Evaluating the Applications of the Near-Infrared Region in Mapping Foliar N in the Miombo Woodlands
Abstract
:1. Introduction
2. Materials and Methods
2.1. Study Area
2.2. Field Nitrogen Data
2.3. Remote Sensing Data
2.4. Spectral Indices
2.5. Random Forest Regression
2.6. Model Evaluation
3. Results
3.1. Individual Bands
3.2. Spectral Indices
3.3. Predictions of Foliar N
4. Discussion
5. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Band | Central Wavelength (µm) | Spatial Resolution (m) |
---|---|---|
B2- Blue | 0.490 | 10 |
B3- Green | 0.560 | 10 |
B4- Red | 0.665 | 10 |
B5- Red edge | 0.705 | 20 |
B6- Red edge | 0.740 | 20 |
B7- Red edge | 0.783 | 20 |
B8- NIR | 0.842 | 10 |
B8a- NIR | 0.865 | 20 |
B11- SWIR | 1.610 | 20 |
B12- SWIR | 2.190 | 20 |
Index | Formula | Sentinel-2 Bands Used | Reference |
---|---|---|---|
Modified Transformed Chlorophyll Absorption in Reflectance Index (TCARI) | B3, B5, B6 | [45] | |
Simple ratio Index (RVI) | B8, B4 | [46] | |
Normalised Difference Vegetation Index (NDVI) | B4, B8 | [47] | |
# Red Edge Chlorophyll Index (CIre) | B5, B8 | [48] | |
# Green Chlorophyll Index (CIg) | B3, B7 | [48] | |
Green Index (GI) | B4, B5, B6, B8 | [46] | |
# Normalised difference Red edge index (NDVIre) | B5, B6 | [49] | |
Enhanced Vegetation Index 2 (EVI2) | B4, B8 | [50] |
Predictor Variables | nRMSE (%) | Bias (%) | r2 |
---|---|---|---|
All bands | 11.35 | 0.06 | 0.94 |
All bands excluding the NIR | 11.69 | 0.07 | 0.93 |
All spectral indices | 12.90 | 0.07 | 0.90 |
All spectral indices excluding the NIR-based | 13.45 | 0.08 | 0.89 |
All bands and spectral indices | 11.09 | 0.06 | 0.94 |
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Mutowo, G.; Mutanga, O.; Masocha, M. Evaluating the Applications of the Near-Infrared Region in Mapping Foliar N in the Miombo Woodlands. Remote Sens. 2018, 10, 505. https://doi.org/10.3390/rs10040505
Mutowo G, Mutanga O, Masocha M. Evaluating the Applications of the Near-Infrared Region in Mapping Foliar N in the Miombo Woodlands. Remote Sensing. 2018; 10(4):505. https://doi.org/10.3390/rs10040505
Chicago/Turabian StyleMutowo, Godfrey, Onisimo Mutanga, and Mhosisi Masocha. 2018. "Evaluating the Applications of the Near-Infrared Region in Mapping Foliar N in the Miombo Woodlands" Remote Sensing 10, no. 4: 505. https://doi.org/10.3390/rs10040505