Near surface spectral measurements of the land surface Heidi Steltzer [email protected]...
13
Near surface spectral measurements of the land surface Heidi Steltzer [email protected] Plant and Ecosystem Ecologist Natural Resource Ecology Laboratory (NREL)
-
date post
22-Dec-2015 -
Category
Documents
-
view
216 -
download
1
Transcript of Near surface spectral measurements of the land surface Heidi Steltzer [email protected]...
Near surface spectral measurements of the land surface
Heidi [email protected]
Plant and Ecosystem EcologistNatural Resource Ecology Laboratory (NREL)
SpecNet – a spectral network
• http://specnet.info
Advantages of near surface spectral measurements
• Scaling– Spatial
• fine resolution imagery• pure pixels
– Temporal• frequent observations
Spatial variability in plant coverComplex or brief growing season
Short grass steppe Patterned ground in the Arctic
NDVI
0.0
0.2
0.4
0.6
0.8
1.0
Increasing NDVIplot
Multi-spectral digital camera to structure sampling
NDVI is the Normalized Difference Vegetation Index
Images are 20 cm x 20 cm plots in a polar desert ecosystem
NDVI
0.0 0.2 0.4 0.6 0.80.0
0.2
0.4
0.6
0.8
NDVI
0.2 0.4 0.6 0.80.0
0.2
0.4
0.6
0.0
0.2
0.4
0.6
0.8
. D integrifolia. S arctica
NDVInpvs = 0.21)a
)b
wr = 0.98
R2 = 0.82
-Canopy level
observedestimated
New tool: non-destructive measurements of the leaf area index
Steltzer and Welker (2006) Ecology
Experimental manipulations of climate and other global changes
Alpine tundra
Polar desert
Time since agriculture ceased (yr)
three eight nineteen0
200
400
600
800
1000
1200
Time since agriculture ceased (yr)
three eight nineteen0
200
400
600
800
1000between plantsunder plants
300
400
500
600
700
800
900
1000
1100
3
69
1215
18
0.20.3
0.4
Plant cover as a continuous variable
Phenological variation NDVI vs day of year
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
130 140 150 160 170 180 190 200 210 220 230 240 250 260
Day of Year
NDVI
Snow MeltLines are different years, data was collected using a near surface multi-band radiation sensor
Data from Barrow, AK; Huemmrich et al
Environmental sensor networks
• An LED pyranometer for $20
• Can be converted to measure NDVI or other vegetation indexes
Needs
• Variables of interest– Vegetation and soils– Microbial communities, biological diversity– Direct and indirect assessment
• models
• Instrumentation– Sensors– Platforms– Sensor networks
• Data– Automated analysis of imagery– Bioinformatics/data management
Acknowledgements
• National Science Foundation– Office of Polar Programs
• Tetracam Inc.• Joe DeCant• Jeff Welker• Rich Conant• Fred Hummerich and
other Specnetters• Seth Munson• NREL
