水保所知识产出(1956---)知识库

氮(N)沉降正在对全球森林生态系统产生显著影响。目前关于氮沉降如何通过
影响树木不同径级细根碳水化合物含量，进而影响树木生理特征及生长的机制尚不清楚。
本文以 2 年生油松(Pinus tabuliformis)幼苗细根为对象，研究了短期(2 年)氮添加(0、3、6、9
g N·m
－2
·a
－1
，分别记为 N0、N3、N6、N9)对不同径级(0～0．5、0．5～1 和 1～2 mm)细根中非
结构性碳水化合物(NSC)和结构性碳水化合物(SC)含量的影响。结果表明:(1)0～0．5 mm
细根中碳水化合物含量(512．97 mg·g
－1
) 显著低于 1 ～ 2 mm 细根中碳水化合物含量
(638．83 mg·g
－1
)。0～0．5 mm 细根中 NSC、可溶性糖和淀粉含量显著低于 0．5～1 及 1～2
mm;(2)随着细根径级的增加，SC 含量和纤维素含量呈增加趋势，而木质素含量呈降低趋
势。N 添加对 3 个径级细根中不同碳水化合物组分的影响不同。N 添加对 0～0．5 和 0．5～1
mm 细根中 NSC、可溶性糖和淀粉含量均无显著影响，但 N9 处理显著降低了 1～2 mm 细根
中 NSC 和可溶性糖含量(16．20%和 29．90%)，对淀粉含量无显著影响。此外，N3 处理显著
增加了 0～0．5 mm 细根中可溶性糖含量(69．65%);(3)N 添加对细根中 SC、木质素含量没
有显著影响，但 N3 处理显著增加了最细两级根(0～0．5 和 0．5～1 mm)纤维素含量(35．3%
和 57．0%)，N9 处理显著降低了 1～2 mm 细根中纤维素含量(30．39%);(4)N3 处理显著增
加了 0～0．5 mm 细根中 NSC/SC，而对另两级根系中该比率无显著影响。结果表明，N 添加
可能通过影响最细两级根(0～0．5 和 0．5～1 mm)中 NSC、可溶性糖含量及 NSC/SC 影响植
物细根的生理功能和生长。

 Increasing nitrogen (N) deposition significantly affects global forest ecosystems． It is
not clear how N deposition affects carbohydrate contents of different diameter fine roots，which
limits the understanding on the mechanism of plant physiology and growth affected by N deposi-
tion． We set up a N addition experiment with 2-year-old Pinus tabuliformis seedlings to examine
the effects of different N addition levels on nonstructural carbohydrate (NSC) and structural car-
bohydrate (SC) contents in different diameter fine roots． Four N treatments were designed，inclu-
ding N0，N3，N6 and N9 (0，3，6 and 9 g N·m
－2
·a
－1
，respectively)． The results showed
that: (1) the carbohydrate contents (512．97 mg·g
－1
) in fine roots with 0－0．5 mm diameter
were significantly lower than those (638．83 mg·g
－1
) in fine roots with 1－2 mm diameter． The
NSC，soluble sugar and starch contents in the fine roots with 0－0．5 mm diameter were signifi-
cantly lower than those in fine roots with 0．5－1 and 1－2 mm diameter; (2) The SC and the cel-   lulose contents had an increasing trend with the increase of fine root diameter，while lignin con-
tent showed a decreasing trend． Different responses of carbohydrate components in different diam-
eter fine roots to N addition were observed in this study． N addition had no significant influence
on the NSC，soluble sugar and starch contents in the 0－0．5 and 0．5－1 mm fine roots，except that
N9 treatment significantly reduced the NSC and soluble sugar contents in 1－2 mm fine roots (by
16．20% and 29．90%，respectively) and N3 treatment significantly increased the soluble sugar
content in the 0－0．5 mm fine roots (69．65%); (3) Nitrogen addition had no significant influ-
ence on the SC and lignin contents． N3 treatment significantly increased the cellulose content in
0－0．5 and 0．5－1 mm fine roots (35．3% and 57．0%，respectively)，while N9 treatment signifi-
cantly reduced the cellulose content in 1－2 mm fine roots (30．39%); (4) N3 treatment signifi-
cantly increased NSC/SC ratio in the fine roots with 0－0．5 mm diameter，but had no significant
effect on those with 0．5－1 and 1－2 mm fine roots． Our results indicated that N addition may in-
fluence fine root physiological function and growth via affecting NSC，soluble sugar contents and
NSC/SC ratio in the fine roots with 0－0．5 and 0．5－1 mm diameters．