Assessment of Soil Carbon Dioxide Efflux and its Controlling Factors in Moist Temperate Forest of West Himalayas

In this study, the soil CO₂ efflux was measured by closed dynamic system method along with soil and meteorological parameters at 1600, 1700 and 1800 m elevations along different directional-aspects over a period of one year. The annual CO₂ efflux rate (F_c) varied from 1.02 to 22.57 μmol m^–2 sec^–1, which was highest in the rainy season. The annual average F_c was maximum (8.67 μmol m^–2 sec^–1) at east facing slope followed by 7.58 and 7.32 μmol m^–2 sec^–1 at south facing slope and north facing slope respectively. Temperature (T_s), moisture (S_m) and evaporation of soil were found to be significant variables and selected to develop the regression model with R² value of 0.85. The effect of soil moisture on F_c above 15°C T_s exhibited a better relationship with R² value of 0.48 and temperature sensitivity (Q10) was found 3.25. This study reveals that the key controlling factors of CO₂ efflux rate are soil moisture and soil temperature, which explains 66% variation in soil CO₂ efflux.