三峡库区马尾松细根分解及其养分释放

Fine Root Decomposition and Nutrient Release of Pinus Massoniana in the Three Gorges Reservoir Area

[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、0.5 1 mm和1 2 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、0.5 1 mm和1 2 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,0.5 2 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 examine 〈 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 massoniana, 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 decomposition 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 different root diameter performance status were different, or enrichment, or release.