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The Forest
Changescape:
a view from above
Daniel J. Hayes
ORNL Environmental Science Division
SAMSI - Program on Mathematical
and Statistical Ecology (ECOL)
Workshop
Wednesday, 20 August 2014
Research Triangle Park, NC
What is a “changescape”?
Credit: Joe Hughes (image) and Doug Kaylor (term coinage)
A Spatiotemporal Perspective on 30 Years of
Forest Change as Viewed from Space
Dan Hayes, Joe Hughes, Doug
Kaylor, and Virginia Dale –
Oak Ridge National Laboratory
and the University of
Tennessee
Jeff Masek – NASA Goddard
Space Flight Center
Robert Kennedy and Warren
Cohen – US Forest Service and
Oregon State University
A Spatiotemporal Perspective on 30 Years of
Forest Change as Viewed from Space
Outline
• Forest disturbance ecology
– Ecosystem services
– Characteristics of disturbance
– Vulnerability / Resilience
• Remote Sensing & Change Detection
– Discrete date comparison
– Trend analysis
• New Methods
• The Eastern U.S. Forest Changescape
• Challenges and Opportunities
– Methods
– Applications
Forest Ecosystem Services
All over the world,
society depends on critical ecosystem services provided by forests.
Source: The Millennium Ecosystem Assessment (2005)
Forest Dynamics
Change
is ubiquitous and unceasing in forest ecosystems and landscapes
Source: USDA Forest Service, Southern Research Station
Landscape
Region
Continent
“Pulse”
Disturbances
Local
Spatial Scale of Impact
Adapted from Bender et al. (1984),
Peterson et al. (1998) and Dale et al. (1998)
Characteristics of Disturbance
CLIMATE CHANGE
PERMAFROST THAW
DROUGHT
HURRICANES
INVASIVES
INSECT
OUTBREAKS
FIRE
DISEASE
DEFORESTATION
LOGGING
WINDTHROW
Abrupt
Gradual
Temporal Scale of Impact
“Press”
Disturbances
Continent
Region
Landscape
Local
PERMAFROST THAW
DROUGHT
HURRICANES
INVASIVES
INSECT
OUTBREAKS
FIRE
Anthropogenic
Spatial Scale of Impact
CLIMATE CHANGE
Natural
Adapted from Bender et al. (1984),
Peterson et al. (1998) and Dale et al. (1998)
Characteristics of Disturbance
DISEASE
DEFORESTATION
LOGGING
WINDTHROW
Abrupt
Gradual
Temporal Scale of Impact
Continent
Region
Landscape
Local
PERMAFROST THAW
DROUGHT
HURRICANES
INVASIVES
INSECT
OUTBREAKS
FIRE
Anthropogenic
Spatial Scale of Impact
CLIMATE CHANGE
Natural
Adapted from Bender et al. (1984),
Peterson et al. (1998) and Dale et al. (1998)
Disturbance Interactions
DISEASE
DEFORESTATION
LOGGING
WINDTHROW
Abrupt
Gradual
Temporal Scale of Impact
Vulnerability / Resiliency of Forests
Dale et al. (2001) BioScience
Shifts in disturbance regime
outside the normal range of
variability?
Dale, Hughes and Hayes (in review)
nps.gov
Bill de Groot, NR-Can
A continental tour
of “natural” (or
indirectly
anthropogenic)
disturbances…
for.gov.bc.ca
maineforestry.net
ucanr.edu
NASA / J. Chambers
D. Kaylor, UTK
Alberta Geological Survey
A continental tour
of anthropogenic
disturbances…
Bangor Daily News
Google Earth
NASA / Tom Sever
Vivian Stockman, OVEC • 2003
Remote Sensing of Forest Disturbances
Change Detection Techniques
• Up to 2009:
– Discrete comparison (differencing, thresholding, classification, etc.)
