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Challenges of monitoring natural disturbance processes using remotely sensed data in North Coast and Cascades Network: comparison of approaches. Natalya Antonova , NCCN Catharine Thompson, NCCN Robert Kennedy, OSU*. LandTrendr slides provided by Robert Kennedy. NCCN Monitoring Goals. - PowerPoint PPT Presentation
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Challenges of monitoring natural disturbance processes using
remotely sensed data in North Coast and Cascades Network:
comparison of approaches
Natalya Antonova, NCCNCatharine Thompson, NCCN
Robert Kennedy, OSU*
LandTrendr slides provided by Robert Kennedy
NCCN Monitoring Goals
• Document landscape changes• When, where, what and magnitude
• Status and trends• Prepare for and manage for landscape responses
to climate change• Develop prediction tools
• Test hypotheses
NCCN Monitoring Goals
Monitoring goal Type 1: Monitor yearly Avalanche chute clearing
Landslides Fire Insect/disease defoliation in forest Windthrow Riparian disturbance Clearcuts Rural development
Type 2: Monitor decadally Alpine tree encroachment
Hardwood/conifer forest composition Forest structure
Protocol for Landsat-Based Monitoring of Landscape Dynamics at NCCN Parks – Kennedy et al.
1. Two different images
2. Select large changes in spectral values to indicate change
Subtract
1994 2004
Probabilities of Change
Brightness: RedGreenness: GreenWetness: Blue
Brt+Grn: Yellow/OrangeBrt+Wet: MagentaGrn+Wet: Cyan
Tasseled-cap transformation of Landsat image
Astoria
Snow and iceMixed
Open: Dark
Water/Deep shade
Closed-canopy coniferDense broadleaf/
grassBroadleaf tree/shrub
Conifer/Broad-leaf Mix
Increasing TC Brightness
Incr
easi
ng
TC
Gre
enn
ess
Open: Bright
Change in Probability of Membership
Time 1
Time 2
Probability Thresholding
All spectral changesAll spectral changes
ArtifactsArtifacts
Uninteresting* changeUninteresting* change
Real changeReal change
Sensor degradation, atmospheric contamination,
geometric misregistration, sun angle variation
Sensor degradation, atmospheric contamination,
geometric misregistration, sun angle variation
Seasonality of vegetation (phenology), clouds, agricultural practices
Seasonality of vegetation (phenology), clouds, agricultural practices
Sustained change in land cover or
condition
Sustained change in land cover or
condition
Mapped “change”Mapped “change”Mapped “no-change” Mapped “no-change” Th
resh
old
Thre
shol
d
FALSE POSITIVESFALSE POSITIVES
FALSE NEGATIVESFALSE NEGATIVES
North Cascades National Park
Complex
July 29, 2005-Aug 17, 2006
Mount Rainier
National Park
Aug 14, 2005-Aug 17, 2006
Olympic National Park
July 24, 2004-June 28, 2006
Validation - Errors of Omissiona) b)
c) d)
e)
TC 2005 TC 2006
Change image
2006 NAIP Aerial Photo
Polygons outlined in the validation process compared to change detected by the algorithm
Validation - Errors of Commissiona) b)
c) d)
e)
TC 2005 TC 2006
Changeimage
Polygons outlined in the validation process compared to change detected by the algorithm
Change image from east side of the study area
125 m
Subalpine Environments, Avalanche Chutes, Tree line, and River Disturbances
2004
2006
Increase in conifer Increase in broadleaf Increase in vegetation Decrease in conifer
Summary: Current Protocol
• Can detect change• Detected too much false change (clouds, shadows,
agricultural dynamics) to provide meaningful results
• Threshold level not sensitive enough to detect annual regrowth or low intensity, slow disturbance
• Difficult to see change along narrow, long features of interest, due to misregistration errors
• Upper elevation areas appear as pure speckle due to variable landcover and annual variation in phenology
Landsat-based Detection of Trends in Disturbance and Recovery (LandTrendr)
Rather than look for disturbance EVENTS, look for disturbance TRAJECTORIES
Kennedy, R.E., Cohen, W.B., & Schroeder, T.A. (2007). Trajectory-based change detection for automated characterization of forest disturbance dynamics. Remote Sensing of Environment, 110, 370-386
Segmentation
• Goodness of fit to idealized curves
• Allows for lower threshold levels
• Greatly reduces amount of background noise
Cloud/Shadow Screening
CloudCloud Shadow CloudCloud Shadow
Merge
Poor-quality Images
19961996 1998199819971997
Olympic Peninsula Olympic Peninsula
Outputs
Disturbance and recovery maps
• Intensity/Magnitude• Year of onset• Duration
Current protocol vs. LandTrendr
Original protocol detected ~100,00 ha of change between 2004 and 2006 within the OLYM study area
Current protocol vs. LandTrendr
∑ = ~ 30,000 ha
LandTrendr – Clearcuts: Forestlands north of Cle Elum, WA
20+ yr20+ yr
10+ yr starting 1990s10+ yr starting 1990s
RecentRecent
LandTrendr - Insect disease/defoliation: Olimpic N.P.
LandTrendr - Avalanches
LandTrendr –Windthrow
LandTrendr - Fire
LandTrendr - Landslides
LandTrendr- Pros
• Captures Pacific Northwest landscape dynamics well
• Captures smaller changes that are still of interest• Already has long time series
• 25 years of change• Provides additional products like intensity and
regeneration• Includes Canada• Works for small and large parks
LandTrendr - Cons
• Expensive to implement• Still need to interpret results (ascribe agent of
change)• Develop methodology
Subsampling? Modeling? Validate every polygon in park?
• Developed for forested areas • results have not been evaluated for subalpine
vegetation
Existing Tools: C-CAP Data
• NOAA- Coastal Change Analysis Program • Classified Landsat TM data• Every five years (1996, 2001, 2006 …)• Products:
• Map of 21 classes• Map of change between classes
• Accuracy of change classes varies between 75 and 95%• Focus on coastal areas
High Intensity DevelopedMedium Intensity DevelopedLow Intensity DevelopedDeveloped Open Space
CultivatedPasture/Hay
GrasslandDeciduous ForestEvergreen ForestMixed ForestScrub/ShrubBare LandWaterSnow/Ice
Palustrine Emergent WetlandPalustrine Forested WetlandPalustrine Scrub/Shrub WetlandEstuarine Emergent Wetland
Unconsolidated ShorePalustrine Aquatic BedEstuarine Aquatic Bed
C-CAP Data Analysis - Example from SAJH
C-CAP vs. LandTrendr
C-CAP vs. LandTrendr (acres)Landtrendr CCAP
OLYM_AOI 22933.34 69735.51OLYM 1733.72 79.62
MORA_AOI 10273.08 14581.35MORA 1294.99 11.88
NOCA_AOI 6807.26 6735.60NOCA 914.92 42.21
C-CAP vs. LandTrender – Rural Development
C-CAP vs. LandTrender - Fire
C-CAP vs. Landtrendr - Riparian
C-CAP -Pros• Free• Simple analysis to get results• Could provide “big picture” change detection
outside park, particularly reductions in forest cover
C-CAP - Cons
• Misses certain change types Slow increase or decrease in vegetation, narrow
features like riparian• Accuracy unknown, errors propagate• Long time delay for results (01-06 change
available in 09)• 5 year interval too long for some types of
change Rivers, avalanche chutes
• No control over product• Doesn’t cover Canada• Still need to ascribe agent to change
Current Efforts
•Automatically assign disturbance agent based on:• Trajectory label• Location on
landscape• Proximity to stream• Aspect• Elevation• Geology• Soil Type