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Spectral properties of tree leaves

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Czarnowski M.

Zeszyty Problemowe Postępów Nauk Rolniczych

1994

tom 405

43-54

Considerable changes in the spectral properties of tree leaves in the vegetation season have been observed. Physiologically active green leaves are characterized by the following optical properties; 1. high absorptance in the PAR range (70 - 90 %); 2. high reflectance (45 %) and transmittance (45 %) in the near infrared; 3. maximum PAR absorptance in the blue and red ranges and a decrease in absorptance in the green range; 4. maximum PAR reflectance and transmittance at wavelengths from 540 - 560 nm; 5. reflectance of the leaf bottom blade surface higher by a few per cent. Owing to the degradation of chlorophyll and changes of colouring, tree leaves in the autumn have completely changed spectral characteristics. They still absorb in the blue range (400 - 500 nm), but with increasing wavelength the absorptance of irradiation gradually decreases. The transmittance spectrum of solar irradiation under the tree crown amounts to about 3 - 5 % in the PAR range and about 7 - 12 % in the near infrared, depending on the leaf area index.

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1 Zeszyty Problemowe Postępów Nauk Rolniczych

1 Czarnowski M.

1 1994

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Spectral properties of tree leaves