Research Papers

Impact of multiangular information on empirical models to estimate canopy nitrogen concentration in mixed forest

[+] Author Affiliations
Silvia Huber

University of Copenhagen, Department of Geography and Geology, Øster Voldgade 10, Copenhagen, Copenhagen 1350 Denmark

Benjamin Koetz

ESA/ESRIN, Via Galileo Galilei, CP 64, Frascati, 00044 Italy

Achilleas Psomas

Swiss Federal Research Institute WSL, Land Use Dynamics, Zu¨rcherstrasse 111, Birmensdorf, 8903 8057 Switzerland

Mathias Kneubuehler, Juerg T. Schopfer, Klaus I. Itten

University of Zurich, Department of Geography, Remote Sensing Laboratories, Winterthurerstrasse 190, Zurich, 8057 Switzerland

Niklaus E. Zimmermann

Swiss Federal Research Institute WSL, Land Use Dynamics, Zu¨rcherstrasse 111, Birmensdorf, 8903 8057 Switzerland

J. Appl. Remote Sens. 4(1), 043530 (May 7, 2010). doi:10.1117/1.3435334
History: Received May 9, 2007; Revised March 7, 2010; Accepted April 19, 2010; May 7, 2010; Online May 07, 2010
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Abstract

Directional effects in remotely sensed reflectance data can influence the retrieval of plant biophysical and biochemical estimates. Previous studies have demonstrated that directional measurements contain added information that may increase the accuracy of estimated plant structural parameters. Because accurate biochemistry mapping is linked to vegetation structure, also models to estimate canopy nitrogen concentration (CN) may be improved indirectly from using multiangular data. Hyperspectral imagery with five different viewing zenith angles was acquired by the spaceborne CHRIS sensor over a forest study site in Switzerland. Fifteen canopy reflectance spectra corresponding to subplots of field-sampled trees were extracted from the preprocessed CHRIS images and subsequently two-term models were developed by regressing CN on four datasets comprising either original or continuum-removed reflectances. Consideration is given to the directional sensitivity of the CN estimation by generating regression models based on various combinations (n=15) of observation angles. The results of this study show that estimating canopy CN with only nadir data is not optimal irrespective of spectral data processing. Moreover adding multiangular information improves significantly the regression model fits and thus the retrieval of forest canopy biochemistry. These findings support the potential of multiangular Earth observations also for application-oriented ecological monitoring.

© 2010 Society of Photo-Optical Instrumentation Engineers

Topics

Nitrogen

Citation

Silvia Huber ; Benjamin Koetz ; Achilleas Psomas ; Mathias Kneubuehler ; Juerg T. Schopfer, et al.
"Impact of multiangular information on empirical models to estimate canopy nitrogen concentration in mixed forest", J. Appl. Remote Sens. 4(1), 043530 (May 7, 2010). ; http://dx.doi.org/10.1117/1.3435334


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Plant nitrogen nutrition: sensing and signaling. Curr Opin Plant Biol Published online Jun 11, 2017;
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