长白山系榛子灌木林根系对优先流的影响

Effect of Plant Root System on Preferential Flow of Hazelnut Shrub in Changbaishan Mountains

[目的]通过调查分析榛子灌木林下不同土层深度内不同根系径级对土壤优先流现象发生程度的影响,了解该区域内土壤水分的运动规律,查看森林系统生态恢复情况。[方法]选取长白山系张广才岭余脉丘陵区内榛子灌木林为研究对象,采用野外示踪法示踪优先流路径分布特征,分析其与不同土层深度下不同径级的根长密度、根生物量的关系。[结果]表明:灌木林内优先流以大孔隙流,漏斗流和环绕流为主,发生迅速,伴有环绕特征。随土壤深度的增加,根长密度逐渐减小,根系径级d<1 mm,1<d<3 mm,3<d<5 mm,5<d<10 mm的根长密度对优先流贡献率分别为67.9%,64.9%、55.2%、59.3%,以d<1 mm根系的优先流贡献率最大,且均值在58.5%以上。根长密度在不同土层深度及不同径级下变幅为2.59%31.2%和1.16%11.07%。研究点内优先流区根生物量大于基质流区,整体仅高出约1.1%,根生物量对优先流路径的发生不起决定性作用。[结论]不同土层内的不同根系径级的根长密度对榛子灌木林下的土壤优先流影响极为明显,d<1 mm影响效果最大,根系生物量对其优先流的产生不起决定性作用。

[Objective] To reveal the effect of root diameter classes on the occurrence of soil preferential flow in different depth of soil layer. [Method] The study area located in the hillslope with hazelnut shrub forest in Zhangguangcailing of Changbaishan Mountains.The blue dye tracing method was applied to confirm and evaluate the changes in root biomass and root length density along preferential pathways in the soil matrix. [Result] The macropore flow, funnel flow and surround flow were the main soil water flow movement patterns which occurred rapidly with surround features. The root length density decreased with the increase of soil depth. In addition, the contributions of root length densities with root diameter （d） 〈1 mm, 1 〈 d 〈 3 mm, 3 〈 d 〈 5 mm, 5 〈 d 〈 10 mm to preferential flow were 67.9%, 64.9%, 55.2%, and 59.3%. The average contribution of plant roots d〈1 mm to preferential flow was almost 58.5% at all the experimental plots. The fluctuation ranges of root length density at different soil depth and different diameter were 2.59%-31.2% and 1.16%-11.07%. The proportion of root biomass in the preferential pathways was 1.1% higher than that in the soil matrix. [Conclusion] The root length density of different root diameter classes in different soil layers has a significant effect on the soil preferential flow under hazel shrub forest. Root diameter d〈1 mm had the greatest effect. The root biomass does not play a decisive role in the occurrence of preferential flow paths.