中文摘要：

以辽宁东部山区16年生日本落叶松人工林为研究对象,探讨施肥对日本落叶松1～5级根序中细根直径、根长和比根长的影响.结果表明：随着根序等级的增加,日本落叶松细根平均直径和根长显著增加（P＜0.05,P＜0.01）、比根长则显著下降（P＜0.01）.在日本落叶松的5级根序中,1级根的平均直径最细、根长最短、比根长最高,而5级根则相反;随着根序等级的增加,日本落叶松细根平均直径、根长和比根长的变异系数逐渐增大.除1级根外,土层对细根的平均直径、根长和比根长没有显著影响（P＞0.05）.与对照样地相比,施肥对各级细根平均直径、根长和比根长的影响主要表现在1～2级根上,对3级根序以上的细根影响不显著（P＞0.05）.其中,施氮肥显著降低了1～2级根的平均直径（P＜0.05）,施氮肥以及氮磷肥显著降低了表层土壤（0～10 cm）中1级根的平均根长（P＜0.05）,表层土壤中细根的比根长在施氮肥的条件下显著增加（P＜0.05）.

英文摘要：

With 16 years old Larix kaempferi plantation in the mountainous area of eastern Liaoning Province as test object, this paper studied the effects of fertilization on the fine root diameter, root length, and specific root length （SRL） of the first to fifth order roots. The results showed that with ascending root orders, the mean fine root diameter and root length increased,.while the SRL decreased significantly. Among the five order roots, the first order roots were the thinnest in diameter, the shortest in length, and the highest in SRL, but the fifth order roots were in reverse. The variance coefficients for the fine root diameter, root length, and SRL increased from the first to the fifth order roots. Except for the first order roots, soil depth had no significant influence on the fine root diameter, root length and SRL. Fertilization affected the fine root diameter, root length, and SRL of the first and the second order roots significantly, but had little effects on other order roots. N fertilization decreased the mean diameter ＋ P fertilization decreased the mean of the first and the second order length of the first order roots in roots significantly, and N or N surface soil （0-10 cm） significantly. The SRL of the first order roots in surface soil increased significantly under N fertilization.