模拟氮沉降对毛竹非结构性碳的影响

Effects of Simulated Nitrogen Deposition on Non-Structural Carbohydrates of Moso Bamboo

【目的】分析不同强度氮沉降对毛竹体内非结构性碳水化合物(NSC)含量的影响,为全面认识氮沉降对毛竹林生态系统的影响提供科学依据。【方法】在临安市毛竹林长期试验基地,采用典型选样法,设置12块20 m×20 m样地,包括低氮(30 kg·hm^(-2)a^(-1))、中氮(60 kg·hm^(-2)a^(-1))、高氮(90 kg·hm^(-2)a^(-1))和对照(0 kg·hm^(-2)a^(-1))4种处理,每处理设3个重复样地,处理32个月,探讨模拟氮沉降对1龄和3龄毛竹NSC含量的影响。【结果】可溶性糖和淀粉在NSC中所占比例分别为80%和20%,NSC主要以可溶性糖的形式存在;竹叶NSC含量最高,分别是枝和秆的1.32和1.27倍;3龄竹枝和秆NSC含量显著高于1龄竹(P<0.05),竹龄对竹叶NSC含量影响不显著(P>0.05);氮沉降显著降低毛竹叶、3龄竹枝和1龄竹秆的NSC含量(P<0.05);氮沉降和竹龄的交互作用对毛竹枝、秆的NSC含量影响显著(P<0.01),对毛竹叶影响不显著。【结论】氮沉降显著影响毛竹地上器官的NSC含量及其分配,且随竹龄而显著变化,高强度的氮沉降不利于毛竹NSC的积累和固碳。

【Objective】 The subtropical zone in south-central China has become the region with the greatest nitrogen（ N） deposition in the world. Most moso bamboo（ Phyllostachys edulis） plantations of China are distributed in the center of this region. The change of non-structural carbohydrate（ NSC） in plant can reflect the effects of environmental factors on plant. However,the effects of N deposition on NSC content of moso bamboo remain unclear. The aim of this study is to estimate the effects of N deposition on the NSC contents of leaf,branch and trunk of moso bamboo at different growth stages.【Method】 The experiment was conducted in moso bamboo plantations over a 32-month period and included 4 N content levels（ 30,60,90 kg·hm^（-2）a^（-1）and zero as control） were applied in the study. Each N-content was replicated for 3times.【Result】 The soluble sugar and starch accounted for 80% and 20% of NSC,respectively. Bamboo leaf has the highest NSC content,1. 32 and 1. 27 times higher than branch and trunk,respectively. The NSC content of branch and trunk of 3-year-old bamboo were significantly higher than that of 1-year-old bamboo（ P〈0. 05）. No significant effect of moso bamboo age on the NSC content of leaf was observed（ P〈0. 05）. The NSC content of leaf and branch of 3-year-old bamboo,and trunk of 1-year-old bamboo（ P〈0. 05） was significantly decreased by N deposition. The interaction between N deposition and moso bamboo ages significantly influenced the NSC content of branch and trunk（ P〈0. 01） but not leaf were. 【Conclusion 】 The content and distribution of NSC in moso bamboo were significantly impacted by N deposition,and these effects varied significantly with the bamboo ages. Our result indicated that the excessive atmospheric N deposition（ ≥ 90 kg·hm^（-2）a^（-1）） in the future would restrain the NSC accumulation in moso bamboo and thus its carbon sequestration capacity.