摘要
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、9g 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1~2mm;(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0.5~1mm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 deposition. 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 carbohydrate （SC） contents in different diameter fine roots. Four N treatments were designed, including 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 significantly lower than those in fine roots with 0.5-1 and 1-2 mm diameter; （2） The SC and the cellulose contents had an increasing trend with the increase of fine root diameter, while lignin content showed a decreasing trend. Different responses of carbohydrate components in different diameter 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 influence 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 significantly reduced the cellulose content in 1-2 mm fine roots （30.39%）; （4） N3 treatment significa
出处
《生态学杂志》
CAS
CSCD
北大核心
2017年第8期2184-2190,共7页
Chinese Journal of Ecology
基金
国家自然科学基金项目(41371508)
国家"十二五"科技支撑课题(2015BAC01B03)资助
关键词
氮沉降
油松幼苗
细根
径级
非结构性碳水化合物
结构性碳水化合物
nitrogen deposition Pinus tabuliformis seedlings fine root diameter class nonstructural carbohydrate structural carbohydrate.
