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作 者 ：张胜利,李光录

期 刊 ：生态学报 2007年 27卷 5期 页码：1838~1844

关键词：秦岭；森林生态系统；层次；水质；

Keywords:Qinling Mountain Range, forest ecosystem, sequential components, water quality,

摘 要 ：根据降水与森林生态系统相互作用的空间顺序，分别对火地塘林区火地沟流域大气降水、林内雨、枯透水、支沟溪流水和流域出口径流水质进行了比较分析和变化机理分析。结果表明：森林生态系统不同层次均有使微酸性降水pH值升高的作用，但以林冠层和森林土壤的作用最大，升幅分别为0.58和0.61；森林生态系统对NO^-₃、NH⁺₄、K、PO^3-₄均有净化作用,净化NO^-₃的关键阶段为沟道径流阶段，净化NH⁺₄、K、PO^3-₄的主要方式则为土壤吸附；森林生态系统各层次均增加Ca含量，除土壤外，也增加Mg，但Ca主要来源于土壤和岩石, Mg主要来源于岩石；降水中的Cd、Pb、Mn、Zn经过森林生态系统不同层次的阻减，含量分别降低了0.721μg•L^-1、6.528μg•L^-1、0.0128mg•L^-1和1.4674mg•L^-1,其中以林冠层的阻减作用最大，阻减效果分别为83％、76.7％、54％和99％。总体上，林冠层是净化水质的关键层次，其次为森林土壤。

Abstract:The objective of this study was to investigate the effects of different components of a forest ecosystem on water quality during the rainfall-runoff process. The study area was a small watershed, Huodigou, which is part of Huoditang forest region within the Qinling Mountain Range. For purposes of analysis, the forest ecosystem was divided spatially into four components: canopy, litter, soil, and bedrock. Water samples were collected from rainfall, throughfall, litter drainage, stream water from tributaries within the experimental watershed, and water at the watershed outlet. The samples were analyzed chemically and then compared to determine the effects of different components of the ecosystem on water quality. The analyses indicated that rainfall was slightly acidic, but the pH of the water increased as it moved through each component of the forest ecosystem. The largest increases in the pH were 0.58 units as rainwater passed through the canopy and 0.61 units as water passed through the soil. The NO^-₃, NH⁺₄, K, and PO^3-₄ content of runoff water decreased as it passed through the ecosystem. The largest reduction in NO-3 occurred as water flowed from the tributaries to the watershed outlet. In contrast, the greatest decline in NH⁺₄, K, and PO^3-₄ occurred as water moved through the soil. This is important because the removal of these nutrients from runoff water reduces the probability of eutrophication in the Danjiangkou Reservoir, the main water storage area for the middle line of the South-to-North Water Transfer Project. In general, the Ca and Mg content of water increased as it passed through the ecosystem.The largest Ca increase occurred as water passed through the soil and bedrock, while the main increase in Mg occurred as water passed through bedrock. At the watershed outlet, water contained 0.721μg•L-1 less Cd, 6.528μg•L^-1 less Pb, 0.0128mg•L^-1 less Mn, and 1.4674mg•L^-1 less Zn compared to natural precipitation. Compared to natural rainfall, the throughfall contained 83% less Cd, 77% less Pb, 54% less Mn, and 99% less Zn. Overall, the results from this study show that the canopy has the largest effect and the soil has the second largest effect on water quality in the forest ecosystem.

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