Exploring the potential of transmittance vegetation indices for leaf functional traits retrieval

Leaf functional traits are key indicators of plant functions useful for inferring complex plant processes, including their responses to environmental changes. Vegetation indices (VIs) composed of a few reflectance wavelengths hold the advantages of being relatively simple and effective and have been...

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Main Authors: Yuwen Chen, Jia Sun, Lunche Wang, Shuo Shi, Feng Qiu, Wei Gong, Shaoqiang Wang, Torbern Tagesson
Format: Article
Language:English
Published: Taylor & Francis Group 2023-12-01
Series:GIScience & Remote Sensing
Subjects:
Online Access:http://dx.doi.org/10.1080/15481603.2023.2168410
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author Yuwen Chen
Jia Sun
Lunche Wang
Shuo Shi
Feng Qiu
Wei Gong
Shaoqiang Wang
Torbern Tagesson
author_facet Yuwen Chen
Jia Sun
Lunche Wang
Shuo Shi
Feng Qiu
Wei Gong
Shaoqiang Wang
Torbern Tagesson
author_sort Yuwen Chen
collection DOAJ
description Leaf functional traits are key indicators of plant functions useful for inferring complex plant processes, including their responses to environmental changes. Vegetation indices (VIs) composed of a few reflectance wavelengths hold the advantages of being relatively simple and effective and have been widely used within remote sensing to estimate leaf traits. However, the difference between the reflectance from the upper and lower part of the leaf suggests that leaf reflectance mainly provides one-sided information, constraining its ability to estimate leaf functional traits. Leaf transmittance, on the other hand, gives information about the whole leaf and has more potential to be sensitive to changes in leaf biochemistry. As transmittance-based VI is rare, this study aims to propose new transmittance-based VIs for accurate estimations of leaf traits. Three forms, i.e. the normalized difference VI, the simple ratio VI, and the difference VI were employed, and wavelength selection for transmittance-based and reflectance-based VIs were conducted, respectively. The applicability of these VIs for estimating four leaf functional traits (leaf chlorophyll (Cab), leaf carotenoids (Car), equivalent water thickness (EWT), and leaf mass per area (LMA)) were evaluated. Cross-validation using three datasets of field observations and sensitivity analysis showed that the VIs constructed using transmittance were relatively less affected by interferences from other leaf parameters, improving the estimation accuracy of Car, EWT, and LMA compared to their optimal reflectance counterparts (RMSE reduced by 2% to 15%, and MAE reduced by 7% to 20% for the pooled dataset). Our study revealed that the normalized difference VI based on transmittance showed considerable sensitivity to Car, EWT, and LMA, whereas the difference VI based on reflectance was effective in indicating Cab. The proposed transmittance-based VIs will aid remote monitoring of leaf traits and thereby plant adaptations and acclimation to changes in environmental conditions.
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spelling doaj.art-d127b0625120493f8a84f72292191ec12023-09-21T12:43:09ZengTaylor & Francis GroupGIScience & Remote Sensing1548-16031943-72262023-12-0160110.1080/15481603.2023.21684102168410Exploring the potential of transmittance vegetation indices for leaf functional traits retrievalYuwen Chen0Jia Sun1Lunche Wang2Shuo Shi3Feng Qiu4Wei Gong5Shaoqiang Wang6Torbern Tagesson7China University of GeosciencesChina University of GeosciencesChina University of GeosciencesWuhan UniversityNanjing UniversityWuhan UniversityChina University of GeosciencesLund UniversityLeaf functional traits are key indicators of plant functions useful for inferring complex plant processes, including their responses to environmental changes. Vegetation indices (VIs) composed of a few reflectance wavelengths hold the advantages of being relatively simple and effective and have been widely used within remote sensing to estimate leaf traits. However, the difference between the reflectance from the upper and lower part of the leaf suggests that leaf reflectance mainly provides one-sided information, constraining its ability to estimate leaf functional traits. Leaf transmittance, on the other hand, gives information about the whole leaf and has more potential to be sensitive to changes in leaf biochemistry. As transmittance-based VI is rare, this study aims to propose new transmittance-based VIs for accurate estimations of leaf traits. Three forms, i.e. the normalized difference VI, the simple ratio VI, and the difference VI were employed, and wavelength selection for transmittance-based and reflectance-based VIs were conducted, respectively. The applicability of these VIs for estimating four leaf functional traits (leaf chlorophyll (Cab), leaf carotenoids (Car), equivalent water thickness (EWT), and leaf mass per area (LMA)) were evaluated. Cross-validation using three datasets of field observations and sensitivity analysis showed that the VIs constructed using transmittance were relatively less affected by interferences from other leaf parameters, improving the estimation accuracy of Car, EWT, and LMA compared to their optimal reflectance counterparts (RMSE reduced by 2% to 15%, and MAE reduced by 7% to 20% for the pooled dataset). Our study revealed that the normalized difference VI based on transmittance showed considerable sensitivity to Car, EWT, and LMA, whereas the difference VI based on reflectance was effective in indicating Cab. The proposed transmittance-based VIs will aid remote monitoring of leaf traits and thereby plant adaptations and acclimation to changes in environmental conditions.http://dx.doi.org/10.1080/15481603.2023.2168410leaf transmittanceremote sensingwavelength selectionsensitivity analysis
spellingShingle Yuwen Chen
Jia Sun
Lunche Wang
Shuo Shi
Feng Qiu
Wei Gong
Shaoqiang Wang
Torbern Tagesson
Exploring the potential of transmittance vegetation indices for leaf functional traits retrieval
GIScience & Remote Sensing
leaf transmittance
remote sensing
wavelength selection
sensitivity analysis
title Exploring the potential of transmittance vegetation indices for leaf functional traits retrieval
title_full Exploring the potential of transmittance vegetation indices for leaf functional traits retrieval
title_fullStr Exploring the potential of transmittance vegetation indices for leaf functional traits retrieval
title_full_unstemmed Exploring the potential of transmittance vegetation indices for leaf functional traits retrieval
title_short Exploring the potential of transmittance vegetation indices for leaf functional traits retrieval
title_sort exploring the potential of transmittance vegetation indices for leaf functional traits retrieval
topic leaf transmittance
remote sensing
wavelength selection
sensitivity analysis
url http://dx.doi.org/10.1080/15481603.2023.2168410
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