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采用4个梯度的林地氮处理(N_0、N_3、N_6和N_9依次为0、3、6和9 g N·m-2·a-1),利用分解袋试验,研究了N添加对油松不同径级细根分解及养分释放过程的影响.结果表明:细根分解过程分为快速分解(0~60 d)和慢速分解(60~300 d)两个阶段.0~0.4、0.4~1和1~2mm细根分解的质量百分数在第60天分别为7.6%、10.4%和11.4%,在第300天分别为19.8%、23.5%和30.5%,说明较细的根系分解较慢.N添加显著降低了0~0.4 mm细根的分解速率,但对0.4~1和1~2 mm细根分解速率无显著影响,与对照(N0)相比,N3、N6和N9处理试验期间分解速率分别降低2.1%、4.5%和5.8%.N添加显著增加了0~0.4和0.4~1 mm细根C和N残留率,但对1~2 mm细根C和N残留率无显著影响,且对3个径级细根P残留率无显著影响.与对照相比,N3、N6和N9处理分别增加了0~0.4 mm细根中8.1%、9.4%和4.5%的C残留率和5.3%、16.3%和16.7%的N残留率;同时增加了0.4~1 mm细根中2.5%、2.5%和0.9%的C残留率和0.9%、2.3%和3.9%的N残留率.0~0.4、0.4~1 mm细根C、N、P迁移模式总体表现为直接释放,而1~2 mm细根N为富集-释放模式.氮沉降可能主要通过影响0~0.4mm细根(主要为1和2级细根)的分解过程,从而降低细根的分解速率.
Using four gradient nitrogen treatments (N_0, N_3, N_6 and N_9 followed by 0, 3, 6 and 9 g N · m-2 · a-1) Diameter fine root decomposition and nutrient release process.The results showed that the fine root decomposition process was divided into two stages: rapid decomposition (0 ~ 60 d) and slow decomposition (60 ~ 300 d) .0 ~ 0.4 and 0.4 ~ 1 And 1 ~ 2mm mass fraction of fine root decomposition were 7.6%, 10.4% and 11.4% on the 60th day and 19.8%, 23.5% and 30.5% respectively on the 300th day, which indicated that the fine root decomposed slowly. The additions significantly reduced the decomposition rate of fine roots from 0 to 0.4 mm, but had no significant effect on the fine root decomposition rates from 0.4 to 1 and 1 to 2 mm. Compared with the control (N0), the decomposition rates during N3, N6 and N9 treatments Respectively, decreased by 2.1%, 4.5% and 5.8% respectively.N addition increased the residual C and N contents of fine roots of 0 ~ 0.4 and 0.4 ~ 1 mm, but had no significant effect on residual C and N of fine roots of 1 ~ 2 mm Had no significant effect on the residual rate of fine root P in three diameter classes.Compared with the control, N3, N6 and N9 treatments increased the C residual rates of 8.1%, 9.4% and 4.5% in fine roots of 0 ~ 0.4 mm and 5.3% , 16.3% and 16.7% of the N residual rate; while an increase of 0.4 ~ 1 mm fine roots 2.5%, 2.5% and 0.9% C residual rate and N residual rate of 0.9%, 2.3% and 3.9% .The migration patterns of fine roots C, N and P of 0 ~ 0.4 and 0.4 ~ 1 mm showed the direct release as a whole, while fine root N of 1 ~ 2 mm was rich Set-release model. Nitrogen deposition may reduce the decomposition rate of fine roots mainly by affecting the decomposition process of 0-0.4 mm fine roots (mainly fine roots 1 and 2).