2013 asprs track, monitoring ponderosa pine health using satellite imagery by kathleen johnson
DESCRIPTION
In recent years, forested areas along the foothills of the Colorado Front Range have been subject to parasite infestations and drought conditions that have stressed these systems. The focus of this study are the Ponderosa Pines (Pinus ponderosa) of the Jefferson County Parks and Open Space, which show the accumulated effects of infestation by Dwarf Mistletoe (Arceuthobium vaginatum cryptopodum), Mountain Pine Beetle (Dendroctonus ponderosae), and drought conditions that began in the Fall of 2011. Numerous studies have demonstrated the effectiveness of satellite imagery analysis for the monitoring of parasite infestations and general forest health. We have examined WorldView-2 satellite imagery from 2010-2013, confirmed by ground truth provided by Jefferson County Parks and Open Space for White Ranch Park and Elk Meadow Park. The research approach included the examination of data optimization methods for spectral identification of affected trees using 8-band data (e.g., normalized band ratios, principal component analysis, maximum noise fraction, and statistical validation), decision tree land cover classification methods, and change detection. The results of supervised classification analysis of Ponderosa Pine health have an accuracy of > 90% and a precision of 0.89 (Kappa Statistic). High accuracy land cover mapping is critical for parasite mitigation, and efforts to minimize future infestations. This project is part of an ongoing a partnership between Jefferson County Parks and Open Space and DigitalGlobe, monitoring vegetation health, invasive species and parasite activity for the purpose of long-range remediation planning.TRANSCRIPT
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Monitoring Ponderosa Pine Health Using Satellite Imagery
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DigitalGlobe 2
• Kathleen Johnson*
• Greg Hammann
• Rachana Ravi
• Keith Bol
• Barbara Morey
Monitoring Ponderosa Pine Health Using Satellite Imagery
Team Participants:
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Goals & Objectives
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• To Demonstrate the capabilities of WV02 8-bands for vegetation health/stress assessments
• Document the extent of tree stress from 2010 through 2013 in the White Ranch Park Area, using satellite imagery.
• Test Case for DG classification system applied to vegetative health studies
• Look for evidence of new Mountain Pine Beetle Activity
DigitalGlobe
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World View-2
DigitalGlobe
TABLE 1: WorldView -2 Bands
Band
#
Name Wavelength
(nm)
1 Coastal 400-450
2 Blue 450-510
3 Green 510-580
4 Yellow 585-625
5 Red 630-690
6 Red Edge 705-745
7 NIR1 770-895
8 NIR2 860-1040
PAN Panchromatic 450-800
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Jefferson County Preliminary Study: Elk Meadow Park
5 DigitalGlobe
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Elk Meadow: Dwarf Mistletoe Damage
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False Color: Healthy Trees are Bright Red
Natural Color: Damage is Visible
DigitalGlobe
JUNE 2010 JUNE 2012
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Jefferson County Research Site: White Ranch Park
7 DigitalGlobe
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Ground Truth Assumptions:
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•Ground Truth for Dwarf Mistletoe acquired December 2010 (Rawhide and Sawmill Ridges)
• Treatment for mistletoe control started after ground truth acquisition (Spring 2011-Present)
•Mountain Pine Beetle was discovered during the Winter Survey in 2010, and treatment began at that time.
