Hyperspectral discrimination of tropical rain forest tree species at leaf to crown scales

Hyperspectral discrimination of tropical dry forest lianas and trees: Comparative data reduction approaches at the leaf and canopy levels

“…For separating liana from tree leaves, the top ten bands for discrimination were dominated by the visible (3 bands) and the shortwave infrared (6 wavebands), with the near infrared region being less important (1 band) in contrast to the canopy level for which the top ten wavebands were from the shortwave infrared (Table 2). Our results contrast with those presented by Clark et al (2005) when comparing wavelengths, which in the case of Clark et al (2005) was aimed to separate among leaves of different tropical wet forest species. Clark et al (2005) found that nine of the top ten significant wavebands were in the near infrared and mid-infrared regions; areas where they found large variations in the absolute reflectance values.…”

“…Our results contrast with those presented by Clark et al (2005) when comparing wavelengths, which in the case of Clark et al (2005) was aimed to separate among leaves of different tropical wet forest species. Clark et al (2005) found that nine of the top ten significant wavebands were in the near infrared and mid-infrared regions; areas where they found large variations in the absolute reflectance values. A possible explanation for these differences is that chlorophyll and other pigments vary more than photon scattering in the internal cellular structures between tree and liana leaves, whereas the opposite may be true for discriminating leaves of different tree species.…”

“…Cochrane, 2000;Castro et al, 2006;Lee & Graham, 1986;Lee et al, 1990) and from airborne imagery (Clark et al, 2005;Zhang et al, in press). The body of literature focusing on the spectral properties and separability of lianas from trees is scarce in comparison CastroEsau et al, 2004).…”

Mesoscale assessment of changes in tropical tree species richness across a bioclimatic gradient in Panama using airborne imaging spectroscopy

“…Since the airborne data were collected during the early dry season many dry forest drought deciduous trees occur in leaf-off conditions exposing more bark, epiphytes and dry background to the sensor; components all showing relatively high VIS reflectance (Clark & Roberts, 2012;Somers, Verbesselt, et al, 2010;Toomey, Roberts, & Nelson, 2009). In addition, many dry forest tree species flower in the dry season (Wright & Van Schaik, 1994) again adding to the VIS reflectance variability (flowers have high VIS reflectance; Clark et al, 2005). Another remarkable observation was that differences in NIR reflectance between the dry site and the wet and moist sites were relatively small (SI N 15), which could indicate that on average canopy structure and LAI were comparable.…”

“…The measured reflectance spectra are sensitive to the structural organization of, and variations in chemical constituents in, canopy components. These physico-chemical-tospectral linkages provide a means of detecting species and/or functional types (e.g., Asner & Vitousek, 2005;Clark, Roberts, & Clark, 2005;Somers & Asner, 2012;Ustin & Gamon, 2010), and can even provide information about the biogeochemical heterogeneity (e.g. Townsend, Asner, & Cleveland, 2008;Vitousek, Asner, Chadwick, & Hotchkiss, 2009) and species richness of tropical forest canopies (e.g., Asner, Nepstad, Cardinot, & Ray, 2004;Carlson, Asner, Hughes, Ostertag, & Martin, 2007;Feret & Asner, 2013;Kalacska et al, 2007;Nagendra & Rocchini, 2008;Somers and Asner, 2013).…”