人造林窗下香椿幼林细根的养分内循环  

Internal Nutrient Cycling of Fine Roots of Toona sinensis Seedings in the Artificial Canopy Gap

作　　者：周义贵[1,2] 刘运科[2,3] 苏宇 李德会[2] 李贤伟[2] ZHOU Yi-gui;LIU Yun-ke;SU Yu;LI De-hui;LI Xian-wei(Sichuan Forestry Inventory and Plan Institute,Chengdu 610081,China;College ofForestry,Sichuan Agricultural University,Chengdu 611130,China;Chengdu Academy ofAgriculture and Forestry Sciences,Chengdu 611130,China)

机构地区：[1]四川省林业调查规划院,成都610081 [2]四川农业大学林学院,成都611130 [3]成都市农林科学院,成都611130

出　　处：《四川农业大学学报》2018年第3期309-314,共6页Journal of Sichuan Agricultural University

基　　金：国家"十二五"科技支撑计划项目(2011BAC09B05);德国政府贷款四川林业可持续经营项目(G1403083)

摘　　要：【目的】通过研究香椿细根在衰老过程中的养分内循环,以期揭示细根在生态系统中物质和养分的循环规律,并为川中丘陵区柏木低效林近自然经营改造提供理论依据。【方法】以川中丘陵区柏木低效林"开窗补阔"改造模式中补植3年后的香椿细根为研究对象,按根序分级法分取1~5级细根,再将细根剥离土壤后置于黑色塑料瓶中,每间隔7 d获取并分析不同根序级细根中氮、磷、钾、钙和镁浓度变化,以确定香椿细根在衰老死亡过程中养分元素是否发生内循环及其内循环速率。【结果】(1)香椿1~5级细根中氮、磷、钾初始浓度均表现为低级细根(1~2级细根)显著高于高级细根(4~5级细根)(P<0.05),钙和镁在根序间差异不显著(P>0.05)。(2)香椿细根衰老过程中氮、磷、钾元素的转移量明显高于钙和镁元素,且在1级细根的养分元素迁移量最多,浓度一直呈下降趋势,在其他根序级中浓度先升后降,表明香椿细根在衰老过程中养分转移是从根轴末端的低级细根开始,依次转移到高级细根上。(3)香椿1~5级细根在衰老过程中氮、磷和钾的平均内循环率分别为16.41%、21.95%和17.09%,养分内循环主要在1~2级细根中,其内循环率远大于3~5级细根,钙和镁在香椿1~5级衰老细根中基本不发生转移。方差分析显示,同一元素在1~2级细根以及3/4~5级细根中的内循环率无显著差异,但1~2级细根内循环率显著高于3/4~5级细根。【结论】香椿细根在衰老过程中氮、磷、钾元素存在明显的内循环,钙和镁基本不发生转移,且养分内循环主要在低级细根中,其内循环率远大于高级细根,即低级细根在物质和养分循环中的作用要强于高级细根。【Objective】Internal nutrient cycling is considered as an important way to efficient utilization.In order to provide a theoretical reference for the close-to-nature forest management model of the degraded C. funebris forests in the hilly region of central Sichuan,this study investigated nutrient internal cycling within fine roots of three-year-old T. sinensis seedings which were enriched in the canopy gaps of the stand.【Method】In this study,the fine roots of replanted T. sinensis in the reconstructing patterns were the subjects. The sampled individual root was dissected according to the branching order method. Fol-lowing the dissection,the fine roots separated from soil were collected in black plastic bottles. The concentrations of nitrogen,phosphorus,potassium,calcium and magnesium of the samples were measured per week in order to determine the internal cycling of nutrient element during the senescence process.【Result】（1） The initial concentration of nitrogen,phosphorus and potassium of the lower roots（1～2 fine roots）was significantly higher than those of the higher ones（4～5 fine roots）（P〈0.05）. However,there was no significant difference（P〈0.05） in calcium and magnesium among the root orders.（2） The migration quantity was different among the different nutrients during the senescing process. The migrated amount of nitrogen,phosphorus and potassium in 1～5 fine roots was significantly higher than calcium and magnesium,the maximum losses of nutrient was observed in the 1 st fine root,where the concentration had been contently declining. While in other roots,the concentration rate showed a pattern of falling after rising,suggesting that during the senescing process the nutrients transfer from the 1～2 fine roots to the higher ones.（3） During the senescing process of the fine roots,the average internal cycling rate of nitrogen,phosphorus and potassium were 16.41%,21.95% and 17.09%,respectively. The internal cycling of nutrients was mainly in 1～2 fine roots,where the

关 键 词：细根 养分内循环 养分迁移 香椿 林窗 

分 类 号：S718.5[农业科学—林学]