Why does aspect matter for restoration?
Slopes that face the sun through the dry season dry out sooner, and seedlings there can survive less often. Which direction that is depends on latitude and season, so the analysis reports all eight.
Terrain aspect and slope
Which way do the slopes face, and how steep are they? Slope orientation changes how much sun and drying a site gets, which matters for seedling survival in dry forest. The analysis measures the area facing each of eight compass directions, the flat ground, and four slope classes, from a bare-earth terrain model by default.
Who it is for
Carbon project developers
Plan planting and survival assumptions by slope, and keep steep ground in view for access and erosion.
Restoration and planting teams
Match species and planting to aspect and slope, and place plots across the range of conditions.
Funders
Understand why survival can differ from one part of a site to another.
What goes in
A property boundary as a polygon, and these settings, which you can change before each run.
| Setting | Default | Range |
|---|---|---|
| Elevation model. Auto uses bare-earth GEDTM30 and falls back to Copernicus GLO-30. | Auto (GEDTM30 bare-earth) | Auto (GEDTM30 bare-earth) · GEDTM30 bare-earth · Copernicus GLO-30 (includes canopy) |
| Slopes gentler than this count as flat instead of facing a direction. | 3 | 0–15 |
Data sources
- GEDTM30 v1.2 (OpenGeoHub)Bare-earth terrain estimate, 30 m, from Copernicus GLO-30 (2011–2015) and ALOS AW3D30 (2006–2010) elevation, corrected to the ground with ICESat-2 and GEDI lidar. The default.
- Copernicus DEM GLO-30Surface model, 30 m, that includes the height of trees and buildings. Used only when you pick it or GEDTM30 cannot be read.
What you get
- Hectares and share facing north, northeast, east, southeast, south, southwest, west and northwest, plus flat ground (under 3° by default).
- The dominant direction.
- Slope in four classes, 0–5°, 5–15°, 15–30° and 30° or more, with the mean, median and steepest slope.
- Which terrain model the run used.
Limits
- 30 m cells smooth out small terraces, gullies and stream banks.
- On very gentle ground, noise in the elevation data decides the direction, which is why ground under the flat threshold counts as flat.
- The fallback model includes canopy, so slopes under forest can read wrong; each run records which model it used.
- Up to about 13,500 ha of bounding box per run.
Where it fits in your work
Run it at site planning, once a property is chosen. Aspect and slope feed species choice, planting density, survival expectations and where plots go.
Questions teams ask
Why a bare-earth terrain model?
Surface models measure the top of trees and buildings, so slopes under forest follow the canopy. A bare-earth model estimates the ground beneath, which is what water and roots follow.
Can I change what counts as flat?
Yes. The default is 3°; you can set anything from 0° to 15° before a run.
What do I need to run it?
A property boundary as a polygon, drawn on the map or imported from a KML, shapefile or GeoJSON file. The result is saved on the property, beside its other records and maps.
Run it on your land
Tell us about the properties you are looking at, and we will set the analyses up in your project.