Abstract: Adopting a portable ground penetrating radar (GPR) with 1000 MHz antenna, we detected the root system of Larix gmelinii in two 10 m ×10 m plots at Mao’ershan Experiment Forest Farm, Heilongjiang Province. The GPR detection results were compared with field empirical data, and analyzed the identification rate of GPR techno-logy on different root diameter sizes (0.2-0.5, 0.5-1.0, 1.0-2.0, 2.0-3.0, 3.0-4.0, 4.0-5.0, and >5.0 cm) of L. gmelinii and soil depths (0-10, 10-20, and 20-30 cm). The results showed that for roots with diameter greater than 2.0 cm, the identification rate of 1000 MHz GPR reached 49.8%, with the maximum time interval, total time interval, maximum amplitude area, and total amplitude area of GPR reflection waves being significantly positively correlated with root diameter. For roots with diameter <2.0 cm, the identification rate of GPR was extremely low (6%). As the soil depth increased, root identification rate showed a trend of increasing and then decreasing. The root identification rate was highest at 31.4% in the 10-20 cm soil layer and lowest at 10.2% in the 0-10 cm soil layer. GPR could effectively identify root systems of L. gmelinii with larger diameters (>2.0 cm), and showed an optimal identification rate for root systems in the 10-20 cm soil layer. However, its detection ability for small dia-meter root and deep root of L. gmelinii should be improved.

Key words: ground penetrating radar, root detection, root diameter, identification rate, soil depth