Characterising the Aboveground Carbon Content of Saltmarsh in Jervis Bay, NSW, Using ArborCam and PlanetScope

Coastal ecosystems, including saltmarsh, provide important ecosystem services, including blue carbon storage, nutrient cycling, and coastal protection. The loss or degradation of saltmarsh ecosystems may undermine their capacity to provide these services and drive carbon emission increases. The accu...

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Main Authors: Elizabeth Warwick-Champion, Kevin P. Davies, Paul Barber, Naviin Hardy, Eleanor Bruce
Format: Article
Language:English
Published: MDPI AG 2022-04-01
Series:Remote Sensing
Subjects:
Online Access:https://www.mdpi.com/2072-4292/14/8/1782
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author Elizabeth Warwick-Champion
Kevin P. Davies
Paul Barber
Naviin Hardy
Eleanor Bruce
author_facet Elizabeth Warwick-Champion
Kevin P. Davies
Paul Barber
Naviin Hardy
Eleanor Bruce
author_sort Elizabeth Warwick-Champion
collection DOAJ
description Coastal ecosystems, including saltmarsh, provide important ecosystem services, including blue carbon storage, nutrient cycling, and coastal protection. The loss or degradation of saltmarsh ecosystems may undermine their capacity to provide these services and drive carbon emission increases. The accurate mapping and monitoring of the aboveground carbon content in these ecosystems supports protection and rehabilitation activities. Previous studies have used medium resolution satellites (e.g., Landsat and Sentinel-2) to characterise saltmarsh communities; however, these platforms are not well suited to the fine-scale patchiness of the saltmarsh ecosystems found in Australia. Here we explore the potential of a very high spatial resolution (0.15 m), seven-band multispectral ArborCam airborne sensor and 3 m images captured by the PlanetScope satellite constellation for mapping and monitoring the aboveground carbon content of a saltmarsh ecosystem in Jervis Bay National Park, Australia. The Normalized Difference Vegetation Index (NDVI) derived from an ArborCam image was calibrated to aboveground carbon content using field survey data. Strong linear relationships between the ArborCam NDVI and aboveground carbon content were found when survey data were partitioned by species. The mean aboveground carbon content derived from the calibrated ArborCam image was 1.32 Mg C ha<sup>−1</sup> across the study area; however, this is likely to have been underestimated. A monthly NDVI time series derived from 12 PlanetScope images was analysed to investigate the short-term temporal variation in saltmarsh phenology, and significant intra-annual variation was found. An exploration of potential drivers for the variation found that local rainfall was a potential driver. The combination of the very high spatial resolution airborne ArborCam image and the regular 3 m capture by PlanetScope satellites was found to have potential for accurate mapping and monitoring of aboveground carbon in saltmarsh communities. Future work will focus on improving aboveground carbon estimates by including a very high spatial resolution species distribution map and investigating the influence of temporal variations in saltmarsh spectral response on these estimates.
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spelling doaj.art-6aaa44458463494784821a29b1d5f4422023-11-30T21:50:11ZengMDPI AGRemote Sensing2072-42922022-04-01148178210.3390/rs14081782Characterising the Aboveground Carbon Content of Saltmarsh in Jervis Bay, NSW, Using ArborCam and PlanetScopeElizabeth Warwick-Champion0Kevin P. Davies1Paul Barber2Naviin Hardy3Eleanor Bruce4Faculty of Science, School of Geosciences, University of Sydney, Sydney, NSW 2006, AustraliaFaculty of Science, School of Geosciences, University of Sydney, Sydney, NSW 2006, AustraliaCentre for CubeSats, UAV and Their Applications (CUAVA), University of Sydney, Sydney, NSW 2006, AustraliaArborCarbon, Rota Trans 1, Murdoch, WA 6150, AustraliaFaculty of Science, School of Geosciences, University of Sydney, Sydney, NSW 2006, AustraliaCoastal ecosystems, including saltmarsh, provide important ecosystem services, including blue carbon storage, nutrient cycling, and coastal protection. The loss or degradation of saltmarsh ecosystems may undermine their capacity to provide these services and drive carbon emission increases. The accurate mapping and monitoring of the aboveground carbon content in these ecosystems supports protection and rehabilitation activities. Previous studies have used medium resolution satellites (e.g., Landsat and Sentinel-2) to characterise saltmarsh communities; however, these platforms are not well suited to the fine-scale patchiness of the saltmarsh ecosystems found in Australia. Here we explore the potential of a very high spatial resolution (0.15 m), seven-band multispectral ArborCam airborne sensor and 3 m images captured by the PlanetScope satellite constellation for mapping and monitoring the aboveground carbon content of a saltmarsh ecosystem in Jervis Bay National Park, Australia. The Normalized Difference Vegetation Index (NDVI) derived from an ArborCam image was calibrated to aboveground carbon content using field survey data. Strong linear relationships between the ArborCam NDVI and aboveground carbon content were found when survey data were partitioned by species. The mean aboveground carbon content derived from the calibrated ArborCam image was 1.32 Mg C ha<sup>−1</sup> across the study area; however, this is likely to have been underestimated. A monthly NDVI time series derived from 12 PlanetScope images was analysed to investigate the short-term temporal variation in saltmarsh phenology, and significant intra-annual variation was found. An exploration of potential drivers for the variation found that local rainfall was a potential driver. The combination of the very high spatial resolution airborne ArborCam image and the regular 3 m capture by PlanetScope satellites was found to have potential for accurate mapping and monitoring of aboveground carbon in saltmarsh communities. Future work will focus on improving aboveground carbon estimates by including a very high spatial resolution species distribution map and investigating the influence of temporal variations in saltmarsh spectral response on these estimates.https://www.mdpi.com/2072-4292/14/8/1782aboveground carbon contentsaltmarshArborCamPlanetScopeJervis Bay NSW
spellingShingle Elizabeth Warwick-Champion
Kevin P. Davies
Paul Barber
Naviin Hardy
Eleanor Bruce
Characterising the Aboveground Carbon Content of Saltmarsh in Jervis Bay, NSW, Using ArborCam and PlanetScope
Remote Sensing
aboveground carbon content
saltmarsh
ArborCam
PlanetScope
Jervis Bay NSW
title Characterising the Aboveground Carbon Content of Saltmarsh in Jervis Bay, NSW, Using ArborCam and PlanetScope
title_full Characterising the Aboveground Carbon Content of Saltmarsh in Jervis Bay, NSW, Using ArborCam and PlanetScope
title_fullStr Characterising the Aboveground Carbon Content of Saltmarsh in Jervis Bay, NSW, Using ArborCam and PlanetScope
title_full_unstemmed Characterising the Aboveground Carbon Content of Saltmarsh in Jervis Bay, NSW, Using ArborCam and PlanetScope
title_short Characterising the Aboveground Carbon Content of Saltmarsh in Jervis Bay, NSW, Using ArborCam and PlanetScope
title_sort characterising the aboveground carbon content of saltmarsh in jervis bay nsw using arborcam and planetscope
topic aboveground carbon content
saltmarsh
ArborCam
PlanetScope
Jervis Bay NSW
url https://www.mdpi.com/2072-4292/14/8/1782
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