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Estimation of relative photon flux density within stands of conifer/deciduous broad-leaved mixtures  [2002]

Kunisaki, T. (Iwate Univ., Morioka (Japan). Faculty of Agriculture)

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Abstract
Light environment within stand of conifer/broad-leaved mixtures was investigated in northern part of Japan. Two conifers, Cryptomeria japonica (Cj) and Pinus densiflora (Pd) were planted and broad-leaved species (BL) regenerated naturally in plantation sites. Sky factor which is theoretically equal to relative illuminance was calculated based on digital images of hemispherical photographs within stands. Photon flux density (PFD) at stands and open site was measured using quantum sensors under cloudy condition, and relative PFD (the ratio of PFD at stand to that at open site) was calculated. The results obtained were as follows. 1) Relative PFD was positively correlated with sky factor for Cj/BL and Pd/BL mixtures. 2) Relative PFD of Cj/BL mixtures initially decreased with time until early June, does not change until late August, but then increased by early November. Seasonal change in relative PFD was probably reflected to leaf phenology pattern of Cj/BL mixtures. 3) Mean relative PFD in November was 11.6% for Cj/BL and 18.9% for Pd/BL mixtures, and these values were the same as relative PFD of Cj and Pd pure stands, respectively. 4) On the other hand, mean relative PFD in August was 6.7% for Cj/BL and 6.2% for Pd/BL mixtures, and these values were the same as relative PFD of closed deciduous braod-leaved stands.
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Other subjects

  • mixed forests
  • cryptomeria japonica
  • light regimes
  • pinus densiflora
  • photography
  • broadleaved trees

From the journal

Bulletin of the Iwate University Forests (Japan)

ISSN : 0286-4339

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