Invasive species detection in Hawaiian rainforests using airborne imaging spectroscopy and LiDAR

Gregory P. Asner, David E. Knapp, Ty Kennedy-Bowdoin, Matthew O. Jones, Roberta E. Martin, Joseph Boardman, R. Flint Hughes

Research output: Contribution to journalArticlepeer-review

132 Scopus citations

Abstract

Remote sensing of invasive species is a critical component of conservation and management efforts, but reliable methods for the detection of invaders have not been widely established. In Hawaiian forests, we recently found that invasive trees often have hyperspectral signatures unique from that of native trees, but mapping based on spectral reflectance properties alone is confounded by issues of canopy senescence and mortality, intra- and inter-canopy gaps and shadowing, and terrain variability. We deployed a new hybrid airborne system combining the Carnegie Airborne Observatory (CAO) small-footprint light detection and ranging (LiDAR) system with the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) to map the three-dimensional spectral and structural properties of Hawaiian forests. The CAO-AVIRIS systems and data were fully integrated using in-flight and post-flight fusion techniques, facilitating an analysis of forest canopy properties to determine the presence and abundance of three highly invasive tree species in Hawaiian rainforests. The LiDAR sub-system was used to model forest canopy height and top-of-canopy surfaces; these structural data allowed for automated masking of forest gaps, intra- and inter-canopy shadows, and minimum vegetation height in the AVIRIS images. The remaining sunlit canopy spectra were analyzed using spatially-constrained spectral mixture analysis. The results of the combined LiDAR-spectroscopic analysis highlighted the location and fractional abundance of each invasive tree species throughout the rainforest sites. Field validation studies demonstrated < 6.8% and < 18.6% error rates in the detection of invasive tree species at ∼ 7 m2 and ∼ 2 m2 minimum canopy cover thresholds. Our results show that full integration of imaging spectroscopy and LiDAR measurements provides enormous flexibility and analytical potential for studies of terrestrial ecosystems and the species contained within them.

Original languageEnglish (US)
Pages (from-to)1942-1955
Number of pages14
JournalRemote Sensing of Environment
Volume112
Issue number5
DOIs
StatePublished - May 15 2008
Externally publishedYes

Keywords

  • AVIRIS
  • Airborne Visible and Infrared Imaging Spectrometer
  • CAO
  • Carnegie Airborne Observatory
  • Hawaii
  • Invasive species
  • Light detection and ranging
  • Tropical forest

ASJC Scopus subject areas

  • Soil Science
  • Geology
  • Computers in Earth Sciences

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