J. Jpn. Soc. Soil Phys. No. +*2, p. +3,2,**2 * ** *** *** Influence Area of Stem Flow on a Soil of Deciduous Forest Floor by Electric Resistivity Survey and the Evaluation of Groundwater Recharge through Stem Flow Jun S HIMADA*, Kyoko O HSUMI**, Kazuhiko O HBA*** and Atsushi M ARUYAMA*** * Graduate school of Science and Technology, Kumamoto Univ., Kumamoto, 20* 2///, Japan ** Ashisuto, Co. Ltd. Tokyo, +*, 2+*3, Japan *** Agricultural Meteorology laboratory, National Agricultural Research Center for Kyushu- Okinawa region, Kumamoto, 20+ ++3,, Japan Abstract The stem flow is volumetrically much less than through fall and it was believed to be less wet around a tree stem than the other part of the forest floor because of rainfall resistance of a tree canopy and little contribution of stem flow. In the present study, the continuous resistivity survey was conducted at the experimental deciduous forest along the one selected line for about +/. years intervals to observe the seasonal change of soil water content under the tree canopy. The observation results were applied to evaluate the e# ect of the stem flow on the shallow soil water content around the selected trees. The results clearly show that the downward soil water flux under the tree canopy is,,. times larger than that of the no tree area in the study forest. By using this downward flux data with tree density in the study forest, the groundwater recharge rate was calculated. The groundwater recharge through the stem flow is nearly -3. + in the total groundwater recharge in the study forest, which is completely larger than the tree density,, of the study forest (*. ++/ m /m ( +. +/ )). This result clearly supports the e# ect of stem flow on the groundwater recharge in the forested area. Key words : stem flow, soil water content, groundwater recharge, resistivity survey +,**1 1* +33/ * 20* 2///, -3 + :
20 +*2,**2, - + -+,**- 0,2,**. +, -+ + +-.+, +- m F -./ a + Herwitz +320 F: + - NEXT-.** RS V : mm event P :, */. m 30 mmevent B : mm.2 m Wenner-. +33/ 0 +.* + + + + F+** VB P *,* mm Tera * +/ RES, DINV. ver. -..3 * +.* mm pf.* mm 1,**, 0 +, 0,0 *+. m, *-. m, */. m, *1. m, +*. m, +/. m, +2. m 1 Fig. + + Layout of observation system in the study Oak forest.
: 21 -,,.2 m +,**- 0,**. +, 0.. a + E + F. b pf */. m, +*. m, +/. m -, 0*+.- mmy pf -, pf, * mmy pf, ad pf,1.. + mmy pf 20/.* mmy pf + -, c -- pf, pf. +,, a b d INFA : m INFA BDH m, + E F INFA 022. BDH *-0. */. m +/. m pf +, 0* m.* m,,,.** m -,, *. ++/ m m /, /.0. 1 m,,. 2, +, 2/-. - m, -
22 +*2,**2 Fig., (a), a,**- pf Two dimensional of pf soil moisture distribution on leafed season in,**-.
: 23 Fig., (b), b,**- pf Two dimensional of pf soil moisture distribution on leafed season in,**- (continued).
24 +*2,**2 Fig., (c), c,**. pf Two dimensional of pf soil moisture distribution on leafless season in,**..
: 25 Fig., (d), d,**. pf Two dimensional of pf soil moisture distribution on leafed season in,**..
26 +*2,**2 - */. m +/. m Fig. - Seasonal fluctuation of soil water flux between */. m and +/. m depths for under-trunk tree forest floor area and for under-no-trunk tree forest floor area. 11., -,. +. +/,,. 2 0*+.- mmy,1.. + -3. + mmy - -,2. 1 m y -3. +. - /++., m y 0*. 3,, *. ++/ m m +. +/,,. 2-32., mmyr *. 3/ mmday -3. +,.- mmday Teramoto et al.,,**-,, *. ++/ m m,**/
: 27. a b Fig.. Seasonal variation of Gross rainfall (a), and monthly total upward and downward soil water flux (b) for under trunk tree forest floor area and under no trunk tree forest floor area.
28 +*2,**2 Fig. / / Groundwater recharge evaluation area in the study forest and the estimated distribution of representative stemflow infiltration contribution area. Herwitz, S.R. ( +320) : Episodic stemflow inputs of mag- nesium and potassium to a tropical forest floor during heavy rainfall events, Oecologia, 1* (-) :,**/ :.,-.,/. Teramoto, M., Yonesaka, T. and Shimada, J. (,**-) : /2 :,+,,+/. Infiltration process and groundwater recharge +33/ : rate in the pyroclastic flow deposits revealed by,*0p. environmental tritium and stable isotopes. Proc.,**1 : p. +2 of IUGG/IAHS Sapporo,**-. A./ +.* :,**1 +,, :,**2, +-