Buffelgrass Phenology Project:
When and Where Buffelgrass is Green
Phenology Week Talk
October 3, 2014
Cynthia Wallace
Research Geographer, U.S. Geological Survey, Tucson AZ
Thanks to all of our Partners!
Phenology Days Celebration
www.usanpn.org/nn/phenoweek2014
The Sonoran Desert
Ecosystem
Wide spacing between individual plants
means that fires that start do not spread
Natural fires are
infrequent and of
low intensity
Credit: Caroline Patrick-Birdwell
Buffelgrass (Pennisetum ciliare) invasion
in the foothills of the Santa Catalina Mts.
north of Tucson
Credit: Caroline Patrick-Birdwell
Get it while it’s Green: Using MODIS satellite data
to capture dynamics of buffelgrass (Pennisetum
ciliare) phenology for eradication and management
USGS science and funds directed toward NPS management issue
Working with Saguaro National Park
Coupling field-based observation of buffelgrass phenology with
satellite “land surface phenology” and climate
Model when and where buffelgrass is green
Alert managers in a timely manner to treat optimally with herbicides
Data
MODIS Satellite Data
Buffelgrass Phenology Observations
SNP Mapping of Buffelgrass
Climate Data
Preliminary Results
Next Steps
Data
MODIS Satellite Data
Buffelgrass Phenology Observations
SNP Mapping of Buffelgrass
Climate Data
Preliminary Results
Next Steps
Passive Sensors
A passive sensor
records reflected or
emitted energy. Usually,
the energy source is the
sun.
Examples include aerial
and satellite images.
Note: Photographs and
image data are different.
Photos are recorded on
sensitized film whereas
images are recorded as
electronic data.
From: Shane Brandt, Geospatial Extension Agent, U of New Hampshire
Digital Format & Brightness Values
Pixel:
Sensor:
1m
IKONOS
1m
Quickbird
30 m
TM, ETM+
250 m MODIS
1 km
AVHRR
Canada Center for Remote Sensing
Digital format: the subdivision of an image into small equal-sized and
shaped areas, called picture elements or pixels, and representing the
brightness of each area with a numeric value or digital number.
1 2 3
4
TM Bands
5
7
50
Soil
40
Vegetation
30
20
Basalt
10
0.4
B
0.6
G R
0.8
1.0
NIR
1.4
1.6
Red (0.66 um)
1.8
SWIR
2.0
2.2
T
$
 Energy
2.4 um
Near Infrared (0.83 um)
DATA
Green (0.56 um)
1.2
Dark ---------------- Bright
ENERGY
Percent Reflectance
HowComposing
a Satellite
a Satellite ImageImage is Made
 Data
DISPLAY
Blue Gun
Green Gun
Red Gun
 Display
TM Bands
5
Dark ---------------- Bright
4
7
50
40
30
20
10
Soil
0.4
B
0.6
0.8
1.0
G R
NIR
T
$
Vegetation
NIR band
Percent Reflectance
1 2 3
Red band
Green band
Blue band
ENERGY
Composing a Satellite Image
Energy
Basalt
1.2
1.4
1.6
1.8
SWIR
2.0
2.2
2.4 um
A band of an image is the measurements taken in a
specific region of the electromagnetic spectrum.
TA
Green (0.56 um)
Red (0.66 um)
Near Infrared (0.83 um)
0.4
B
0.6
0.8
1.0
G R
NIR
1.2
1.4
1.6
1.8
SWIR
2.0
2.2
2.4 um
Data (from 3 bands of energy)
Red (0.66 um)
Near Infrared (0.83 um)
DATA
Green (0.56 um)
Blue Gun
Green Gun
Red Gun
DISPLAY
In this case, we are creating a “false color” composite, where by
convention, green band energy is assigned the color blue, red band
energy is assigned the color green, and near infrared energy (which is
directly undetectable by the human eye) is assigned the color red,
Display – a “False Color Composite”
DISPLAY
Blue Gun
Green Gun
Red Gun
Near-IR (band 4) Red (band 3) Green (band 2) Blue (band 1)
S
A
T
E
L
L
I
T
E
C
O
M
P
U
T
E
R
From: Shane Brandt, U of New Hampshire
TM Bands
5
Dark ---------------- Bright
4
7
50
40
30
20
10
Soil
0.4
B
0.6
0.8
1.0
G R
NIR
T
$
Vegetation
NIR band
Percent Reflectance
1 2 3
Red band
Green band
Blue band
ENERGY
Composing
a Satellite Image
Spectral
Signature
Basalt
1.2
1.4
1.6
1.8
SWIR
2.0
2.2
2.4 um
The pattern of reflectance characteristic of a surface.
Vegetation has a distinctive spectral signature.
TA
Green (0.56 um)
Red (0.66 um)
Near Infrared (0.83 um)
Plant Phenology and Spectral
Response – One Species
(From: Jensen, John R. Remote Sensing of the
Environment: An Earth Resource Perspective.)
