辽东山区次生林生态系统不同林型树干茎流的理化性质

Physical and chemical properties of stemflow in different forest types of a secondary forest ecosystem in montane regions of eastern Liaoning Province,China

为明确森林对降雨水质的影响,于2011年6—8月,对辽东山区次生林生态系统5种主要林型:落叶松人工林(Larixolgensis)(Lo)、花曲柳林(Fraxinus rhynchophulla)(Fr)、杂木林(Mb)、红松人工林(Pinus koraiensis)(Pk)和蒙古栎林(Querusmongolica)(Om)中树干茎流和林外雨理化性质进行了监测。与林外雨相比,5种林型树干茎流均出现明显酸化(P<0.05),酸化程度为:Pk>Lo>Fr>Om>Mb;各林型树干茎流的电导率、总溶解固体含量、氯离子浓度、硝酸根离子浓度、铵根离子浓度浓度和总磷浓度显著升高(P<0.05),溶解氧浓度明显下降(P<0.05)。林型间相比,Lo与Pk的电导率和总溶解固体含量和Lo的氯离子浓度较高;Lo和Pk的硝酸根离子浓度和总磷浓度明显低于其它林型(P<0.05);Mb的硝酸根离子浓度和总磷浓度显著高于其它林型(P<0.05)。各林型树干茎流的硝酸根离子浓度和胸径与树高的乘积呈显著正相关。上述结果主要受降雨因素(降雨前干沉降时间长度等)、林分特征(叶面积指数、树皮特征)、树木枝叶表层积累物质的理化性质等影响。结论:各林型树干茎流水质均明显下降,其中Mb树干茎流对雨水化学性质影响较大;Pk和Lo树干茎流水体纯度下降最为显著。

To make clear the influence of forests on the water quality of rainfall,the physical and chemical properties of bulk precipitation and stemflow were monitered in five different forest types,i.e.,Larix olgensis stand（Lo）,Fraxinus rhynchophylla stand（Fr）,mixed forest stand（Mb）,Pinus koraiensis stand（Pk）,and Querus mongolica stand（Mo） of secondary forest ecosystems in montane regions of eastern Liaoning Province,China.Comparing with bulk precipitation,the stemflow in five forest types was significantly acidified（P＆lt;0.05）,and the acidification degree was in the order of Pk＆gt;Lo＆gt;Fr＆gt;Mo＆gt;Mb.The conductivity,total dissolved solids,and the concentrations of Cl-,NH＋4,NO-3 and TP of the stemflow increased significantly（P＆lt;0.05）,while the dissolved oxygen concentration of the stemflow lowered significantly（P＆lt;0.05）.Among the five forest types,there were higher conductivity and concentrations of dissolved solids of stemflow in Lo and Pk,and stemflow in Lo had higher Cl-concentration.The concentrations of NO-3 and TP of stemflow in Lo and Pk were significantly lower than those in other forest types（P＆lt;0.05）,and the concentrations of NO-3 and TP of stemflow in Mb were significantly higher than those in other forest types（P＆lt;0.05）.NO-3 concentration of stemflow was significantly positively correlated with the product between diameter at breast height and tree height.These results were mainly influenced by the rainfall factors（e.g.,the length of the dry period before a rain event）,stand characteristics（including leaf area index and characteristics of bark）,and physical and chemical properties of substance of foliage and branch of trees etc.It can be concluded that the water quality of stemflow significantly decreased,representative of the fact that stemflow in Mb has the most effects on the chemical properties of the rainfall,and the water purity of stemflow in Pk and Lo was significantly lower than that of bulk precipitation.