From: Mapping soil nutrients via different covariates combinations: theory and an example from Morocco
Environmental covariates | Sources | Resolution | Resample resolution |
---|---|---|---|
Bioclimatic parameters | |||
Annual mean temperature (bio_1) Max temperature of the warmest month (bio_5) Min temperature of the coldest month (bio_6) Annual precipitation (bio_12) | WorldClim database version 2 | 10 min (~ 340 km2) | 30 m |
Terrain attributes | |||
Elevation; slope; profile curvature; plan curvature, Multi-resolution Valley Bottom Flatness (MrVBF); Multi-resolution Ridge Top Flatness (MrRTF); Topographic wetness index (TWI); convergence index and aspect | ASTER-GDEM | 30 m | 30 m |
Remote sensing indices | |||
Normalized difference vegetation index (NDVI) Transformed normalized difference vegetation index (TNDVI) Soil adjusted vegetation index (SAVI) Ratio vegetation index (RVI) Difference vegetation index (DVI) Chlorophyll vegetation index (CVI) | Landsat OLI 8 | 30 m | 30 m |