UAV-Hyperspectral Imaging to Estimate Species Distribution in Salt Marshes: A Case Study in the Cadiz Bay (SW Spain)
Salt marshes are one of the most productive ecosystems and provide numerous ecosystem services. However, they are seriously threatened by human activities and sea level rise. One of the main characteristics of this environment is the distribution of specialized plant species. The environmental condi...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-03-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/15/5/1419 |
| _version_ | 1797614470798770176 |
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| author | Andrea Celeste Curcio Luis Barbero Gloria Peralta |
| author_facet | Andrea Celeste Curcio Luis Barbero Gloria Peralta |
| author_sort | Andrea Celeste Curcio |
| collection | DOAJ |
| description | Salt marshes are one of the most productive ecosystems and provide numerous ecosystem services. However, they are seriously threatened by human activities and sea level rise. One of the main characteristics of this environment is the distribution of specialized plant species. The environmental conditions governing the distribution of this vegetation, as well as its variation over time and space, still need to be better understood. In this way, these ecosystems will be managed and protected more effectively. Low-altitude remote sensing techniques are excellent for rapidly assessing salt marsh vegetation coverage. By applying a high-resolution hyperspectral imaging system onboard a UAV (UAV-HS), this study aims to differentiate between plant species and determine their distribution in salt marshes, using the salt marshes of Cadiz Bay as a case study. Hyperspectral processing techniques were used to find the purest spectral signature of each species. Continuum removal and second derivative transformations of the original spectral signatures highlight species-specific spectral absorption features. Using these methods, it is possible to differentiate salt marsh plant species with adequate precision. The elevation range occupied by these species was also estimated. Two species of <i>Sarcocornia</i> spp. were identified on the Cadiz Bay salt marsh, along with a class for <i>Sporobolus maritimus</i>. An additional class represents the transition areas from low to medium marsh with different proportions of <i>Sarcocornia</i> spp. and <i>S. maritimus</i>. <i>S. maritimus</i> can be successfully distinguished from soil containing microphytobenthos. The final species distribution map has up to 96% accuracy, with 43.5% of the area occupied by medium marsh species (i.e., <i>Sarcocornia</i> spp.) in the 2.30–2.80 m elevation range, a 29% transitional zone covering in 1.91–2.78 m, and 25% covered by <i>S. maritims</i> (1.22–2.35 m). Basing a method to assess the vulnerability of the marsh to SLR scenarios on the relationship between elevation and species distribution would allow prioritizing areas for rehabilitation. UAV-HS techniques have the advantage of being easily customizable and easy to execute (e.g., following extreme events or taking regular measurements). The UAV-HS data is expected to improve our understanding of coastal ecosystem responses, as well as increase our capacity to detect small changes in plant species distribution through monitoring. |
| first_indexed | 2024-03-11T07:11:52Z |
| format | Article |
| id | doaj.art-c38890e039b2483d8dbec7505884f2aa |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-11T07:11:52Z |
| publishDate | 2023-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-c38890e039b2483d8dbec7505884f2aa2023-11-17T08:32:51ZengMDPI AGRemote Sensing2072-42922023-03-01155141910.3390/rs15051419UAV-Hyperspectral Imaging to Estimate Species Distribution in Salt Marshes: A Case Study in the Cadiz Bay (SW Spain)Andrea Celeste Curcio0Luis Barbero1Gloria Peralta2Department of Earth Sciences, Faculty of Marine and Environmental Sciences, International Campus of Excellence in Marine Science (CEIMAR), University of Cadiz, 11510 Puerto Real, SpainDepartment of Earth Sciences, Faculty of Marine and Environmental Sciences, International Campus of Excellence in Marine Science (CEIMAR), University of Cadiz, 11510 Puerto Real, SpainDepartment of Biology, Faculty of Marine and Environmental Sciences, International Campus of Excellence in Marine Science (CEIMAR), University of Cadiz, 11510 Puerto Real, SpainSalt marshes are one of the most productive ecosystems and provide numerous ecosystem services. However, they are seriously threatened by human activities and sea level rise. One of the main characteristics of this environment is the distribution of specialized plant species. The environmental conditions governing the distribution of this vegetation, as well as its variation over time and space, still need to be better understood. In this way, these ecosystems will be managed and protected more effectively. Low-altitude remote sensing techniques are excellent for rapidly assessing salt marsh vegetation coverage. By applying a high-resolution hyperspectral imaging system onboard a UAV (UAV-HS), this study aims to differentiate between plant species and determine their distribution in salt marshes, using the salt marshes of Cadiz Bay as a case study. Hyperspectral processing techniques were used to find the purest spectral signature of each species. Continuum removal and second derivative transformations of the original spectral signatures highlight species-specific spectral absorption features. Using these methods, it is possible to differentiate salt marsh plant species with adequate precision. The elevation range occupied by these species was also estimated. Two species of <i>Sarcocornia</i> spp. were identified on the Cadiz Bay salt marsh, along with a class for <i>Sporobolus maritimus</i>. An additional class represents the transition areas from low to medium marsh with different proportions of <i>Sarcocornia</i> spp. and <i>S. maritimus</i>. <i>S. maritimus</i> can be successfully distinguished from soil containing microphytobenthos. The final species distribution map has up to 96% accuracy, with 43.5% of the area occupied by medium marsh species (i.e., <i>Sarcocornia</i> spp.) in the 2.30–2.80 m elevation range, a 29% transitional zone covering in 1.91–2.78 m, and 25% covered by <i>S. maritims</i> (1.22–2.35 m). Basing a method to assess the vulnerability of the marsh to SLR scenarios on the relationship between elevation and species distribution would allow prioritizing areas for rehabilitation. UAV-HS techniques have the advantage of being easily customizable and easy to execute (e.g., following extreme events or taking regular measurements). The UAV-HS data is expected to improve our understanding of coastal ecosystem responses, as well as increase our capacity to detect small changes in plant species distribution through monitoring.https://www.mdpi.com/2072-4292/15/5/1419coastal marshcontinuum removalhyperspectralspectral signaturesunmanned aerial vehicle (UAV)vegetation species discrimination |
| spellingShingle | Andrea Celeste Curcio Luis Barbero Gloria Peralta UAV-Hyperspectral Imaging to Estimate Species Distribution in Salt Marshes: A Case Study in the Cadiz Bay (SW Spain) Remote Sensing coastal marsh continuum removal hyperspectral spectral signatures unmanned aerial vehicle (UAV) vegetation species discrimination |
| title | UAV-Hyperspectral Imaging to Estimate Species Distribution in Salt Marshes: A Case Study in the Cadiz Bay (SW Spain) |
| title_full | UAV-Hyperspectral Imaging to Estimate Species Distribution in Salt Marshes: A Case Study in the Cadiz Bay (SW Spain) |
| title_fullStr | UAV-Hyperspectral Imaging to Estimate Species Distribution in Salt Marshes: A Case Study in the Cadiz Bay (SW Spain) |
| title_full_unstemmed | UAV-Hyperspectral Imaging to Estimate Species Distribution in Salt Marshes: A Case Study in the Cadiz Bay (SW Spain) |
| title_short | UAV-Hyperspectral Imaging to Estimate Species Distribution in Salt Marshes: A Case Study in the Cadiz Bay (SW Spain) |
| title_sort | uav hyperspectral imaging to estimate species distribution in salt marshes a case study in the cadiz bay sw spain |
| topic | coastal marsh continuum removal hyperspectral spectral signatures unmanned aerial vehicle (UAV) vegetation species discrimination |
| url | https://www.mdpi.com/2072-4292/15/5/1419 |
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