Climbing the Spatial Ladder: Mapping Tree Mortality with Global Satellite Imagery
Travis R. Cowles
Jeffrey A. Hicke
Arjan J. H. Meddens
University of Idaho
Moscow, ID
University of Idaho
Moscow, ID
University of Idaho
Moscow, ID
www.forestryimages.org 1. Project Justification
•  Bark beetles are important indicators of, and potenJal feedback agents to, climate change Ø Outbreaks correlate with regional episodes of warming and drought Ø Beetle life cycles are temperature dependent Ø Tree mortality events can affect local and regional biogeophysical and biogeochemical processes, leading to effects on future climate •  Recent bark beetle outbreaks have occurred in many areas previously believed to be unsuitable Ø  High elevaJon Ø  High laJtude boreal forests •  Aerial surveys are the most spaJally comprehensive system of bark beetle detecJon but have disadvantages for broad scale analyses Ø  SpaJally incomplete o  Typically no coverage in wilderness areas or naJonal parks Ø  SubjecJve data collecJon of “affected area” or number of trees killed •  No conJnental to global scale objecJve measurement of beetle-­‐caused tree mortality currently exists •  Remote sensing provides the opportunity to objecJvely measure bark beetle-­‐caused tree mortality at local to global scales •  MODerate ResoluJon Imaging Spectroradiometer (MODIS) imagery offers the potenJal to map tree mortality at regional to global scales based on its spaJal, spectral, and temporal characterisJcs 5. MODIS-Based Tree
Mortality Detection
in Northern CO
2. Project Goals
•  Develop MODIS based algorithms of bark beetle-­‐caused tree mortality over northern CO •  Create annual maps of tree mortality compared with the historical record of ADS for western North America in the MODIS era (2000-­‐present) Central Colorado MODIS image 2008 following a bark beetle outbreak 3. Data and methods
•  MODIS imagery datasets provide
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500-meter spatial resolution
Daily temporal resolution
7 spectral bands of data (visible-middle infrared)
Period of data collection: 2000 to present
Data available at no cost
•  Use Landsat tree mortality time series stack as training and
evaluation data (Meddens et al. in review)
•  Tree mortality algorithms to be developed:
Ø  Categorical classification using maximum likelihood and
classification and regression tree analysis
Ø  Continuous models of mortality using regression models and
spectral mixture analysis
4. Tree Mortality Detection with Remote Sensing
•  We have developed
methods to map tree
mortality using high
to medium resolution
imagery in northern
Colorado
Meddens et. al (2012) Ecological Applications •  Field observations
and higher resolution
imagery serve as
evaluation data for
coarser resolution
studies
•  High accuracies have
been achieved with 30cm aerial imagery
(88%, top) and 30-m
Landsat imagery (95%,
center)
Aerial Imagery (30 cm) Meddens et al. (2011) Remote Sensing of Environment Landsat (30 m) Meddens and Hicke (in review) Remote Sensing of Environment •  Preliminary analysis of
MODIS imagery
(bottom) displays
similar patterns of
mortality with overall
accuracies of 78%
MODIS (500 m) •  More rigorous
analyses are in
progress to better
describe tree mortality
in northern Colorado
Meddens et al. (2009) LANDFIRE Report 6. Acknowledgements
Support is provided by the USGS Western Mountain Initiative,
Los Alamos National Lab, and NSF EPSCoR.
7. References
Meddens et al. (2009) LANDFIRE Report Meddens, A. J. H., Hicke, J. A. (in review). EvaluaJng methods to detect bark beetle-­‐
caused tree mortality using single-­‐date and mulJ-­‐date Landsat imagery. Remote Sensing of Environment, SubmiLed: 20 July 2012 Meddens, A. J. H., et al. (2012). SpaJal and temporal paLerns of observed bark beetle-­‐
caused tree mortality in BriJsh Columbia and the western US. Ecological Applica5ons, Ecological Society of America. Meddens, A. J. H., et al. (2011). EvaluaJng the potenJal of mulJspectral imagery to map mulJple stages of tree mortality. Remote Sensing of Environment, 115(7), 1632-­‐1642. Meddens, A. J. H., et al. (2009). DetecJon of Beetle-­‐Caused Tree Mortality from Satellite Imagery for Use in the LANDFIRE Project: Methods Development and EvaluaJon. Report to the USGS/LANDFIRE, University of Idaho, 14 September 2009