Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests
Significant gaps exist in our knowledge of the impact of leaf aging on canopy signal variability, which limits our understanding of vegetation status based on remotely sensed data. To understand the effects of leaf aging at the leaf and canopy scales, a combination of field, remote-sensing and physi...
| Main Authors: | , , , , , |
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| Format: | Article |
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MDPI AG
2018-02-01
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| Series: | Remote Sensing |
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| Online Access: | http://www.mdpi.com/2072-4292/10/2/262 |
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| author | Qiaoli Wu Conghe Song Jinling Song Jindi Wang Shaoyuan Chen Bo Yu |
| author_facet | Qiaoli Wu Conghe Song Jinling Song Jindi Wang Shaoyuan Chen Bo Yu |
| author_sort | Qiaoli Wu |
| collection | DOAJ |
| description | Significant gaps exist in our knowledge of the impact of leaf aging on canopy signal variability, which limits our understanding of vegetation status based on remotely sensed data. To understand the effects of leaf aging at the leaf and canopy scales, a combination of field, remote-sensing and physical modeling techniques was adopted to assess the canopy spectral signals of evergreen Cunninghamia forests. We observed an approximately 10% increase in Near-Infrared (NIR) reflectance for new leaves and a 35% increase in NIR transmittance for mature leaves from May to October. When variations in leaf optical properties (LOPs) of only mature leaves, or both new and mature leaves were considered, the Geometric Optical and Radiative Transfer (GORT) model-simulated canopy reflectance trajectory was more consistent with Landsat observations (R2 increased from 0.37 to 0.82~0.89 for NIR reflectance, and from 0.35 to 0.67~0.88 for EVI2, with a small RMSE (0.01 to 0.02)). This study highlights the importance of leaf age on leaf spectral signatures, and provides evidence of age-dependent LOPs that have important impacts on canopy reflectance in the NIR band and EVI2, which are used to monitor canopy dynamics and productivity, with important implications for RS and forest ecosystem ecology. |
| first_indexed | 2024-12-20T11:21:18Z |
| format | Article |
| id | doaj.art-611ab30a0da942b9b3f7b8d02d721b1c |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-12-20T11:21:18Z |
| publishDate | 2018-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-611ab30a0da942b9b3f7b8d02d721b1c2022-12-21T19:42:30ZengMDPI AGRemote Sensing2072-42922018-02-0110226210.3390/rs10020262rs10020262Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir ForestsQiaoli Wu0Conghe Song1Jinling Song2Jindi Wang3Shaoyuan Chen4Bo Yu5State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences, Beijing 100875, ChinaDepartment of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USAState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences, Beijing 100875, ChinaState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences, Beijing 100875, ChinaState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences, Beijing 100875, ChinaState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences, Beijing 100875, ChinaSignificant gaps exist in our knowledge of the impact of leaf aging on canopy signal variability, which limits our understanding of vegetation status based on remotely sensed data. To understand the effects of leaf aging at the leaf and canopy scales, a combination of field, remote-sensing and physical modeling techniques was adopted to assess the canopy spectral signals of evergreen Cunninghamia forests. We observed an approximately 10% increase in Near-Infrared (NIR) reflectance for new leaves and a 35% increase in NIR transmittance for mature leaves from May to October. When variations in leaf optical properties (LOPs) of only mature leaves, or both new and mature leaves were considered, the Geometric Optical and Radiative Transfer (GORT) model-simulated canopy reflectance trajectory was more consistent with Landsat observations (R2 increased from 0.37 to 0.82~0.89 for NIR reflectance, and from 0.35 to 0.67~0.88 for EVI2, with a small RMSE (0.01 to 0.02)). This study highlights the importance of leaf age on leaf spectral signatures, and provides evidence of age-dependent LOPs that have important impacts on canopy reflectance in the NIR band and EVI2, which are used to monitor canopy dynamics and productivity, with important implications for RS and forest ecosystem ecology.http://www.mdpi.com/2072-4292/10/2/262leaf ageleaf spectral propertiesleaf area indexCunninghamiaChinese fircanopy reflectanceNIREVI2geometric optical radiative transfer (GORT) model |
| spellingShingle | Qiaoli Wu Conghe Song Jinling Song Jindi Wang Shaoyuan Chen Bo Yu Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests Remote Sensing leaf age leaf spectral properties leaf area index Cunninghamia Chinese fir canopy reflectance NIR EVI2 geometric optical radiative transfer (GORT) model |
| title | Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests |
| title_full | Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests |
| title_fullStr | Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests |
| title_full_unstemmed | Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests |
| title_short | Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests |
| title_sort | impacts of leaf age on canopy spectral signature variation in evergreen chinese fir forests |
| topic | leaf age leaf spectral properties leaf area index Cunninghamia Chinese fir canopy reflectance NIR EVI2 geometric optical radiative transfer (GORT) model |
| url | http://www.mdpi.com/2072-4292/10/2/262 |
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