樹木根系の存在が森林土壌中の水分移動に与える影響

抄録

Hydrologic properties of soil layer are determined by various kinds of heterogeneities (for example soil pipes, cracks, cobbles and forest roots etc). And these heterogeneities give large influences to hydrologic processes in soil layer. Therefore, it is important to estimate accurately effects that heterogeneities give for water movement in soil layer. In spite of importance of these heterogeneities in soil layer, few studies concerned with these phenomena. In order to understand effects of forest roots (living-root and decayed-root), which are a portion in primary factor to make soil layer structure heterogeneous, on hydrologic processes, that is, water movement in soil layer, field sprinkling experiments were carried out on a hillslope in the Kamiyadono basin where located in upper stream of Shigenobu-Liver. The following matters were confirmed by these field experiments.
1) Rainwater concentrates on the surroundings of forest roots. And, its tendency is enlarged in proportion to an increase of rainfall intensity. Runoff from surrounding of forest roots in steady state increases approximately with rainfall intensity. Runoff from surrounding of forest roots can be approximated lineally with rainfall intensity. Comparison of the observed and calculated runoff from surrounding of forest roots showed that the formula constructed in this study is adequate for the predicting the runoff from surrounding of forest roots.
2) Equivalent hydraulic conductivity at surrounding of forest roots is 1.1-3.2 timeses as large as one of the part of soil matrix. From these results, it is expected that rainwater concentrate on surrounding of forest roots.