A Consideration for the Light Environmental Modeling under Tropical Rainforest Canopies
Photosynthetic Active Radiation (PAR) is the most important light source for plant photosynthesis. It is known that most of PAR from solar radiation is well absorbed by the surface. The canopy is the surface in forest region, consists an aboveground portion of plant community and formed by plant cro...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-09-01
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| Series: | The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| Online Access: | http://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XL-7/217/2014/isprsarchives-XL-7-217-2014.pdf |
| Summary: | Photosynthetic Active Radiation (PAR) is the most important light source for plant photosynthesis. It is known that most of PAR
from solar radiation is well absorbed by the surface. The canopy is the surface in forest region, consists an aboveground portion of
plant community and formed by plant crowns. On the other hand, incident solar radiation is fluctuating at all times because of
fluctuating sky conditions. Therefore, qualitative light environmental measurements in forest are recommended to execute under
stable cloudy condition. In fact, it is quite a few opportunities to do under this sky condition. It means that the diffuse light condition
without the direct light is only suitable for this measurement.
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In this study, we challenged the characterization the forest light environment as its representativeness under no consideration of sky
conditions through analysis huge quantities of instantaneous data which obtained under the different sky conditions. All examined
data were obtained under the different sky conditions at the tropical rainforest canopy as one of the typical fluctuating sky conditions
regions. An incident PAR is transmitted and scattered by different forest layers at different heights. Various PAR data were
measured with quantum units as Photosynthetic Photon Flux Density (PPFD) at different forest heights by the quantum sensors. By
comparing PPFDs at different heights with an incident PPFD, relative PPFDs were calculated, which indicate the degree of PPFD
decrease from the canopy top to lower levels. As the results of these considerations, daily averaging is confirmed to be cancelled sky
fluctuating influences. |
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| ISSN: | 1682-1750 2194-9034 |