remote sensing of macrocystis with spot imagery surface canopy of giant kelp exhibits high near...

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

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

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)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

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