Red edge shift and biochemical content in grass canopies

Onisimo Mutanga*, Andrew K. Skidmore

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

180 Citations (Scopus)

Abstract

The concentration of foliar nitrogen in tropical grass is one of the factors that explain the distribution of wildlife. Therefore, the remote sensing of foliar nitrogen contributes to a better understanding of wildlife feeding patterns. This study evaluated changes in the red edge position of the 680 nm continuum removed chlorophyll feature in the reflectance spectra of samples of Cenchus ciliaris grass grown in a greenhouse under three levels of nitrogen supply. Canopy spectral measurements from each treatment were recorded under controlled laboratory conditions over a four-week period using a GER 3700 spectroradiometer. Results indicate that the mean wavelength positions of the three fertilization treatments were statistically different. An increase in nitrogen supply yielded a shift in the red edge position to longer wavelengths. The red edge position, amplitude, slope at 713 nm and slope at 725 nm were significantly correlated to measured nitrogen concentration (bootstrapped r = 0.89, - 0.28, 0.63 and 0.75, respectively) even at canopy level. Based on these results, the red edge position is strongly correlated with biochemical concentration in plants compared to the other methods tested. The study provides conclusive evidence that confirms the strength of a red edge-nitrogen relationship that remains underused in remote sensing. This method is promising for estimating nutrient content in grasslands.

Original languageEnglish
Pages (from-to)34-42
Number of pages9
JournalISPRS Journal of Photogrammetry and Remote Sensing
Volume62
Issue number1
DOIs
Publication statusPublished - May 2007
Externally publishedYes

Keywords

  • bootstrapping
  • chlorophyll absorption feature
  • continuum removal
  • nitrogen concentration
  • red edge position

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