| Environmental variables (EV) | ||
| Environmental variable | Abbreviation | Proxy for |
| Digital elevation model | DEM | Temperature, topographic variation |
| Slope | Slope | Soil moisture, soil nutrients, soil characteristics |
| Aspect | Aspect | Slope direction, sun exposure |
| Solar radiation | Solar_rad | Insolation |
| Curvature | Curvature | Exposure to wind, water and soil nutrient runoff direction |
| Relative relief 3 × 3 | Rel_3 | Large scale topographic differences, 30 × 30 meters |
| Relative relief 6 × 6 | Rel_6 | Large scale topographic differences, 60 × 60 meters |
| Relative relief 9 × 9 | Rel_9 | Large scale topographic differences, 90 × 90 meters |
| Wetness index | Wet_ind | Groundwater |
| Profile curvature | Prof_curv | Affects the acceleration or deceleration of flow across the surface |
| Planform curvature | Plan_curv | Relates to the convergence and divergence of flow across a surface |