Abstract:

Since fine roots are an important nutrient source and sink in terrestrial ecosystems, fine root mass, the contents of C, N, P and K, as well as their ratios, are crucial information for understanding forest ecosystem nutrient cycling. Biomass, necromass, and C, N, P, K contents in fine roots in the different soil layers were investigated in a broadleaved-Korean pine forest community of the Changbai Mountain during growing season (June to October). Significant seasonal changes in fine root biomass and necromass were observed, with the highest fine root biomass of 6.00 t·hm^-2 occurred in August and the highest necromass of 2.16 t·hm^-2 in September. The K content in live fine roots and N content in dead fine roots also exhibited significantly seasonal changes, with the highest K content of 7.17 mg·g^-1 in September and the highest N content of 14.44 mg·g^-1 in August. The fine root biomass, necromass, and N, K and N:P in live fine roots in 0-10 cm soil layer were higher than those in 10-20 cm soil layer, but the C :N ratio was opposite. There was no significant difference in nutrients of dead fine roots between 0-10 cm and 10-20 cm soil layer. The P and K contents in live fine roots were significantly higher than those in dead fine roots, and the internal cycling rates were 7.26% and 33.11%, respectively. No significant difference in C and N contents was found between live fine roots and dead fine roots.

Key words: broad-leaved Korean pine forest, fine root standing crop, nutrients internal cycling