Forest hydrological and ecological study on the effects of forest type and its stand age on the quality and quantity of forest runoff water

1990年：在京都大学森林的7个不同年龄的人造杉木林分和4个天然落叶阔叶林分中研究了径流水化学物质。研究每两周进行一次，并与降水进行比较。径流NO_3-N浓度较降水显著降低。径流水和降水中检测到的NH_4-N、org-N和总磷含量基本相同。当径流水量减少到降水的2/3时，可以说森林净化了氮、磷等富营养化物质。1991年：由于该大学林不同林分的径流水化学物质之间没有发现明显差异，我们的调查工作集中在森林调节径流水化学物质的机制细节上。沿森林坡面埋设离子交换树脂，测定渗透土壤的水化学物质量。下坡的化学物质残留量是上坡的数倍。通过土壤溶蚀仪测定土壤水化学物质的试验，发现沿坡面硝态氮由上至下呈递增趋势。硝酸盐的增加也导致钙和镁的增加。1992年：在坡地下部50cm的土壤深度处，检测到高浓度的硝酸盐。为了追踪硝酸盐氮的去向，测量了氮的天然同位素丰度比，并证实了水饱和层的反硝化作用。在连续坡上，土壤的硝化作用和基质饱和度随时间变化，生物因子和环境因子之间存在正反馈相互作用。

1990: Runoff water-chemicals were studied in seven man-made Sugi forest stands of variable ages and four natural and deciduous broad-leaved forest stands at the Kyoto University Forests. Studies were conducted every 2 weeks and compared with that precipitation. NO_3-N concentration in runoff water decreased considerably compared to precipitation. About the same concentration of NH_4-N, org-N, and total-P were detected in runoff water and precipitation. As the amount of runoff water decreased to 2/3 of the precipitation, we can say that the forest purifies eutrophication substances such as nitrogen and phosphorus.1991: As no apparent difference was detected among the runoff water-chemicals of the variable forest stands in this University Forest, our investigation efforts were concentrated into the details of forest mechanisms in regulating runoff water chemicals. Ion exchange resins were buried along the forest slope and the amount of water-chemicals which infiltrate through the soil was measured. At lower slope, the amount of chemicals detected was several times that of upper slope. Through the experiment of soil water-chemicals measurement using lysimeter, an increase of nitrate along the slope was detected from upper to lower slope. The increase of nitrate also brought about an increase of calcium and magnesium.1992: At soil depth of 50cm in lower slope, a high concentration of nitrate was detected. To follow the fate of this nitrate nitrogen, the natural isotope abundance ratio of nitrogen was measured and denitrification in the water saturated layer was confirmed. Along a continuous slope, nitrification and base saturation in the soil changed punctually with the positive feedback interaction between biological and environmental factors.