アベマキ，ミズナラ混交林における遮断蒸発量の観測

九州大学農学部附属福岡演習林内のアベマキとミズナラの混交林において、降水量、樹冠通過雨量、樹幹流量の観測を行い、遮断蒸発量を算出した。2012年4月から2013年3月における降水量、樹冠通過雨量、樹幹流量、遮断蒸発量は、それぞれ1661, 1226, 126, 309mmとなり、降水量に対する樹冠通過雨量、樹幹流量、遮断蒸発量(樹冠通過雨率、樹幹流率、遮断蒸発率)は、それぞれ74%、8%、19%となった。本試験地の遮断蒸発率は、これまでの日本の落葉広葉樹林における観測値と同程度であった。これまでに観測された落葉広葉樹林の遮断蒸発率の最大値は、針葉樹林の最大値と比較して小さいことから、遮断蒸発率の大きい針葉樹林を落葉広葉樹林に転換することで遮断蒸発量を減らせる可能性がある。今後は、落葉広葉樹林における遮断蒸発量の観測値をさらに蓄積することで、上述のことを一般化していくことが望まれる。The objective of this study was to accumulate canopy interception loss (Ic) data for deciduous broadleaved forests. Ic is a major component of evapotranspiration. The number of Ic data for deciduous broadleaved forests was much less than that for coniferous plantations. We observed throughfall (Tf), stemflow (Sf), and Ic in an oak forest. The forest is covered with Quercus variabilis Blume and Quercus crispula Blume trees. Precipitation (Pr), Tf, and Sf during the period between April 2012 and March 2013 were 1611, 1226, 126, 309 mm, respectively. Tf/Pr, Sf/Pr, and Ic/Pr were 74%, 8%, and 19%, respectively. Ic/Pr observed in the study site was within the range of Ic/Pr previously observed in deciduous broadleaved forests. Since the maximum value of Ic/Pr observed in coniferous forests of Japan was larger than that in deciduous broadleaved forests, replacing coniferous plantations with deciduous broadleaved forests could decrease Ic. Further accumulation of Ic data for deciduous broadleaved forests is required to verify the above findings.