中文摘要：

细根（直径≤2mm）是植物吸收水分和养分的重要器官,细根通过呼吸作用和周转过程向土壤输送有机质（Jackson et al.,1997;王政权等,2008）。细根生物量虽然仅占植物体总生物量的5%左右,但由于细根生长和周转迅速,其生长量可占森林初级生产力的50%～75%（Nadelhoffer et al.,1992）,每

英文摘要：

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, neeromass, 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.hm2 occurred in August and the highest necromass of 2. 16 t.hm2 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＇g1 in September and the highest N content of 14.44 mg.g 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.