Ecological Research

, Volume 3, Issue 3, pp 253–266 | Cite as

Fluctuation of photosynthetic photon flux density within aMiscanthus sinensis canopy

  • Yan-Hong Tang
  • Izumi Washitani
  • Takayoshi Tsuchiya
  • Hideo Iwaki


Detailed measurements of diurnal variations in photosynthetic photon flux density (PPFD) were made at seven locations within the canopy of aMiscanthus sinensis grassland to evaluate the light conditions of microsites for heliophilic tree seedlings. Multiple regression analysis revealed that the short-term light fluctuation on a clear day was highly dependent on the wind speed and solar elevation angle, whereas on a cloudy day it was mainly determined by the PPFD incident from above the canopy.

The relative PPFD at 40 cm aboveground varied from 0.065 to 0.252, depending on sky conditions and the sensor's position in relation to clumped patches ofM. sinensis. On a clear day, the proportion of PPFD readings above 100 μmol·m−2·s−1 contributed by sunflecks ranged between 25.4% and 82.0%. Computer simulation showed that the contribution of sunflecks to the daily carbon gain ofQuercus serrata seedlings may range from 11% to 65%.

The mean relative PPFD measured under diffuse light conditions was linearly related to the daily total PPFD and the daily carbon gain by single leaves ofQ. serrata seedlings. This suggests that the relative PPFD under diffuse light conditions provides an appropriate measure of site-specific light availability within a grass canopy.

Key words

Light fluctuation Microsite Miscanthus sinensis Photosynthetic photon flux density Sunflecks 


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Copyright information

© Ecological Society of Japan 1988

Authors and Affiliations

  • Yan-Hong Tang
    • 1
  • Izumi Washitani
    • 1
  • Takayoshi Tsuchiya
    • 1
  • Hideo Iwaki
    • 1
  1. 1.Institute of Biological SciencesUniversity of TsukubaTsukuba, IbarakiJapan

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