模拟氮沉降对毛竹非结构性碳的影响

摘要

[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 -2a -1 and zero as control)were applied in the study. Each N-content was replicated for 3 times.[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.