Separating physiologically and directionally induced changes in PRI using BRDF models

Hilker, Thomas; Coops, Nicholas C.; Hall, Forrest G.; Black, T. Andrew; Wulder, Michael A.; Nesic, Zoran; Krishnan, P.

doi:10.1016/j.rse.2008.01.011

Cited by 170 publications

(167 citation statements)

References 58 publications

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“…Detailed models of PRI, which include a description of the geometry and discontinuity of canopy and different depth penetrations of light into the canopy, are developed on the basis of these models [109,137,138]. Also, linear and nonlinear regressions are widely used to describe the connection between PRI and photosynthetic parameters [62,76,124,137,139].…”

Section: Resultsmentioning

confidence: 99%

Connection of the Photochemical Reflectance Index (PRI) with the Photosystem II Quantum Yield and Nonphotochemical Quenching Can Be Dependent on Variations of Photosynthetic Parameters among Investigated Plants: A Meta-Analysis

Sukhova

Sukhov

2018

Remote Sensing

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Abstract:The development of spectral methods of remote sensing, including measurement of a photochemical reflectance index (PRI), is a prospective trend in precision agriculture. There are many works which have investigated the connection between photosynthetic parameters and PRI; however, their results varied and were sometimes contradictory. For this paper, we performed a meta-analysis of works in this field. Here, only linear correlations of PRI with photosynthetic parameters-including quantum yield of photosystem II (∆F/Fm'), nonphotochemical quenching of chlorophyll fluorescence (NPQ), and light use efficiency (LUE)-were investigated. First, it was shown that the correlations were dependent on conditions of PRI measurements (leaf or canopy; artificial light or sunlight). Second, it was shown that a minimal level of the photosynthetic stress, and the variation of this level among investigated plants, can influence the linear correlation of PRI with ∆F/Fm' and NPQ; the effect was dependent on conditions of measurements. In contrast, the distribution of LUE among plants did not influence its correlation with PRI. Thus, the meta-analysis shows that the distribution of photosynthetic parameters among investigated plants can be an important factor that influences the efficiency of remote sensing on the basis of the PRI measurement.

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Section: Resultsmentioning

confidence: 99%

Connection of the Photochemical Reflectance Index (PRI) with the Photosystem II Quantum Yield and Nonphotochemical Quenching Can Be Dependent on Variations of Photosynthetic Parameters among Investigated Plants: A Meta-Analysis

Sukhova

Sukhov

2018

Remote Sensing

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“…The multi-angular observations obtained from AMSPEC could be used to parameterize PROSAIL directly; however, individual stand-level measurements taken under different view angles and from different portions of the canopy are not necessarily representative of stand-level conditions as they observe varying proportions of non-photosynthetic background. A better praxis to infer stand-level data from AMSPEC is to model the bidirectional reflectance distribution function (BRDF) from multi-angular observations observed in all directions around the tower during short time intervals for which canopy level pigment content is approximately constant (Hilker et al 2008). One BRDF model can then be established for each time interval and stand level reflectance can be inferred for any sun-observer geometry based on all observations taken during this period.…”

Section: Inversion Of the Prosail Canopy Modelmentioning

confidence: 99%

“…Finally, the status of the xanthophyll cycle pigments was determined using multi-angular observations of the photochemical reflectance index (PRI) (Gamon et al 1992(Gamon et al , 1993Hilker et al 2008)…”

Section: Use Of Vegetation Indices For Estimation Of Stand Level Pigmmentioning

confidence: 99%

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Tracking plant physiological properties from multi-angular tower-based remote sensing

et al. 2011

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Imaging spectroscopy is a powerful technique for monitoring the biochemical constituents of vegetation and is critical for understanding the fluxes of carbon and water between the land surface and the atmosphere. However, spectral observations are subject to the sunobserver geometry and canopy structure which impose confounding effects on spectral estimates of leaf pigments. For instance, the sun-observer geometry influences the spectral brightness measured by the sensor. Likewise, when considering pigment distribution at the stand level scale, the pigment content observed from single view angles may not necessarily be representative of stand-level conditions as some constituents vary as a function of the degree of leaf illumination and are therefore not isotropic. As an alternative to mono-angle observations, multi-angular remote sensing can describe the anisotropy of surface reflectance and yield accurate information on canopy structure. These observations can also be used to describe the bi-directional reflectance distribution which then allows the modeling of reflectance independently of the observation geometry. In this paper, we demonstrate a method for estimating pigment contents of chlorophyll and carotenoids continuously over a year from tower-based, multi-angular spectro-radiometer observations. Estimates of chlorophyll and carotenoid content were derived at two flux-tower sites in western Canada. Pigment contents derived from inversion of a CR model (PROSAIL) compared well to those estimated using a semi-analytical approach (r 2 = 0.90 and r 2 = 0.69, P \ 0.05 for both sites, respectively). Analysis of the seasonal dynamics indicated that net ecosystem productivity was strongly related to total canopy chlorophyll content at the deciduous site (r 2 = 0.70, P \ 0.001), but not at the coniferous site. Similarly, spectral estimates of photosynthetic light-use efficiency showed strong seasonal patterns in the deciduous stand, but not in conifers. We conclude that multi-angular, spectral observations can play a key role in explaining seasonal dynamics of fluxes of carbon and water and provide a valuable addition to fluxtower-based networks.

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“…Different viewing geometries are also taken into account as long as the locations of both the camera and the sun are known. The separation of an individual tree canopy into illuminated and shaded parts has been done before in Leaf Area Index (LAI), Normalized Difference Vegetation Index (NDVI) and canopy radiative transfer studies [19][20][21]. This approach has been utilised in single tree species classification as well [22,23].…”

Section: Tree Canopy Division Into Illuminated and Shaded Partsmentioning

confidence: 99%

Individual Tree Species Classification by Illuminated—Shaded Area Separation

2009

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Abstract:A new method, called Illumination Dependent Colour Channels (IDCC), is presented to improve individual tree species classification. The method is based on tree crown division into illuminated and shaded parts on a digital aerial image. Colour values of both sides of the tree crown are then used in species classification. Tree crown division is achieved by comparing the projected location of an aerial image pixel with its neighbours on a Canopy Height Model (CHM), which is calculated from a synchronized LIDAR point cloud. The sun position together with the mapping aircraft position are also utilised in illumination status detection. The new method was tested on a dataset of 295 trees and the classification results were compared with ones measured with two other feature extraction methods. The results of the developed method gave a clear improvement in overall tree species classification accuracy.

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Separating physiologically and directionally induced changes in PRI using BRDF models

Cited by 170 publications

References 58 publications

Connection of the Photochemical Reflectance Index (PRI) with the Photosystem II Quantum Yield and Nonphotochemical Quenching Can Be Dependent on Variations of Photosynthetic Parameters among Investigated Plants: A Meta-Analysis

Connection of the Photochemical Reflectance Index (PRI) with the Photosystem II Quantum Yield and Nonphotochemical Quenching Can Be Dependent on Variations of Photosynthetic Parameters among Investigated Plants: A Meta-Analysis

Tracking plant physiological properties from multi-angular tower-based remote sensing

Individual Tree Species Classification by Illuminated—Shaded Area Separation

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