between each specific image (airphoto or satellite) acquisition date
(two or more years)
• Since 2009:
– Trend analysis over a more full and continuous archive of satellite
imagery
Remote Sensing of Forest Disturbances
Large and severe “pulse” disturbance (deforestation) on Landsat imagery
Hayes and Sader (2001) PERS
Remote Sensing of Forest Disturbances
Large and severe “pulse” disturbance (clear-cutting) on Landsat imagery
Cohen et al. (2002) Ecosystems
Remote Sensing of Forest Disturbances
Trends in disturbance and recovery:
exploiting the full historical Landsat archive
Kennedy et al. (2010) RSE
Methods: Image acquisition
•
Trends in disturbance and recovery:
exploiting the full historical Landsat
archive
What do you do
with this stuff??
Landsat Thematic Mapper
• 30m spatial resolution (per
pixel)
• 6 spectral bands
(wavelength ranges)
• Repeat observations every
16 days
• Coverage since 1972 (moreor-less)
• Full archive freely available
(since 2009)
Methods: Pre-processing
Summer clear-sky composite (aka cloud removal)
Hughes and Hayes (2014) Remote Sensing
Methods: Vegetation Indices
Landsat spectral bands
Hughes and Hayes (2014) Remote Sensing
Methods: Vegetation Indices
Normalized Difference Vegetation Index (NDVI)
(NIR – Red)/(NIR + Red)
(Band4 – Band3)/(Band4 + Band3)
Methods: Trend Analysis
Vegetation Index (Single Pixel Through Time)
Hughes and Hayes (2014) Remote Sensing
Results: Spatial patterns of severity
Methods: Validation
Cohen et al. (2010) RSE
Vegetation Index
Hughes and Hayes (2014) Remote Sensing
Results: Broad-scale patterns
Monitoring rates of disturbance:
the North American Forest Dynamics project
Goward et al.; Masek et al.
Can we detect more subtle trends?
• Stress-related decline?
Source:
Warren Cohen
Results: Beyond the single pixel
Disturbance Increases Patch Variance in Vegetation Index
Hughes et al. in prep
Methods: Patch Identification
Vegetation Index – “Patch-ified”: TVR
Hughes et al. in prep
Hughes and Hayes (2014) Remote Sensing
Remote Sensing of Forest Disturbances
Can we distinguish between different disturbance agents?
USFS Areal Insect and Disease Survey (IDS)
Remote Sensing of Forest Disturbances
Can we distinguish between different disturbance agents?
USFS Areal Insect and Disease Survey (IDS)
Results: Patch Variance
Agents Distinguished by Patch Variance
Hughes et al. in prep
Methods: Scales of Disturbance
Vegetation Index – “Patch-ified”
α = 0.20
α = 0.05
Hughes et al. in prep
Hughes and Hayes (2014) Remote Sensing
α = 0.02
Methods: Automated Classification
Training a neural network
Hughes et al. in prep
Results: Spatial Patterns
Results: Validation
Evaluation and Analysis
Hughes et al. in prep
Results: Temporal Patterns
% of area affected
Southern
Pine Beetle
Results: Regional Patterns
Southern
Pine Beetle
Gypsy Moth
Beech Bark
Disease
Hemlock
Wooly
Adelgid
Fire
TOTAL
Future Directions
• The method
– More “truth”: testing / validation
– Model parameter sensitivity (e.g. α in TVR)
– Train for anthropogenic agents (land use change)
• The analysis
– First comprehensive reports, statistics and maps of
disturbance (by time, space, severity & agent) for
eastern U.S.
– Conservation (protected areas) and management
Future Directions
• The applications
– Impacts of climate change, pollution, etc. on
vegetation productivity (both increases and
declines)
– Impacts of disturbance on the forest carbon sink
– Detection of thaw-driven landscape change in
permafrost ecosystems (Arctic Tundra and Boreal
Forest)
Thank You!
Dan Hayes
[email protected]
Oak Ridge National Laboratory:
Meeting the challenges of the 21st century
www.ornl.gov