the rainy season (4.23 µmol CO ₂ m ^-2  s ^-1 ) followed by summer season (1.69 µmol CO ₂ m ^-2  s ^-1 ) and winter season (1.35 µmol CO ₂ m ^-2  s ^-1 ). The soil CO ₂ emission rates recorded during the rainy season differed significantly from other seasons (p < 0.05). Multiple linear regression revealed that rainfall was the main dominant factor affecting the soil CO ₂ emission. A significant positive correlation with minimum air temperature and average air temperature during the lag period, i.e., preceding 15 days of data, was recorded. A significant positive correlation was also observed between annual soil CO ₂ emission rates with soil temperature, soil moisture, air temperature, and rainfall (p < 0.05). Vapor pressure and relative humidity at 14.19 h also emerged as additional scientific variables affecting soil CO ₂ emission with significant positive correlations. Annual soil CO ₂ emission rates and soil properties were not significantly correlated but were positively correlated with organic carbon, exchangeable potassium and negatively correlated with available nitrogen and phosphorous (p > 0.05). Higher annual average carbon stock, 95.05 t ha ^-1 in P. roxburghii plantations than the yearly soil CO ₂ emission, 33.23 t ha ^-1 indicates that plantations sequester more carbon than the emissions.
(© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)