• Chlorophyll in green leaves absorbs blue and
red, reflects green and NIR
• Senescent leaves reflect more red, less NIR
• Band ratio can distinguish actively
photosynthesizing vegetation from senescent
• Observing seasonal patterns can identify
plant species, guide management decisions
Vegetation Indices
For example:
Normalized Difference Vegetation Index
NDVI = (NIR - Red)/(NIR + Red)
V.I.s are Remote sensing surrogates for
estimating certain biophysical parameters of
plants (e.g., percent cover, biomass, LAI)
From: Paul Pinter,USDA, ARS, US Water Conservation Laboratory
Data
MODIS Satellite Data
Buffelgrass Phenology Observations
SNP Mapping of Buffelgrass
Climate Data
Preliminary Results
Next Steps
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Ventana Trail Site
Ventana Waterfall Site
Ventana Mist Site
Areas in red outline patches of dense buffelgrass from 2008 aerial
mapping of the western Santa Catalina foothills area of Tucson AZ.
Data
MODIS Satellite Data
Buffelgrass Phenology Observations
SNP Mapping of Buffelgrass
Climate Data
Preliminary Results
Next Steps
Saguaro National Park
The spatial pattern of rainfall is highly variable in the Sonoran Desert
Photo Credit: Zack Guido, CLIMAS, The University of Arizona
Data
MODIS Satellite Data
Buffelgrass Phenology Observations
SNP Mapping of Buffelgrass
Climate Data
Preliminary Results
Next Steps
Get it while it’s Green: Preliminary Results
3000
2800
2600
2400
2200
2000
1800
1600
1400
1200
1000
2011
2012
90.00
2013
80.00
70.00
60.00
50.00
40.00
MODIS-EVI
30.00
Pct_green
20.00
10.00
90.0
2011
80.0
2012
13-22
13-19
13-16
13-13
13-10
13-07
13-04
13-01
12-21
12-18
12-15
12-12
12-09
12-06
12-03
11-23
11-20
11-17
11-14
11-11
11-08
11-05
11-02
10-22
10-19
10-16
10-13
0.00
3.5
2013
3
70.0
2.5
60.0
50.0
2
40.0
1.5
30.0
1
20.0
Pct_green
PPT Total (in)
0.5
10.0
13-22
13-19
13-16
13-13
13-10
13-07
13-04
13-01
12-21
12-18
12-15
12-12
12-09
12-06
12-03
11-23
11-20
11-17
11-14
11-11
11-08
11-05
11-02
10-22
10-19
10-16
0
10-13
0.0
Observed buffelgrass greenness, MODIS-EVI and Precipitation (PPT) data for 16-day periods
Get it while it’s Green: Statistical correlation analysis
Fourier Harmonics of Annual Phenology
Temporal NDVI profiles for selected SE Arizona landscapes
1998
Forest
Shrubland
Grassland
1999
Wetland
Forest
Shrubland
Grassland
Fourier Harmonic Analysis of a Waveform
Wetland
AZ phenometrics for 1998
Get it while it’s Green: Harmonics analysis of each variable by year
2011
•
•
MODIS and Greenness patterns align
PPT pattern precedes Greenness
Get it while it’s Green: Harmonics analysis comparing variables
•
Timing of PPT always earlier, Timing of Greenness and MODIS typically coincide
Preliminary Results
Buffelgrass greenness observed on the ground is strongly
correlated to contemporaneous MODIS-EVI greenness.
Buffelgrass greenness observed on the ground is highly correlated
to precipitation of the prior time-period and the prior two time
periods (prior 16 day total and prior 32 day total).
Annual harmonics resonance between greenness-MODIS-PPT
show consistent patterns, with PPT peaks preceding others and
with greenness and MODIS in synchronicity.
Saguaro National Park: so far, we have found lower MODIS-EVI
values for some vegetation types with buffelgrass invasion vs.
areas without buffelgrass.
Data
MODIS Satellite Data
Buffelgrass Phenology Observations
SNP Mapping of Buffelgrass
Climate Data
Preliminary Results
Next Steps
MODIS NDVI Profiles
Precipitation (UA Station)
5
2002
4
3
2
1
0
1
2
3
4
5
6
7
2002 (7.47")
8
9
10
11
12
11
12
Ave(11.28")
5
4
2005
3
2
1
0
1
2
3
4
5
6
2005 (11.55")
7
8
9
10
Ave(11.28")
How to participate…..
1. Join Nature’s Notebook
2. Find a site to monitor buffelgrass – Choose a location that you
will visit once every week or two. I can help you select a site or
you can have your own site added to the network.
3. Sign up as an observer – Become an official participant with
Nature’s Notebook and set your username and password. All
you need is an email address and Internet access. When you
are registering, identify yourself as part of this effort by
selecting “Buffelgrass Monitoring Network, Tucson” from the
Partner Organization drop-down menu.
Thank you!