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A LandTrendr multispectral ensemble for forest disturbance detection

Author(s):

Zhiqiang Yang
Robert E. Kennedy
Noel Gorelick

Year:

2018

Publication type:

Scientific Journal (JRNL)

Primary Station(s):

Pacific Northwest Research Station

Source:

Remote Sensing of Environment. 205: 131-140.

Description

Monitoring and classifying forest disturbance using Landsat time series has improved greatly over the past decade, with many new algorithms taking advantage of the high-quality, cost free data in the archive. Much of the innovation has been focused on use of sophisticated workflows that consist of a logical sequence of processes and rules, multiple statistical functions, and parameter sets that must be calibrated to accurately classify disturbance. For many algorithms, calibration has been local to areas of interest and the algorithm's classification performance has been good under those circumstances. When applied elsewhere, however, algorithm performance has suffered. An alternative strategy for calibration may be to use the locally tested parameter values in conjunction with a statistical approach (e.g., Random Forests; RF) to align algorithm classification with a reference disturbance dataset, a process we call secondary classification. We tested that strategy here using RF with LandTrendr, an algorithm that runs on one spectral band or index. Disturbance detection using secondary classification was spectral band- or index-dependent, with each spectral dimension providing some unique detections and different error rates. Using secondary classification, we tested whether an integrated multispectral LandTrendr ensemble, with various combinations of the six basic Landsat reflectance bands and seven common spectral indices, improves algorithm performance. Results indicated a substantial reduction in errors relative to secondary classification based on single bands/indices, revealing the importance of a multispectral approach to forest disturbance detection. To explain the importance of specific bands and spectral indices in the multispectral ensemble, we developed a disturbance signal-to-noise metric that clearly highlighted the value of shortwaveinfrared reflectance, especially when paired with near-infrared reflectance.

Citation

Cohen, Warren B.; Yang, Zhiqiang; Healey, Sean P.; Kennedy, Robert E.; Gorelick, Noel. 2018. A LandTrendr multispectral ensemble for forest disturbance detection. Remote Sensing of Environment. 205: 131-140.

Cited

Publication Notes

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  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
https://www.fs.usda.gov/treesearch/pubs/56396