森林立地学会誌　森林立地39(2), 1997, 80〜85

Jpn.J.For.Environment 39, 80-85 1997

　

論　文

Radiation budget and soil heat flux at forest

floor in warm-temperate mixed forest

 

 

Koji TAMAI・ Makoto ARAKI・Hiroki ITO

 

 

玉井幸治・荒木　誠・伊東宏樹：暖温帯性混交林の林床面における放射収支と地中熱流量の特性．森林立地39（2），80−85，1997

　京都市に位置する暖温帯性混交林で，林床面における放射収支と地中熱流量の季節変化を測定した。対象とした森林の胸高断面積合計は，常緑樹15.82m²ha^-1,落葉樹12.46m²ha^-1であった。観測地点における開空度の季節変化は着葉期で16％，落葉期で22％とわずかであるにもかかわらず，純長波放射量の季節変化が開葉，落葉の時期と一致すること，純短波放射量の季節変化は3，4月に最大値を示すなど，林床面の放射収支は開空度の季節変化の影響を大きく受けていた。また9，10月に夜間と日中の有効放射量がほぼ等しくなることなど林床特有と考えられる放射収支特性も認められた。

 

　Seasonal change in the radiation budget of a forest floor was measured in a mixed forest located in Kyoto, Japan. The basal area at breast height in the survey forest was about l5.82m²ha^-1 for evergreen trees and 12.46m²ha^-1 for deciduous trees, respectively. The sky view factor was 16% and 22% at the survey site in the foliate and defoliate seasons, respectively. This small difference influenced the seasonal course of radiation budget of a forest floor, Namely, that net long wave radiation changed rapidly in leaving and falling days and that the maximum rate of net short wave radiation was measured in April. Distinctive characteristics of the radiation budget were recognized in the seasonal change that available radiation rates in daytime and night were almost equal in September and October.

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