Key message

During the non-growing season, environmental factors changed after fire, leading to significantly increased non-growing season soil heterotrophic respiration (R_h) and potentially decreasing the amount of net C stored in cold temperate forest ecosystems of China.

Context

Intensifying forest fire regimes are likely to influence future C budgets of forest ecosystems. However, the mechanism of fire disturbance on the components of non-growing season soil respiration rate (R_s) and its environmental factors are not fully understood, creating uncertainties for future C sink estimates under climate change scenarios.

Aims

This study examined the effects of recent fire on non-growing season (November 2017 to April 2018) R_s, its heterotrophic (R_h) and autotrophic (R_a) components, and Q₁₀ in a cold temperate forest in northeast China.

Methods

Soil CO₂ effluxes (including R_h and R_a) were measured using an Li-8100 portable automatic measuring system for soil C flux (Li-Cor, Inc.; Lincoln, NE, USA). Soil temperature and moisture were measured using a temperature probe (Licor p/n8100–201) and soil volumetric water content probe (ECH20 167 EC-5; p/n 8,100,202), respectively, at a depth of 5 cm; snowpack depth was measured with a ruler.

Results

During the non-growing season, fire significantly increased the R_h by approximately 47% in burned stands. The Q₁₀ of R_h significantly increased from 2.39 in the unburned stands to 3.12 in the burned stands. An interaction between soil temperature and snowpack depth was the driving environmental factor controlling the non-growing season soil respiration and its components after fire disturbance.

Conclusion

Fire is a potent factor on the components of the soil respiration and should not be ignored in forest ecosystem C cycling, especially during the non-growing season as it is vulnerable to micro-environmental variation. Long-term studies involving diverse ecosystems are required to better elucidate mechanisms that have been found during the non-growing season R_s under an increasing trend of fire occurrence.