森林樹木と土壌間における雨水の挙動 ―現地測定と浸出・透過実験 [in Japanese] Behavior of rainfall between stem flow and soils in the woods ; Field study and laboratory tests of leaching and absorption elements [in Japanese]
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Field and laboratory studies were conducted to investigate the successive changes in the chemical and physical characteristics of rainwater through stemflow as well as soil in three different forest ecosystems. That is, Sugi (Cryptomeria japonica), Konara (Quercus serrata), and Mousoutiku (Phyllostachys heterocycla) forests which are located in the Kakuma campus of Kanazawa University, Ishikawa Prefecture, Japan. Rainwater outside those forests was also sampled as control precipitation. For field investigation, the rainwater samples as throughfall and stemflow were collected from February 25 to March 18, 2004. For laboratory investigation, the batch leaching experiment using control rainwater was performed over a period of one week, and the continuous filtration experiment using downflow soil bed system with the stemflow of those trees was undertaken as well. XRD analyses of bulk soil and < 2 μ m fraction of soil samples collected from those forests showed similar mineral compositions composed of quartz, feldspars, cristobalite, gibbsite, chlorite, vermiculite, and kaolin minerals. The leaching experimental data showed similar mineral decreases in the rainwater pH of Sugi forest (pH〜4), while little change in the rainwater pH of Konara forest was observed. Conversely, the rainwater pH of Mousoutiku forest tended to increase. These pH changes may be the result of dissolution of K and Ca contained in the bark of those trees in agreement with the experimental data of chemical composition of rainwater analyzed by ED-XRF. Scanning electron microscopic observations of tree bark showed that the surfaces of bark after leaching became smoother than those before leaching, and their EDX spectra showed that there were decreases in the K and Ca contents after leaching. The continuous filtration experiment demonstrated that there were significant changes in the pH, EC, and Eh of the effluent rainwater after filtering through a soil filter bed with several kinds of minerals, indicating that minerals serve as a natural buffer. These results indicate that the type of plants and mineralogical composition of soils in forest ecosystems have effects on the successive changes in the chemical and physical characteristics of rainwater.
- Earth Science (Chikyu Kagaku)
Earth Science (Chikyu Kagaku) 58(6), 389-405, 2004
The Association for the Geological Collaboration in Japan