DigitalGlobe
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White Ranch Park: Ground Truth
9 DigitalGlobe
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Parasites:
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Dwarf Mistletoe (Arceuthobium vaginatum)
Mountain Pine Beetle (Dendroctonus ponderosae)
DigitalGlobe
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Pre-Processing:
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• Imagery Selection (4): - 10JUNE24, 11AUGUST23, 12MAY24, 13AUGUST14
•Bundle Adjustment -Orthorectification (30 m DEM)
-Co-registration
•Atmospheric Correction (DG-ACOMP)
DigitalGlobe
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Normalized Difference Vegetation Index (NDVI)
NDVI = (rNIR – rRED)/(rNIR + rRED) Brightness = Health
Vegetative Indices
DigitalGlobe
TABLE 4. Summary of Vegetative Indices applied to the JCOS Forestry Problem
Index Formula Bands Reference
Normalized Difference
Vegetative Index NIR1 NDVI-1
(NIR1 - Red)/(NIR1 + Red)
7-5 Rouse et al. (1974)
Shamsodinni et al. (2010)
Normalized Difference
Vegetative Index NIR2 NDVI-2
(NIR2 - Red)/(NIR2 + Red)
8-5 Rouse et al. (1974)
Shamsodinni et al. (2010)
Red Edge NDVI (Red Edge - Red)/(Red Edge + Red) 6-5 Filchev (2010)
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JUNE 2010 AUGUST 2013 CHANGE
NDVI Results & Change Detection
DigitalGlobe
Table 7. Change Detection Color Codes
BLUE Negative Change:
YELLOW Neutral/Positive Change:
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Classification Model:
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•DG Classification-Supervised
•Decision Tree Classifiers: • Robust to outliers
• Applies the same rule at each Node
• Compares well to Non-linear Classifiers
• Random Forest – Ensemble Tree Method • (Random Forest: Breiman 2001)
•Use WEKA Scorer to Evaluate Models • http://www.cs.waikato.ac.nz/ml/weka/
DigitalGlobe
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Random Forest – 20 Trees:
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•A stable model builder with little data preprocessing
•Does not require a normal distribution
• Relies upon balanced class sample size
• Ensemble decision tree method (employs multiple trees)
•Most robust decision tree method for outliers
• Competitive with nonlinear classifiers such as neural networks
DigitalGlobe
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Classification Results: Accuracy and Precision
DigitalGlobe
Imagery Accuracy Kappa Statistic
10JUNE24 93.17 0.92
11AUG23 93.47 0.92
12MAY24 93.88 0.93
13AUG14 89.69 0.88
95% Confidence Interval
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Ponderosa Health: Random Forest-20
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10JUNE24 11AUGUST23
DigitalGlobe
Table 8. Classification Codes
ORANGE Unhealthy/Stressed
GREEN Healthy
Yellow-Green Broadleaf
12MAY24 13AUGUST14
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Ponderosa Health: Random Forest-20
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10JUNE24 11AUGUST23
DigitalGlobe
Table 8. Classification Codes
ORANGE Unhealthy/Stressed
GREEN Healthy
Yellow-Green Broadleaf
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Ponderosa Health: Random Forest-20
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12MAY24 13AUGUST14
DigitalGlobe
Table 8. Classification Codes
ORANGE Unhealthy/Stressed
GREEN Healthy
Yellow-Green Broadleaf
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Ponderosa Health: Pine Beetle Treatment
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10JUNE24 11AUGUST23
DigitalGlobe
Table 8. Classification Codes
ORANGE Unhealthy/Stressed
GREEN Healthy
Yellow-Green Broadleaf
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Ponderosa Health: Pine Beetle Treatment
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12MAY24 13AUGUST14
DigitalGlobe
Table 8. Classification Codes
ORANGE Unhealthy/Stressed
GREEN Healthy
Yellow-Green Broadleaf
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DigitalGlobe 22
Summary of Classification Results
10JUNE24 11AUGUST23 12MAY241 3AUGUST14
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Conclusions:
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• Ponderosa Pines within White Ranch Park have shown signs of accumulated stress: - Mistletoe,
- Pine Beetle
- Drought (Fa11 2011-Spring 2013)
- Tree stress was severe enough to be visible in natural color imagery in many instances.
- Through time, the total number of trees has been reduced by remediation activities
• DG Classification results were more reliable than NDVI Change Detection: - Performed at > 90% accuracy except in the case of the 2013, where some of
the ground truth had been removed by mistletoe remediation.
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Conclusions:
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• This Study lays the foundation for continuing forestry studies across the Foot Hills region, using satellite imagery:
- Identify additional areas to be examined for mistletoe infestation and
remediation
- Can identify potential Pine Beetle attacks early IF we can capture imagery during the proper stages of the Life Cycle (need March snow free imagery)
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Acknowledgments:
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• JCOS: Keith Bol, Barbara Morey
• Project Sponsor: Kumar Navulur, NGP Director
• My Manager: Giovanni Marchisio, Data Mining Director
• DG Classification Training: Rachana Ravi, Kris Koperski
• Data Pre-Processing: Chuck Chaapel, Donnie Marino
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Thank You Questions/Discussion