J. Jpn. Soc. Soil Phys. No. +*-, p.-3.1,**0 ** * *** Comparison of Evapotranspiration between Indigenous Vegetation and Invading Vegetation in a Bog Toshiki FUJIMOTO*, Ippei IIYAMA*, Mai SAKAI*, Osamu NAGATA** and Shuichi HASEGAWA* * The Graduate School of Agriculture, Hokkaido University, Sapporo *0*2/23, Japan ** National Agricultural Research Center for Hokkaido Region, Sapporo *0,2///, Japan Abstract To assess the e#ect of vegetation change on water balance in terms of wetland ecosystem conservation, we evaluated the evapotranspiration, the largest output from the Bibai mire, with the lysimeter method in a bamboo grass-invading area and in a Sphagnum bog. Cumulative evapotranspiration in,**. and,**/ except for snow season was greater in the Sphagnum bog than in the bamboo grass-invading area. Therefore, we should deny a hypothesis such that because the bamboo grasses had higher ability of evapotranspiration than the indigenous plants, groundwater table lowering would take place when the bamboo grasses invaded into the Sphagnum bog, resulting in the expansion of the bamboo grass-invading area even more into the indigenous vegetation area. Based on the measured evapotranspiration rates under several groundwater table levels in the lysimeter method, we concluded that the Sphagnum growth would not be disturbed even if groundwater table level dropped down to,* cm while the evapotranspiration rate in the bamboo grass area would be a#ected significantly with groundwater table level changing. And from comparison of the data from the lysimeter method with those from the other two methods, it was suggested that the lysimeter method can evaluate the evapotranspiration rate in a field scale as precisely as the Bowen ration method or the Penman method. Key words : evapotranspiration, lysimeter method, water table, bamboo grass-invading area, Sphagnum bog + 0 ha +33. +333 +33/ * *0*2/23 3 3 ** *0,2/// + :
40 +*-,**0 2* +33.,,+ /.* m..* m,. ha + / m - m Sasa palmata Rhus trichocarpa Myrica gale var. tomentosa Ledum palustre var. diversipilosum Shphagnum papillosum Lindb., ha,,, -*.0,0,3 cm +* cm +** cm /,/ cm *,* cm / cm / +/,/ cm - /,* cm, -, mm,**-,**.,**/. ++ Fig. + + Experimental site in the Bibai mire., Fig., f : L: Illustration of a lysimeter, f is diameter and L is length.
: 41 +/ cm / cm,**- / /,/ cm,* cm,**. /,**/ SlEHG S le l : E : H G HlE b, b H T+T, g le e +e, g hpa + T +, T,, e +, e, +, hpa le SG +b GCzTt n C J cm - + z Tt n t / C,.*+V s..+3v w V s,v w V s V w C,./ Jcm - + Dalton +33- le g S g g lfu,esaea hpa + f u, *.,0 + u,+** mm hpa + day + u,, m e sa hpa e a hpa +.** +/* cm Q1 REBS +/* -/* cm, /* cm + HMP-./ VAISALA 3* cm fetch cm cm/*+-* m,/* cm *-.S, METONE u,./ u,u,./ log,** log +**H u, H,./ m, / +*,* -* cm / +* -/* cm STS +,**/ 1 *+* +*/* /* cm - -+ /,* cm -
42 +*-,**0 / +/,/ cm - S+S- S.S0 S1 S3 / cm S+S-,3 ++ +. S+ S, S- +.. +/ cm S.S0 /* /0 0+ /* cm S 0 S. S/ +.,,/ cm S1S3 2. 1-00 +.. : + : +.3 /* cm 3 / +. /* cm - -, +,**.,**/ +/ cm,/ / cm - / cm /+* cm +/,/ cm,**. 2,**/ 2 +320 + 2,**.,**/ 2 2 +/ cm,/ cm +/ cm,/ cm,**. -. -. +,**.,**/ +.,,**. 2,**/ 2,* cm -- --+,**/ /, 2,.,.3 mm Table + + Average values of evapotranspiration measured with lysimeters during three years. mm d + / cm +/ cm,/ cm / cm,* cm,**- / +. ++ +2,4, -4+,**. / +0 ++ 2 +4-,41 +40-4,,41,**/ / 0 ++ + +4-,41,4+ -4*,40
: 43 Fig. - - Seasonal variations of evapotranspiration and groundwater table at the bamboo grass area. d + / +/,/ cm +./ -.,,.. mm d + -./ mm d + *.32 *.33 - b /, 2,. ++., cm +/ cm 0 1 +/ cm,/ cm +/ cm - b 0 1 - b +/ cm /+* cm +,**.,**/ / +/ cm,/ cm,**. *./ mm d +,**.,**/ +0.1 +0./ / cm +,
44 +*-,**0 Fig... Seasonal variations of evapotranspiration and groundwater table at the sphagnum area. +/ cm, -,,**.,**/ / +/ cm,,/ cm +,**. +/ cm +,**-,**. *./ mm d +,**-,**- +./ + +/ cm,**.,**/ /,/ cm,**/ --,. b,**/ / 0 ++ + 1., cm,,.- cm,* cm -.,,.3 mm d + +. b -. /,**.,**/
: 45 Fig. / / Cumulative amounts of evapotranspiration and rainfall at the bamboo grass area and Sphagnum area. +/ cm / cm 0 3 0 3,**/ 2 / -+ 3 +,**..,+ / -+ 3 + ++ 2 +./ *.2 mm d +,**/ /, / -+ 3 + ++ + +.1 *./ mm d + 0 0,**/ 2 +/ cm S.S0 S. S/ S0,- mm d + S0 +/ cm,**/ 2 ++ +33, 1*2* 2* +**,* -*
46 +*-,**0,**+. -, - +/ cm,/ / cm / cm,/ cm /,* cm,* cm + 0 1*2* 2*+**,**+ : +1- : +-0. +33. : 0/ - : -,0---. +33, :.. : +3,0. +33- : +0. : +/1+0-. +333 : /+ : +2/+23. +320 :, :.10/. +33/ : 0- - :,.3,/..
: 47,* cm :,**0 + / :,**0 / +3