Mapping forest and site quality of planted Chinese fir forest using sentinel images

Normally, forest quality (FQ) and site quality (SQ) play an important role in evaluating actual and potential forest productivity. Traditionally, these assessment indices (FQ and SQ) are mainly based on forest parameters extracted from ground measurement (forest height, age, density, forest stem vol...

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Main Authors: Chongjian Tang, Zilin Ye, Jiangping Long, Zhaohua Liu, Tingchen Zhang, Xiaodong Xu, Hui Lin
Format: Article
Language:English
Published: Frontiers Media S.A. 2022-10-01
Series:Frontiers in Plant Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fpls.2022.949598/full
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author Chongjian Tang
Chongjian Tang
Chongjian Tang
Zilin Ye
Zilin Ye
Jiangping Long
Jiangping Long
Jiangping Long
Zhaohua Liu
Zhaohua Liu
Zhaohua Liu
Tingchen Zhang
Tingchen Zhang
Xiaodong Xu
Xiaodong Xu
Xiaodong Xu
Hui Lin
Hui Lin
Hui Lin
author_facet Chongjian Tang
Chongjian Tang
Chongjian Tang
Zilin Ye
Zilin Ye
Jiangping Long
Jiangping Long
Jiangping Long
Zhaohua Liu
Zhaohua Liu
Zhaohua Liu
Tingchen Zhang
Tingchen Zhang
Xiaodong Xu
Xiaodong Xu
Xiaodong Xu
Hui Lin
Hui Lin
Hui Lin
author_sort Chongjian Tang
collection DOAJ
description Normally, forest quality (FQ) and site quality (SQ) play an important role in evaluating actual and potential forest productivity. Traditionally, these assessment indices (FQ and SQ) are mainly based on forest parameters extracted from ground measurement (forest height, age, density, forest stem volume (FSV), and DBH), which is labor-intensive and difficult to access in certain remote forest areas. Recently, remote sensing images combined with a small number of samples were gradually applied to map forest parameters because of the various advantages of remote sensing technology, such as low cost, spatial coverage, and high efficiency. However, FQ and SQ related to forest parameters are rarely estimated using remote sensing images and machine learning models. In this study, the Sentinel images and ground samples of planted Chinese fir forest located in the ecological “green-core” area of Changzhutan urban cluster, were initially employed to explore the feasibility of mapping the FQ and SQ. And then, four types of alternative variables (backscattering coefficients (VV and VH), multi-spectral bands, vegetation indices, and texture characteristics) were extracted from Sentinel-1A and Sentinel-2A images, respectively. After selecting variables using a stepwise regression model, three machine learning models (SVR, RF, and KNN) were employed to estimate various forest parameters. Finally, the FQ of the study region was directly mapped by the weights sum of related factors extracted by the factor analysis method, and the SQ was also extracted using mapped forest height and age. The results illustrated that the accuracy of estimated forest parameters (DBH, H, and Age) was significantly higher than FSV, FCC, and Age and the largest and smallest rRMSEs were observed from FSV (0.38~0.40) and forest height (0.20~0.21), respectively. Using mapped forest parameters, it also resulted that the rRMSEs of estimated FQ and SQ were 0.19 and 0.15, respectively. Furthermore, after normalization and grading, the grades of forest quality were mainly concentrated in grades I, II, and III in the study region. Though the accuracy of mapping FQ and SQ is limited by the saturation phenomenon, it is significantly proved that using machine learning models and Sentinel images has great potential to indirectly map FQ and SQ.
