Abstract: As a functional organ of plant, fine root is an important channel for nutrient transmission between plant and soil. Prescribed burning is an important way of forest management. Studies on the impacts of fire on fine root biomass will help understand the composition of plant communities and the underground competition. In early November 2018, a prescribed burning experiment was conducted in a Korean pine (Pinus koraiensis) plantation in Hegang. Fine root and soil samples were collected at 0-10 cm and 10-20 cm layers using a soil corer with an inner diameter of 7 cm. We measured the composition of fine root biomass, and analyzed the changes in soil properties after the prescribed burning and the main factors affecting fine root biomass. The results showed that the biomass of living fine roots at 0-10 cm and 10-20 cm layers significantly decreased by 5.7%-16.3% and 6.1%-12.4% after the prescribed burning, respectively, and the biomass of dead fine roots at 0-10 cm and 10-20 cm layers significantly increased by 8.5%-17.4% and 5.1%-14.1%, respectively. After the prescribed burning, the biomass of fine roots of trees at 0-10 cm and 10-20 cm layers was significantly reduced by 17% and 10% respectively, and the biomass of fine roots of herbs at 0-10 cm and 10-20 cm layers was significantly increased by 14% and 9%, respectively. In addition, prescribed burning significantly increased the ratios of absorptive root biomass to transport root biomass at 0-10 cm and 10-20 cm layers by 5.7%-12.9% and 4.2% respectively, and the proportion of absorptive root biomass in fine root biomass. Fine root biomass had different responses to soil factors before and after the prescribed burning. According to RDA analysis, the biomass of fine roots after prescribed burning was mainly affected by soil temperature, water content, and ammonium nitrogen content. Rising temperature promoted the growth of fine root biomass. The biomass of absorptive roots of trees and herbs was significantly positively correlated with soil moisture, and the biomass of absorptive roots of trees was positively correlated with soil ammonium nitrogen content. In conclusion, fine root biomass of Korean pine plantation responds to prescribed burning in plant life-forms, fine root functional types and soil influencing factors. This study revealed the effects of prescribed burning on fine root biomass of Korean pine plantation, providing theoretical support for rational prescribed burning.

Key words: prescribed burning, fine root biomass, soil physical and chemical properties, functional type, influencing factor