Surface Corridor

Source: SRCE — Trame verte et bleue (France) Year: 2013-2015 Category: Transition risks · Sensitive areas · Critical areas · SRCE (France) Coverage: Region (France) Format: Boundary polygons Used in risk analysis: No (contextual layer; not used in materiality scoring)

What it shows

This layer maps surface ecological corridors identified under France's Green and Blue Network (Trame Verte et Bleue). These are areal connecting habitats that allow species to move between core biodiversity reservoirs. They matter for nature-related risk because development that fragments or degrades a corridor can weaken regional ecological connectivity and is subject to planning scrutiny in France.

How it is built

The Green and Blue Network is a French biodiversity-preservation framework that integrates the maintenance and strengthening of functional natural environments into planning and development projects (Allag-Dhuisme et al., 2010). It is delineated at the regional level through the Regional Ecological Coherence Schemes (SRCE). The ecological continuities it defines comprise biodiversity reservoirs and ecological corridors; this layer represents the surface (areal) corridor component, mapped as boundaries identified by regional authorities.

How to read it

This is a boundary layer. A site that intersects or lies close to a mapped surface corridor is flagged as potentially affecting regional ecological connectivity, warranting closer review. There is no numeric score — relevance is determined by spatial overlap or proximity.

Class thresholds

This is a categorical / boundary layer, not a physical-flux surface, so it has no numeric thresholds. The mapped features are surface (areal) ecological corridors of France's Green and Blue Network (Trame Verte et Bleue), and the "classes" are simply the dominant habitat sub-network of each corridor — Woodland, Humid, Littoral, Multiframe, Non-classified or Open (field MILMAJ_NAT). These categories drive the map colours only; they do not rank risk.

There is no risk-flag threshold: this is a contextual layer and is not used in materiality scoring. Relevance is established purely by spatial overlap with, or proximity to, a mapped corridor polygon — the layer carries no proximity buffer distance in its configuration.

How these thresholds were set. Not applicable. The corridor boundaries and their habitat categories come directly from the Regional Ecological Coherence Schemes (SRCE) delineated by French regional authorities (Allag-Dhuisme et al., 2010); Darwin applies no additional classification.

Source

Regional Ecological Coherence Schemes (SRCE), France — Trame Verte et Bleue (Allag-Dhuisme et al., 2010).

Comparison with the WWF Risk Filter Suite

There is no equivalent indicator in the WWF Risk Filter Suite. The SRCE corridors loosely support the theme of ecological connectivity, but they are a regional French dataset. WWF's connectivity input is the global Brennan (2022) functional-connectivity surface, which Darwin does not yet hold globally, so this layer is a regional extension rather than a WWF-comparable indicator.

Legend

Symbolised field: SRCE Corridor - Class 1 category

Generated from darwin/layers/layer-surface-corridor.toml and risk_indicator_pairs.toml (develop).