福建柏和杉木人工林细根N、P养分含量动态

研究细根养分含量的4种动态：（1）福建柏和杉木人工林细根N、P含量的差异；（2）细根N、P含量与细根直径的关系；（3）在细根衰老过程中是否发生N、P的转移；（4）细根N、P含量是否有季节性的变化．从1999年1-12月隔月应用连续根钻法对福建三明莘口林场福建柏和杉木人工林细根进行取样并测定活、死细根的N、P养分含量．结果表明：福建柏人工林细根的N、P含量均比杉木人工林略大，且两者的N、P含量均随细根径级的减小而增加；各径级死细根的N、P含量均略低于相应的活细根，说明细根在衰老过程中发生了养分的转移但迁移量很小；福建柏各径级细根N、P含量的动态变化表现为单峰型，在9月最高；杉木各径级细根N、P含量的动态变化亦表现为单峰型，N含量高峰出现在9月，而P含量则在9月或11月最高．

Dynamics of N and P Concentrations in Fine Roots of Plantations of Fokienia hodgingsii and Cunninghamia lanceolata

These are examined:(1) the difference in nutrient concentrations of fine roots between Fokienia hodginsii and Cunninghamia lanceolata,(2) the relationship between N,P concentrations and fine root diameter,(3) whether N and P restranslocation occurs prior to root senescence,(4) whether there exist seasonal fluctuation of N and P concentrations in fine roots.During January 1999 to December 1999,the concentrations of N and P were measured for fine root samples collected from sequential cores at bimonthly intervals in plantations of Fokienia hodginsii and Chinese fir(Cunninghamia lanceolata(Lamb.) Hook.) in Sanming,Fujian.The result show: Concentrations of N and P in Fokienia hodginsii plantations for fine roots were slightly higher than in Cunninghamia lanceolata plantations.Mean concentrations of N and P in both live and dead roots decreased with the fine root diameter increasing.Comparisons of N and P concentrations in living roots and dead roots showed that the restranslocation of N and P from senesced fine roots was small.For Fokienia hodginsii of plantations,seasonal changes of N,P concentrations for fine roots of various diameter classes showed a single-apex curve with a maximum in September.For Cunninghamia lanceolata,fine roots of various diameter classes also showed a single-apex curve witha maximum concentration of N in September and maximum P concentration in September or November.