三峡库区马尾松细根分解及其养分释放

摘要

[目的]为认识马尾松细根对土壤养分库的贡献，[方法]本研究以三峡库区秭归县九岭头林场马尾松为研究对象，采用埋袋法进行细根分解实验，探讨＜0．5 mm、0．51 mm 和12 mm 细根的分解动态和养分释放（C、N、P、K、Ca、Mg）。[结果]结果表明：（1）细根分解368 d 后，＜0．5 mm、0．51 mm 和12 mm 细根干重残留率分别为66．0％、72．0％和74．33％，且细根分解速率随直径增加而减小；（2）细根分解速率与土壤温度呈显著正相关关系（p＜0．05），与土壤湿度呈正相关关系（p ＜0．05）；（3）细根 C、K 和 Mg 元素迁移模式表现为释放，Ca 元素表现为富集；（4）细根 N、P 元素在不同径级细根中迁移模式不同，＜0．5 mm 细根 N、P 元素表现为释放，0．52 mm 细根 N、P 元素在分解过程中出现富集阶段。[结论]马尾松细根分解与土壤温度和直径大小显著相关，其中分解与温度呈正相关，与直径呈负相关；在细根分解过程中，马尾松细根不同直径大小的不同养分元素的表现状态不一致，或富集，或释放。%Objective]The purpose of this study is to determine the contribution of fine root of Pinus massoniana L.on soil nutrient pool.[Method]Decomposition experiment,using the buried bag method,was conducted to ex-amine <0.5 mm,0.5 1 mm and 1 2 mm fine root decomposition dynamics and nutrient release (C,N,P,K, Ca,Mg)in Pinus massoniana at Jiulingtou Forest Farm of Zigui county,Three Gorges Reservoir Area,China. [Result]The results showed that:(1)the decomposition rate decreased with root diameter increasing of Pinus mas-soniana,and after 368 days,the remaining percentage of <0.5 mm,0.5 1 mm and 1 2 mm fine root were 66.0%,72.0% and 74.33% respectively.(2)The soil temperature had significant positive effect on decomposi-tion rate,and soil moisture had positive effect on decomposition rate.(3)The transfer model for C,K and Mg of fine root was releasing,while enriching for Ca.(4)The transfer models for N and P of <0.5 mm,0.5 1 mm and 1 2 mm fine root were different,the transfer models for N and P of <0.5 mm fine root were releasing,but N and P of 0.5 2 mm fine root appeared enriching stage during the decomposition process.[Conclusion]Fine root decomposition rate of Pinus massoniana and soil temperature significantly positivel correlated,andy decomposition rate and diameter significantly negatively correlated;In decomposition process,different nutrient elements of differ-ent root diameter performance status were different,or enrichment,or release.