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 1～2
mm 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(N 0 )相比，N 3 、N 6 和 N 9 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，N 3 、N 6 和 N 9 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 0～0．4
mm 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．
其他摘要
We examined the effects of four nitrogen (N) addition treatments，i．e．，N 0 (0 g N·m
－2
a
－1
)，N 3 (3 g N·m
－2
a
－1
)，N 6 (6 g N·m
－2
a
－1
) and N 9 (9 g N·m
－2
a
－1
) on the decomposition
and nutrient release processes of fine roots with different diameters in Pinus tabuliformis plantation
using litterbag method． The results showed that the decomposition process of fine roots could be di-
vided into rapid (0－60 d) and slow (60－300 d) decomposition stages． The decomposition mass
percentages of fine roots with 0－0．4 mm，0．4－1 mm and 1－2 mm were 7．6%，10．4% and 11．4%
on the 60th day and 19．8%，23．5% and 30．5% on the 300th day，respectively，indicating that fi-
ner root had lower decomposition rates． N addition reduced significantly the decomposition rates of
fine roots with 0－0．4 mm diameter，but had no significant influence on those of root with 0．4－1 mm
and 1－2 mm diameters． Compared with the control，N 3 ，N 6 and N 9 treatments reduced the decom-
position rates by 2．1%，4．5% and 5．8%，respectively． N addition increased both the C and N re-
maining percentages of fine roots with 0－0．4 mm and 0．4－1 mm diameters，but had no significant
influence on those with 1－2 mm diameters． Additionally，P remaining percentages of fine roots had
no response to the N addition． Compared with the control，N 3 ，N 6 and N 9 treatments increased the
root C remaining percentages by 8．1%，9．4% and 4．5% in 0－0．4 mm diameter roots，and 2．5%， 2．5% and 0．9% in 0．4－1 mm diameter roots，respectively． Similarly，N 3 ，N 6 and N 9 treatments al-
so increased the root N remaining percentages by 5．3%，16．3% and 16．7% in 0－0．4 mm diameter
roots and 0．9%，2．3% and 3．9% in 0．4－1 mm diameter roots，respectively． The transfer models for
C，N and P in 0－0．4 mm and 0．4－1 mm diameters were direct releasing，and the transfer models
for N showed an enriching-releasing model． N deposition may decrease the fine root decomposition
rates mainly by affecting the decomposition process of fine roots with 0－0．4 mm diameters (mainly
the first two order roots)．
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