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| Titel |
Transmissivity of solar radiation within a Picea sitchensis stand under various sky conditions |
| VerfasserIn |
S. Dengel, J. Grace, A. MacArthur |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 14 ; Nr. 12, no. 14 (2015-07-16), S.4195-4207 |
| Datensatznummer |
250118023
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| Publikation (Nr.) |
 copernicus.org/bg-12-4195-2015.pdf |
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| Zusammenfassung |
We tested the hypothesis that diffuse radiation from cloudy and overcast
skies penetrates the canopy more effectively than direct radiation from clear
skies. We compared the flux density and spectral properties of direct and
diffuse radiation (around solar noon (±1 h)) above, within and below a
forest stand under sunny, cloudy and overcast conditions in a thinned Sitka
spruce (Picea sitchensis (Bong.) Carr.) forest (28 years old, with a
leaf area index of approximately 5.2 m2 m−2). We recorded
vertical profiles of radiation penetration (from 350 to 1050 nm), and we
also explored the horizontal pattern of radiation along a 115 m transect.
We showed that in "clear sky" conditions, the photosynthetically active
radiation in the lower parts of the canopy was substantially attenuated, more
so than under cloudy and overcast skies. It was particularly depleted in the
blue part of the spectrum, but only slightly blue-depleted when the sky was
overcast or cloudy. Moreover, the red : far-red ratio under clear skies fell to
values less than 0.3 but only to 0.6 under cloudy or overcast skies. Near the
ground, the light climate was strongly influenced by the thinning pattern
(carried out in accordance with standard forestry management practice). |
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