Table 3 Selected spectral indices, based on Sentinel-2 bands (Table 2), used to assess alterations in soil properties in three study areas in pine stands affected by crown fire in Spain, in 2018 and 2019: Study areas, with the pre- and post-fire image dates used for each in parentheses, were: Nerva (31 Jul 2018 and 4 Oct 2018), Gavilanes (1 Jun 2019 and 31 Jul 2019), and La Granja (2 Aug 2019 and 6 Sep 2019)
Spectral index | Formulaa | Reference |
|---|---|---|
NBR Normalized Burn Ratio | \( NBR=\frac{\left(B8-B12\right)}{\left(B8+B12\right)} \) | Key and Benson (2006) |
dNBR differenced Normalized Burn Ratio | dNBR = NBRPRE-FIRE − NBRPOST-FIRE | Key and Benson (2006) |
RdNBR Relative difference Normalized Burn Ratio | \( RdNBR=\frac{dNBR}{\sqrt{\frac{\left|{NBR}_{\mathrm{PRE}-\mathrm{FIRE}}\right|}{1000}}} \) | Miller and Thode (2007) |
RBR Relativized Burn Ratio | \( RBR=\frac{dNBR}{\left({NBR}_{\mathrm{PRE}-\mathrm{FIRE}}+1.001\right)} \) | Parks et al. (2014) |
NDVI Normalized Difference Vegetation Index | \( NDVI=\frac{\left(B8-B4\right)}{\left(B8+B4\right)} \) | Rouse (1974) |
dNDVI differenced Normalized Difference Vegetation Index | dNDVI = NDVIPRE-FIRE − NDVIPOST-FIRE | Escuin et al. (2008) |
BAIS2 Burned Area Index for Sentinel-2 | \( BAIS2=\left(1-\sqrt{\frac{B6\times B7\times B8A}{B4}}\right)\times \left(\frac{B12-B8A}{\sqrt{B12-B8A}}+1\right) \) | Filipponi (2018) |
dBAIS2 difference Burned Area Index for Sentinel-2 | dBAIS2 = BAIS2PRE-FIRE − BAIS2POST-FIRE | Filipponi (2018) |
MIRBI Mid-Infrared Burn Index | MIRBI = 10 × B11 − 9.8 × B12 | Trigg and Flasse (2001) |
dMIRBI difference Mid-Infrared Burn Index | dMIRBI = MIRBIPRE-FIRE − MIRBIPOST-FIRE | Tran et al. (2018) |