广西主要人工林地坡面径流水质特征

Slope Runoff Quality of Dominant Plantation in Guangxi

为探讨广西主要人工林对坡面径流水质的影响,通过简易径流场收集水样,分别对种植为2008年4月（08EU）、2006年4月（08EU）和2002年4月（08EU）的桉树（Eucalyptus urophylla×E.grandis）人工林以及2002年4月种植的杂交相思（Acacia mangium×A.auriculaef,AM）和马尾松林（Pinus massoniana,PL）坡面径流色度、浊度、pH、化学需氧量（COD）、总N和总P等进行了2年的监测.结果显示：①桉树成熟林坡面径流色度分别为杂交相思和马尾松林的3.6～5.6和2.1 ～2.2倍,pH值显著高于马尾松林而低于杂交相思林;②桉树林坡面径流色度、pH值以及COD随林龄增加而显著提高,pH值和COD由幼龄林的4.36和26.8 mg·L-1逐渐升高至成熟林的5.47和388.4 mg·L-1,但总N和总P含量差异不显著;③距上次暴雨间隔时间越长,桉树林坡面径流色度、COD、总N和总P含量越高,pH值越低,降雨特征对幼龄和中龄按树林水质的影响大于成熟林、杂交相思和马尾松林;④清除凋落物显著增加桉树人工林坡面径流浊度、总N和总P含量,降低pH值、色度和COD.凋落物是桉树人工林影响地表水色泽、COD的关键因子,桉树凋落物自身特性与易分解性是桉树林区地表水颜色变深的主要原因,而浊度和总N含量主要受土壤侵蚀影响.

To better understand the impact of dominant plantation on slope runoff water quality in Guangxi Province,slope runoff samples of eucalyptus（Eucalyptus urophylla × E.grandis） forest planted in April 2008 （08EU）,April 2006 （06EU） and April 2002 （02EU） as well as hybrid lovesickness（Acacia mangium × A.auriculaef） forest planted in April 2002 （AM） and Pinus massoniana forest planted in April 1996 （PL） were collected during storm events from simple flow fields.The samples were analyzed for color,turbidity,pH,chemical oxygen demand （COD）,total nitrogen （TN） and total phosphoms （TP） for two years.Compared with AM and PL treatment,slope runoff colority of mature eucalyptus plantation increased 3.6-5.6 and 2.1-2.2 times,respectively.The runoff pH of eucalyptus plantation was significantly lower than AM but higher than PL.The runoff colority,pH,and COD increased with forest age in eucalyptus plantation.Runoff pH increased from 4.36 of young eucalyptus plantation to 5.47 of grown eucalyptus plantation.Runoff COD increased from 28.6 mg · L-1 of young eucalyptus plantation to 388.4 mg · L-1 of grown eucalyptus plantation.No significant difference was observed in rnoffTN and TP between different ages of eucalyptus plantation.Long storm interval in planted forests increased colority,COD,TN and TP of slope runoff,but decreased pH.Litter fall removal significantly increased the turbidity,TN and TP in slope rooff from eucalyptus plantation,while decreased the pH,colority,and COD.The fast decomposing litter fall is the key factor determining the water color and COD property.Soil erosion determines the turbidity and TN of runoff.