Abstract
In order to quantify the light conditions of a deciduous broad-leaved forest, we proposed a method to determine the threshold level of the brightness of a hemispherical photograph when converting it into a one-bit screen image. The coefficient of determination was examined for the regression between the measured ISF (indirect site factor) using the quantum sensors and the estimated ISF from the photographs, by changing the threshold level for the photographs. In the range of threshold levels between 60 and 180, the coefficients of determination (r 2) were all significant, andr 2 had a single maximum value at the threshold level of 115. This method was found to be effective for determining a single threshold level without subjectivity at any season.
Literature cited
Anderson, M.C. (1964a) Light relations of terrestrial plant communities and their measurement. Biol. Rev. 39: 425–486.
Anderson, M.C. (1964b) Studies of the woodland light climate I. The photographic computation of light conditions. J. Ecol. 52: 27–41.
Anderson, M.C. (1964c) Studies of the woodland light climate II. seasonal variation in the light climate. J. Ecol. 52: 643–663.
Canham, C.D., Denslow, J.S., Platt, W.J., Runkle, J.R., Spies, T.A., and White, P.S. (1990) Light regimes beneath closed canopies and tree-fall gaps in temperate and tropical forests. Can. J. For. Res. 20: 620–631.
Chazdon, R.L. and Field, C.B. (1987) Photographic estimation of photosynthetically active radiation: Evaluation of a computerized technique. Oecologia 73: 525–532.
Clark, D.B., Clark, D.A., and Rich, P.M. (1993) Comparative analysis of microhabitat utilization by saplings of nine tree species in Neotropical rain forest. Biotropica 25: 397–407.
de Freitas, C.R. and Enright, N.J. (1995) Microclimatic differences between and within canopy gaps in a temperate rainforest. Int. J. Biometeorol. 38: 188–193.
Evans, G.C. and Coombe, D.E. (1959) Hemispherical and woodland canopy photography and the light climate. J. Ecol. 47: 103–113.
Komiyama, A. (1989) Tree age composition and the regeneration process of a secondary deciduous broad-leaved forest. J. Jpn. For. Soc. 71: 374–379. (in Japanese).
Madgwick, H.A.I. and Brumfield, G.L. (1968) The use of hemispherical photographs to assess light climate in the forest. J. Ecol. 57: 537–542.
Monsi, M. and Saeki, T. (1953) Über den Lichtfaktor in den Pflanzengesellschaften und seine Bedeutung für die Stoffproduktion. Jpn. J. Bot. 14: 22–52.
Rich, P.M. (1989) A manual for analysis of hemispherical canopy photograph. Los Alamos National Laboratory Report LA-1773-M. Los Alamos, New Mexico 87545, USA.
Rich, P. M., Clark, D.B., Clark, D.A., and Oberbauer, S.F. (1993) Long-term study of solar radiation regimes in a tropical wet forest using quantum sensors and hemispherical photography. Agric. For. Meteorol. 65: 107–127.
Tamai, S. and Shidei, T. (1972) Light intensity in the forest (II) The hemispherical photographic computation of light intensity (1). Bull. Kyoto Univ. For. 44: 100–109. (in Japanese with English summary)
ter Steege, H. (1993) HEMIPHOT, a Programme to analyze vegetation indices, light and light quality from hemispherical photographs. The Tropenbos Foundation, Wageningen.
Walter, J.-M.N. and Himmler, C.G. (1996) Spatial heterogeneity of a Scots pine canopy: An assessment by hemispherical photographs. Can. J. For. Res. 26: 1610–1619.
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Kato, S., Komiyama, A. A calibration method for adjusting hemispherical photographs to appropriate black-and-white images. J For Res 5, 109–111 (2000). https://doi.org/10.1007/BF02762529
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DOI: https://doi.org/10.1007/BF02762529