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, F, 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.
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