Do coniferous forests evaporate more water than broad-leaved forests in Japan?

SummaryIt is a commonly held belief in Japan, based on a US case study, that coniferous forests evaporate more water than broad-leaved forests. If this is true, converting coniferous forests into broad-leaved forests would result in an increased water yield. However, it is not known whether the US case study is applicable to Japanese forests.A simple model was developed to calculate annual forest evapotranspiration E based on the review of 67 dry-canopy and 16 wet-canopy evaporation studies. We calculated the E values for broad-leaved and coniferous forests under meteorological conditions found in Japan. E of broad-leaved forests was approximately the same as E of young coniferous forests and higher than E of old coniferous forests. The results predicted by the model were supported by water balance data from three Japanese experimental catchments. The conclusion from the data is that coniferous forests do not evaporate more water than broad-leaved forests in Japan.