Post on 29-Jan-2016
Remote Sensing of Macrocystis with SPOT Imagery
• Surface canopy of giant kelp exhibits high near infrared (NIR) reflectance
• SPOT imagery well suited to differentiate kelp
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Wavelength (nm)
Ref
lect
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(re
l)
Mature Kelp R
Immature Kelp R
Senescent Kelp R
Seawater
SP
OT
ba
nd
3 (N
IR)
SP
OT
ba
nd
2 (r
ed)
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OT
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ree
n)
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0.05
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400 450 500 550 600 650 700 750 800 850 900 950 1000
Wavelength (nm)
Ref
lect
ance
(re
l)
Mature Kelp R
Immature Kelp R
Senescent Kelp R
Seawater
SP
OT
ba
nd
3 (N
IR)
SP
OT
ba
nd
2 (r
ed)
SP
OT
ba
nd
1 (g
ree
n)
Kelp Canopy Delineation• Utilizes the high NIR reflectance of kelp canopy
– 2 calculations performed on the atmospherically corrected image: principal components (PC) rotation and NDVI (Normalized Difference Vegetation Index)
– PC band 2 expresses variations in NIR reflectance– Kelp covered pixels show high PC band 2 and NDVI values
Canopy Delineation Process
SPOT 3,2,1 image SPOT 3,2,1 stretched image
3(NIR)/1(green) band ratio
Kelp delineation
NDVI image
PC band 2 image
Canopy Cover Validation • Normalized SPOT cover measurements compared
with normalized high resolution 2004 CDFG aerial kelp survey
y = 0.96x + 0r2: 0.92p: < 1*10-12
SBC-LTER SCUBA Measurements of Frond Density and Biomass
• Monthly SCUBA measurements of frond density and biomass made at Arroyo Quemado (AQUE), Arroyo Burro (ABUR), and Mohawk (MOHK) kelp beds.
SBC-LTER SCUBA Measurements of Frond Density and Biomass
Satellite Biomass Estimation• Normalized Difference Vegetation Index (NDVI)
(NIR-RED)(NIR+RED)
• Calculated for areas of kelp cover
NDVITransform
LTER transectat Mohawk
NDVI Comparison with LTER SCUBA Measurements
r2 = 0.48p < 1*10-5
y = 14.17x + 0.74
r2 = 0.71p < 1*10-10
y = 14.33x - 0.13
Regional Kelp Biomass Maps
• Created from biomass-NDVI regression• Calculated by pixel, kelp patch, or administrative
bed
Beds 21-30 (11/01/2006) : ~8,600 metric tons wet weight
Arroyo Quemado Time Series 200602/09/2006 04/13/2006 06/04/2006
08/15/2006 11/01/2006 12/23/2006
1475000 kg 1345000 kg 1688000 kg
883000 kg 827000 kg 1013000 kg
Arroyo Burro & Mohawk Time Series 2006
02/09/2006 04/13/2006 06/04/2006
08/15/2006 11/01/2006 12/23/2006
0 kg 6281 kg 11200 kg
104600 kg 229000 kg 63300 kg