Light environment and carbon gain of understory herbs associated with sunflecks in a warm temperate deciduous forest in Japan |
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Authors: | Hiroshi Koizumi Yasuyuki Oshima |
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Institution: | (1) Division of Plant Ecology, National Institute of Agro-Environmental Sciences, 305 Tsukuba Science City, Ibaraki, Japan;(2) Department of Basic Human Science School of Human Science, Waseda University, 359 Tokorozawa, Saitama, Japan |
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Abstract: | Seasonal variation in the light environment on the forest floor of a deciduous forest was investigated with special reference
to sunflecks. Diurnal variations and seasonal changes in frequency and irradiation period of the sunflecks (sunfleck duration)
were measured. The hourly total sunfleck duration varied seasonally; that is, 30–40 min in spring and autumn and about 15–20
min in summer. There was no large variation in the hourly sunfleck duration during daytime hours (from 9.00 to 15.00 h). The
emergence frequency of sunflecks was 1.3–4.8 per h with two peaks, one in the morning and one in the afternoon. The mean duration
of a sunfleck, however, showed a characteristic daily pattern with a peak around noon. Sunfleck duration was long around noon,
ranging from 12 to 18 min, and short around 10.00 and 14.00 h, ranging from 6 to 10 min. Using the light photosynthesis curves
ofPyrola japonica andSyneilesis palmata (Koizumi & Oshima 1985), the contribution of sunflecks to the dry matter production of these understory species was evaluated.
It was shown that the sunflecks contributed 7–10% of the carbon gain inS. palmata, but only 2–3% of that inP. japonica. |
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Keywords: | carbon gain deciduous forest Pyrola japonica sunflecks Syneilesis palmata |
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