scholarly journals Synergistic algorithm for estimating vegetation canopy leaf area index and fraction of absorbed photosynthetically active radiation from MODIS and MISR data

1998 ◽  
Vol 103 (D24) ◽  
pp. 32257-32275 ◽  
Author(s):  
Y. Knyazikhin ◽  
J. V. Martonchik ◽  
R. B. Myneni ◽  
D. J. Diner ◽  
S. W. Running
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Photosynthetically Active Radiation ◽  
Vegetation Canopy ◽  
Area Index ◽  
Active Radiation ◽  
Absorbed Photosynthetically Active Radiation

Light interception and canopy radiation balance of staghorn sumac (Rhus typhina)

2008 ◽  
Vol 38 (6) ◽  
pp. 1695-1700
Author(s):  
Peter M. Lafleur ◽  
Andrew G. Farnsworth
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Photosynthetically Active Radiation ◽  
Solar Zenith Angle ◽  
Radiation Balance ◽  
Area Index ◽  
Mean Values ◽  
Active Radiation ◽  
Rhus Typhina ◽  
Flux Incident

We measured interaction of photosynthetically active radiation (PAR) at a staghorn sumac ( Rhus typhina L.) canopy near Peterborough, Ontario, during summer 2006. Measurements included above-canopy and below-canopy incoming and reflected PAR fluxes and leaf area index (LAI). The ratio of down-welling PAR below the canopy to the flux incident at the top of the canopy (τ) and proportion of incident PAR absorbed by the canopy (fPAR), were calculated. While the canopy was leafless, the sumac stems absorb 10%–20% of incident PAR. LAI increased rapidly during the month of June, and correspondingly τ decreased rapidly while fPAR increased rapidly. Mean values of τ and fPAR at maximum LAI were 0.38±0.09 (SD) and 0.60 ±0.04, respectively. Neither variable showed a relationship with solar zenith angle. We present a simple idealized model of PAR interaction with sumac. Although only one stand was studied, we hypothesize that these results may be more widely applicable to other mature sumac stands.

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