降雨特征对兴安落叶松林降雨再分配过程中钾元素影响分析

[目的]以大兴安岭地区兴安落叶松林为研究对象,分析降雨特征对兴安落叶松林降雨再分配过程中K~+的影响。[方法]对林外降雨、穿透雨、灌木穿透雨、树干径流和枯透水进行了野外观测、取样和室内实验测定。[结果]结果表明:(1)研究期间兴安落叶松林林外降雨总量为266.0 mm,平均次降雨强度0.074 mm·min~(-1);降雨再分配过程中K~+含量平均值排序为枯透水树干径流灌木穿透雨穿透雨林外降雨,其中林外降雨中K~+含量在0.227 2.631 mg·L~(-1)之间,变化幅度较大,穿透雨中K~+含量波动在2.198 3.053 mg·L~(-1)之间,枯透水中K~+含量波动较小,稳定在3.077 3.281 mg·L~(-1)之间。(2)降雨量和降雨历时对降雨再分配过程中K~+含量均表现为正相关,随降雨量和降雨历时的增加K+含量的增加幅度呈上升趋势;而降雨强度和降雨间隔期对K~+含量增加幅度的影响则反之,但当降雨强度大于0.041 mm·min~(-1)时,K+含量的增加幅度开始出现转折,呈上升趋势;当降雨间隔期增大至233.28 h时,K~+含量的增加幅度趋于稳定。(3)影响林外降雨中K~+含量的主导因子是降雨间隔期,影响穿透雨、灌木穿透雨和树干径流中K~+含量的主导因子均为林外降雨量,而对枯透水中K~+含量起主导作用的则为降雨强度。[结论]降雨量、降雨历时、降雨强度以及降雨间隔期均会对降雨再分配过程中各个层次的K~+含量产生不同程度的影响。降雨再分配过程中K~+含量平均值大小排序为枯透水树干径流灌木穿透雨穿透雨林外降雨,其中大气降雨中K~+含量在5月和9月较高,穿透雨中K~+含量在5—10月呈波动式变化,灌木穿透雨中K~+含量变化幅度较大,而树干径流和枯透水中K~+含量较稳定。降雨量和降雨历时对降雨再分配过程中K~+含量的影响均表现为正相关。对林外降雨中K~+含量影响程度由大到小排序依次为降雨间隔期降雨强度降雨历时降雨量,穿透雨中K~+含量与各影响因素的灰关联度大小顺序依次为降雨量降雨历时降雨强度降雨间隔期,灌木穿透雨和树干径流中K~+含量与各影响因素的灰关联度排序和穿透雨一致,影响的主导因子均为降雨量,枯透水中K~+含量与各影响因素的灰关联度大小顺序依次为降雨强度降雨间隔期降雨历时降雨量。

Analysis on the Effects of Rainfall Characteristics on Potassium Content in Larix gmelinii Forest during Rainfall Redistribution

[Objective]Selecting Larix gmelinii forest in Great Xing''anling Mountains as a research object, to analyze the effects of rainfall characteristics on potassium content in L. gmelinii forest during the process of rainfall redistribution. [Method]The precipitation, throughfall, shrub throughfall, stem flow and litter water were observed, sampled and measured. [Result]The results showed that:(1)During the observation period, the rainfall outside of stands was 266.0 mm, the average rainfall intensity was 0.074 mm·min^-1; the order of the average content of K⁺ during the rainfall redistribution was litter water > stem flow > shrub throughfall > throughfall > precipitation, the content of K⁺ during precipitation changed greatly, the value fluctuated between 0.227~2.631 mg·L^-1, the stem flow fluctuated between 2.198~3.053 mg·L^-1, the content of K⁺ in litter water was the most stable, fluctuated between 3.077~3.281 mg·L^-1. (2) It was found that the content of K⁺ increased with the increase of rainfall and rainfall duration. However the rainfall intensity and inter-events interval were just the opposite unless the rainfall intensity was higher than 0.041 mm·min^-1. When the rainfall interval increases to 233.28 h, the increase of the content of K⁺ became stable. (3) The leading factor influencing the K⁺ content in rainfall outside stand was the rainfall interval. The key factor influencing the K⁺ content in throughfall, shrub throughfall and stem flow was the precipitation. The rainfall intensity was the key factor influencing the K⁺ content of litter water. [Conclusion]The Precipitation, rainfall duration, rainfall intensity and rainfall interval would influence the K⁺ content during the process of rainfall redistribution in varying degrees.