Vegetation stress detection through chlorophyll a + b estimation and fluorescence effects on hyperspectral imagery.

Physical principles applied to remote sensing data are key to successfully quantifying vegetation physiological condition from the study of the light interaction with the canopy under observation. We used the fluorescence-reflectance-transmittance (FRT) and PROSPECT leaf models to simulate reflectance as a function of leaf biochemical and fluorescence variables. A series of laboratory measurements of spectral reflectance at leaf and canopy levels and a modeling study were conducted, demonstrating that effects of chlorophyll fluorescence (CF) can be detected by remote sensing. The coupled FRT and PROSPECT model enabled CF and chlorophyll a + b (Ca + b) content to be estimated by inversion. Laboratory measurements of leaf reflectance (r) and transmittance (t) from leaves with constant Ca + b allowed the study of CF effects on specific fluorescence-sensitive indices calculated in the Photosystem I (PS-I) and Photosystem II (PS-II) optical region, such as the curvature index [CUR; (R675.R690)/R2(683)]. Dark-adapted and steady-state fluorescence measurements, such as the ratio of variable to maximal fluorescence (Fv/Fm), steady state maximal fluorescence (F'm), steady state fluorescence (Ft), and the effective quantum yield (delta F/F'm) are accurately estimated by inverting the FRT-PROSPECT model. A double peak in the derivative reflectance (DR) was related to increased CF and Ca + b concentration. These results were consistent with imagery collected with a compact airborne spectrographic imager (CASI) sensor from sites of sugar maple (Acer saccharum Marshall) of high and low stress conditions, showing a double peak on canopy derivative reflectance in the red-edge spectral region. We developed a derivative chlorophyll index (DCI; calculated as D705/D722), a function of the combined effects of CF and Ca + b content, and used it to detect vegetation stress.

[1]  George Papageorgiou,et al.  6 – Chlorophyll Fluorescence: An Intrinsic Probe of Photosynthesis , 1975 .

[2]  W. Verhoef.  Light scattering by leaf layers with application to canopy reflectance modelling: The SAIL model , 1984 .

[3]  W. Bilger,et al.  Rapid assessment of stress effects on plant leaves by chlorophyll fluorescence measurements , 1987 .

[4]  Hartmut K. Lichtenthaler,et al.  The Role of Chlorophyll Fluorescence in The Detection of Stress Conditions in Plants , 1988 .

[5]  B. Rock,et al.  Comparison of in situ and airborne spectral measurements of the blue shift associated with forest decline , 1988 .

[6]  F. Baret,et al.  PROSPECT: A model of leaf optical properties spectra , 1990 .

[7]  F. Stuart Chapin,et al.  Integrated Responses of Plants to Stress , 1991 .

[8]  K. LichtenthalerH,et al.  The Kautsky effect: 60 years of chlorophyll fluorescence induction kinetics. , 1992 .

[9]  D. M. Moss,et al.  Red edge spectral measurements from sugar maple leaves , 1993 .

[10]  G. Carter.  Ratios of leaf reflectances in narrow wavebands as indicators of plant stress , 1994 .

[11]  G. Mohammed,et al.  Chlorophyll fluorescence: A review of its practical forestry applications and instrumentation , 1995 .

[12]  I. Filella,et al.  Reflectance assessment of mite effects on apple trees , 1995 .

[13]  A. Gitelson,et al.  Signature Analysis of Leaf Reflectance Spectra: Algorithm Development for Remote Sensing of Chlorophyll , 1996 .

[14]  John R. Miller,et al.  Atmospheric Correction Validation of casi Images Acquired over the Boreas Southern Study Area , 1997 .

[15]  J. Peñuelas,et al.  Photochemical reflectance index and leaf photosynthetic radiation-use-efficiency assessment in Mediterranean trees , 1997 .

[16]  J. Gamon,et al.  The photochemical reflectance index: an optical indicator of photosynthetic radiation use efficiency across species, functional types, and nutrient levels , 1997, Oecologia.

[17]  Josep Peñuelas,et al.  Comparative field study of spring and summer leaf gas exchange and photobiology of the mediterranean trees Quercus ilex and Phillyrea latifolia , 1998 .

[18]  John A. Gamon,et al.  Assessing leaf pigment content and activity with a reflectometer , 1999 .

[19]  S. Colombo,et al.  Does Canadian forestry need physiology research , 1999 .

[20]  Hartmut K. Lichtenthaler,et al.  The Chlorophyll Fluorescence Ratio F735/F700 as an Accurate Measure of the Chlorophyll Content in Plants , 1999 .

[21]  Pablo J. Zarco-Tejada,et al.  Hyperspectral Remote Sensing of Closed Forest Canopies: Estimation of Chlorophyll Fluorescence and Pigment Content , 2000 .

[22]  Pablo J. Zarco-Tejada,et al.  The Bioindicators of Forest Condition Project: a physiological, remote sensing approach. , 2000 .

[23]  Pablo J. Zarco-Tejada,et al.  Chlorophyll fluorescence effects on vegetation apparent reflectance: II. laboratory and airborne canopy-level measurements with hyperspectral data. , 2000 .

[24]  Pablo J. Zarco-Tejada,et al.  Chlorophyll Fluorescence Effects on Vegetation Apparent Reflectance: I. Leaf-Level Measurements and Model Simulation , 2000 .

[25]  John R. Miller,et al.  Scaling-up and model inversion methods with narrowband optical indices for chlorophyll content estimation in closed forest canopies with hyperspectral data , 2001, IEEE Trans. Geosci. Remote. Sens..

[26]  Pablo J. Zarco-Tejada,et al.  ESTIMATION OF CHLOROPHYLL FLUORESCENCE UNDER NATURAL ILLUMINATION FROM HYPERSPECTRAL DATA , 2001 .

[27]  G. Krause,et al.  Chlorophyll fluorescence as a tool in plant physiology , 1984, Photosynthesis Research.