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spelling doaj.art-6073c66bbb3a47f8884bc4813a0408c92022-12-22T03:49:30ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2022-10-011310.3389/fpls.2022.949598949598Mapping forest and site quality of planted Chinese fir forest using sentinel imagesChongjian Tang0Chongjian Tang1Chongjian Tang2Zilin Ye3Zilin Ye4Jiangping Long5Jiangping Long6Jiangping Long7Zhaohua Liu8Zhaohua Liu9Zhaohua Liu10Tingchen Zhang11Tingchen Zhang12Xiaodong Xu13Xiaodong Xu14Xiaodong Xu15Hui Lin16Hui Lin17Hui Lin18Research Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Changsha, ChinaKey Laboratory of Forestry Remote Sensing Based Big Data & Ecological Security for Hunan Province, Changsha, ChinaKey Laboratory of State Forestry Administration on Forest Resources Management and Monitoring in Southern Area, Changsha, ChinaResearch Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Changsha, ChinaKey Laboratory of Forestry Remote Sensing Based Big Data & Ecological Security for Hunan Province, Changsha, ChinaResearch Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Changsha, ChinaKey Laboratory of Forestry Remote Sensing Based Big Data & Ecological Security for Hunan Province, Changsha, ChinaKey Laboratory of State Forestry Administration on Forest Resources Management and Monitoring in Southern Area, Changsha, ChinaResearch Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Changsha, ChinaKey Laboratory of Forestry Remote Sensing Based Big Data & Ecological Security for Hunan Province, Changsha, ChinaKey Laboratory of State Forestry Administration on Forest Resources Management and Monitoring in Southern Area, Changsha, ChinaResearch Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Changsha, ChinaKey Laboratory of Forestry Remote Sensing Based Big Data & Ecological Security for Hunan Province, Changsha, ChinaResearch Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Changsha, ChinaKey Laboratory of Forestry Remote Sensing Based Big Data & Ecological Security for Hunan Province, Changsha, ChinaKey Laboratory of State Forestry Administration on Forest Resources Management and Monitoring in Southern Area, Changsha, ChinaResearch Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Changsha, ChinaKey Laboratory of Forestry Remote Sensing Based Big Data & Ecological Security for Hunan Province, Changsha, ChinaKey Laboratory of State Forestry Administration on Forest Resources Management and Monitoring in Southern Area, Changsha, ChinaNormally, forest quality (FQ) and site quality (SQ) play an important role in evaluating actual and potential forest productivity. Traditionally, these assessment indices (FQ and SQ) are mainly based on forest parameters extracted from ground measurement (forest height, age, density, forest stem volume (FSV), and DBH), which is labor-intensive and difficult to access in certain remote forest areas. Recently, remote sensing images combined with a small number of samples were gradually applied to map forest parameters because of the various advantages of remote sensing technology, such as low cost, spatial coverage, and high efficiency. However, FQ and SQ related to forest parameters are rarely estimated using remote sensing images and machine learning models. In this study, the Sentinel images and ground samples of planted Chinese fir forest located in the ecological “green-core” area of Changzhutan urban cluster, were initially employed to explore the feasibility of mapping the FQ and SQ. And then, four types of alternative variables (backscattering coefficients (VV and VH), multi-spectral bands, vegetation indices, and texture characteristics) were extracted from Sentinel-1A and Sentinel-2A images, respectively. After selecting variables using a stepwise regression model, three machine learning models (SVR, RF, and KNN) were employed to estimate various forest parameters. Finally, the FQ of the study region was directly mapped by the weights sum of related factors extracted by the factor analysis method, and the SQ was also extracted using mapped forest height and age. The results illustrated that the accuracy of estimated forest parameters (DBH, H, and Age) was significantly higher than FSV, FCC, and Age and the largest and smallest rRMSEs were observed from FSV (0.38~0.40) and forest height (0.20~0.21), respectively. Using mapped forest parameters, it also resulted that the rRMSEs of estimated FQ and SQ were 0.19 and 0.15, respectively. Furthermore, after normalization and grading, the grades of forest quality were mainly concentrated in grades I, II, and III in the study region. Though the accuracy of mapping FQ and SQ is limited by the saturation phenomenon, it is significantly proved that using machine learning models and Sentinel images has great potential to indirectly map FQ and SQ.https://www.frontiersin.org/articles/10.3389/fpls.2022.949598/fullplanted Chinese fir forestforest qualitysite qualitymachine learningsentinel
spellingShingle Chongjian Tang
Chongjian Tang
Chongjian Tang
Zilin Ye
Zilin Ye
Jiangping Long
Jiangping Long
Jiangping Long
Zhaohua Liu
Zhaohua Liu
Zhaohua Liu
Tingchen Zhang
Tingchen Zhang
Xiaodong Xu
Xiaodong Xu
Xiaodong Xu
Hui Lin
Hui Lin
Hui Lin
Mapping forest and site quality of planted Chinese fir forest using sentinel images
Frontiers in Plant Science
planted Chinese fir forest
forest quality
site quality
machine learning
sentinel
title Mapping forest and site quality of planted Chinese fir forest using sentinel images
title_full Mapping forest and site quality of planted Chinese fir forest using sentinel images
title_fullStr Mapping forest and site quality of planted Chinese fir forest using sentinel images
title_full_unstemmed Mapping forest and site quality of planted Chinese fir forest using sentinel images
title_short Mapping forest and site quality of planted Chinese fir forest using sentinel images
title_sort mapping forest and site quality of planted chinese fir forest using sentinel images
topic planted Chinese fir forest
forest quality
site quality
machine learning
sentinel
url https://www.frontiersin.org/articles/10.3389/fpls.2022.949598/full
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