Methodology

Data products

• Copernicus Sentinel-2 (10 m). Multispectral surface reflectance. The basis for green ground cover inside and around the site.
• Sentinel-2 scene classification layer. Flags cloud, cloud shadow and snow per pixel. Flagged pixels are removed before any figure is computed.
• EFFIS fire history. Mapped burnt-area perimeters from the European Forest Fire Information System. Gives distance, year and size of past fires near the site.
• Spanish PNOA orthophotograph (0.25 m). High-resolution aerial imagery for Spanish sites. Used for visual context of access routes, perimeter and cleared strips, not for computed figures.
• OpenStreetMap. Site outline where one is mapped. Defines the perimeter from which buffer bands are drawn.

Boundary buffer bands

Bands are drawn outward from the site perimeter as concentric rings at fixed distances. Each band is evaluated separately, so vegetation directly at the fence line is not averaged away by open land further out. Band distances are stated in each report.

Green ground cover

Each 10 m pixel is classified as green vegetation or not from its red and near-infrared reflectance. The figure reported is the share of ground area within a band classified as green. It is given as a percentage of ground area rather than as an index value because a percentage can be read without knowing the index scale, and because it can be compared directly between bands, quarters and sites.

Spring and summer as a pair

Vegetation that has dried out in summer reflects like bare ground. On a summer image alone, cured grass reads as cleared land, although it is still present as fuel. Reporting spring and summer together shows how much of the summer's apparently bare ground was green growth a few months earlier.

Tolerance and non-findings

Every figure carries a tolerance that reflects pixel size, residual cloud masking and acquisition differences. A change smaller than its tolerance cannot be distinguished from measurement noise and is therefore reported as a non-finding, not as an improvement or a deterioration.

Limitations

• Green cover is not fuel weight.
• Clearance width against a specification cannot be verified from imagery.
• The orthophotograph may predate the report.
• Fires below roughly 30 hectares are not in the source record.
• Site geometry is not cadastral.