Using Drones to Monitor Broad-Leaved Orchids (<i>Dactylorhiza majalis)</i> in High-Nature-Value Grassland
<i>Dactylorhiza majalis</i> is a threatened indicator species for the habitat quality of nutrient-poor grassland sites. Environmentalists utilize the species to validate the success of conservation efforts. Conventionally, plant surveys are field campaigns where the plant numbers are est...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-07-01
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| Series: | Drones |
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| Online Access: | https://www.mdpi.com/2504-446X/6/7/174 |
| _version_ | 1797406744557649920 |
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| author | Kim-Cedric Gröschler Natascha Oppelt |
| author_facet | Kim-Cedric Gröschler Natascha Oppelt |
| author_sort | Kim-Cedric Gröschler |
| collection | DOAJ |
| description | <i>Dactylorhiza majalis</i> is a threatened indicator species for the habitat quality of nutrient-poor grassland sites. Environmentalists utilize the species to validate the success of conservation efforts. Conventionally, plant surveys are field campaigns where the plant numbers are estimated and their spatial distribution is either approximated by GPS or labor-intensively measured by differential GPS. In this study, we propose a monitoring approach using multispectral drone-based data with a very high spatial resolution (~3 cm). We developed the magenta vegetation index to enhance the spectral response of <i>Dactylorhiza majalis</i> in the drone data. We integrated the magenta vegetation index in a random forest classification routine among other vegetation indices and analyzed feature impact on model decision making using SHAP. We applied an image object-level median filter to the classification result to account for image artefacts. Finally, we aggregated the filtered result to individuals per square meter using an overlaying vector grid. The SHAP analysis showed that magenta vegetation index had the highest impact on model decision making. The random forest model could reliably classify <i>Dactylorhiza majalis</i> in the drone data (F1 score: 0.99). We validated the drone-derived plant count using field mappings and achieved good results with an RMSE of 12 individuals per square meter, which is within the error margin stated by experts for a conventional plant survey. In addition to abundance, we revealed the comprehensive spatial distribution of the plants. The results indicate that drone surveys are a suitable alternative to conventional monitoring because they can aid in evaluating conservation efforts and optimizing site-specific management. |
| first_indexed | 2024-03-09T03:31:01Z |
| format | Article |
| id | doaj.art-ef4428799c6940ebadeb63825aec828e |
| institution | Directory Open Access Journal |
| issn | 2504-446X |
| language | English |
| last_indexed | 2024-03-09T03:31:01Z |
| publishDate | 2022-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Drones |
| spelling | doaj.art-ef4428799c6940ebadeb63825aec828e2023-12-03T14:55:57ZengMDPI AGDrones2504-446X2022-07-016717410.3390/drones6070174Using Drones to Monitor Broad-Leaved Orchids (<i>Dactylorhiza majalis)</i> in High-Nature-Value GrasslandKim-Cedric Gröschler0Natascha Oppelt1Earth Observation and Modelling, Department of Geography, Kiel University, Ludewig-Meyn-Str. 8, 24098 Kiel, GermanyEarth Observation and Modelling, Department of Geography, Kiel University, Ludewig-Meyn-Str. 8, 24098 Kiel, Germany<i>Dactylorhiza majalis</i> is a threatened indicator species for the habitat quality of nutrient-poor grassland sites. Environmentalists utilize the species to validate the success of conservation efforts. Conventionally, plant surveys are field campaigns where the plant numbers are estimated and their spatial distribution is either approximated by GPS or labor-intensively measured by differential GPS. In this study, we propose a monitoring approach using multispectral drone-based data with a very high spatial resolution (~3 cm). We developed the magenta vegetation index to enhance the spectral response of <i>Dactylorhiza majalis</i> in the drone data. We integrated the magenta vegetation index in a random forest classification routine among other vegetation indices and analyzed feature impact on model decision making using SHAP. We applied an image object-level median filter to the classification result to account for image artefacts. Finally, we aggregated the filtered result to individuals per square meter using an overlaying vector grid. The SHAP analysis showed that magenta vegetation index had the highest impact on model decision making. The random forest model could reliably classify <i>Dactylorhiza majalis</i> in the drone data (F1 score: 0.99). We validated the drone-derived plant count using field mappings and achieved good results with an RMSE of 12 individuals per square meter, which is within the error margin stated by experts for a conventional plant survey. In addition to abundance, we revealed the comprehensive spatial distribution of the plants. The results indicate that drone surveys are a suitable alternative to conventional monitoring because they can aid in evaluating conservation efforts and optimizing site-specific management.https://www.mdpi.com/2504-446X/6/7/174biodiversity conservationindicator speciesremote sensingwestern marsh orchidrandom forestvegetation index |
| spellingShingle | Kim-Cedric Gröschler Natascha Oppelt Using Drones to Monitor Broad-Leaved Orchids (<i>Dactylorhiza majalis)</i> in High-Nature-Value Grassland Drones biodiversity conservation indicator species remote sensing western marsh orchid random forest vegetation index |
| title | Using Drones to Monitor Broad-Leaved Orchids (<i>Dactylorhiza majalis)</i> in High-Nature-Value Grassland |
| title_full | Using Drones to Monitor Broad-Leaved Orchids (<i>Dactylorhiza majalis)</i> in High-Nature-Value Grassland |
| title_fullStr | Using Drones to Monitor Broad-Leaved Orchids (<i>Dactylorhiza majalis)</i> in High-Nature-Value Grassland |
| title_full_unstemmed | Using Drones to Monitor Broad-Leaved Orchids (<i>Dactylorhiza majalis)</i> in High-Nature-Value Grassland |
| title_short | Using Drones to Monitor Broad-Leaved Orchids (<i>Dactylorhiza majalis)</i> in High-Nature-Value Grassland |
| title_sort | using drones to monitor broad leaved orchids i dactylorhiza majalis i in high nature value grassland |
| topic | biodiversity conservation indicator species remote sensing western marsh orchid random forest vegetation index |
| url | https://www.mdpi.com/2504-446X/6/7/174 |
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