Priming Effect of Coupling Function of Exogenous Organic Matter and Temperature on Soil Organic Carbon of Pinus koraiensis Broad-leaved Mixed Forest

Objective The effect of the addition of different proportion of exogenous organic matter on the forest soil organic carbon mineralization was discussed in this study in order to further understand the ecological relationship between the added exogenous organic matter and soil organic carbon.

Method The dead leaves of Korean pine (Pinus koraiensis) and other broad-leaved species (e.g. Linden and maple) were collected in Korean pine broad-leaved mixed forest experimental plots in Liangshui National Nature Reserve and regarded as exogenous organic matter. The mineralization process was imitated in the incubators through laboratory incubation method by adding different proportions of Korean pine dead leaves and broad dead leaves at different incubation temperature (25 ℃, 30 ℃, and 35 ℃) and incubation days (5 d, 10 d, 20 d, 35 d, 60 d, and 90 d). The soil CO₂ released under different treatments was measured by alkali absorption method, and the mineralization rate and cumulative mineralization amount of soil organic carbon were calculated. And then the priming effect of exogenous organic matters and temperature on soil organic carbon was analyzed.

Result At the incubation temperatures of 25 ℃ and 35 ℃, the priming effect of dead broad leaves was better than that of dead Korean pine leaves; while at 30 ℃, the result was opposite. Under the three levels of incubation temperature, the addition of dead leaves produced a significant promoting effect on soil mineralization processes (P < 0.05). At the temperature of 30 ℃, the addition of the exogenous organic matter resulted in the strongest priming effect on the soil organic carbon.

Conclusion The priming effect of soil organic carbon in Korean pine broad-leaved mixed forest was influenced by multi-factors, such as the types of added exogenous organic matter, incubation temperature and days.