Linear Corridor

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

What it shows

This layer maps linear ecological corridors identified within France's Green and Blue Network (Trame Verte et Bleue). These corridors are the connective pathways that allow species to move between habitats. The layer matters because development across or near a corridor can interrupt ecological continuity and fragment the wider habitat network.

How it is built

France's Green and Blue Network is a biodiversity-preservation tool that embeds the maintenance and strengthening of natural-environment functionality into planning and development. It is defined at the regional level through the Regional Schemes of Ecological Coherence (SRCE). The network's ecological continuities comprise biodiversity reservoirs and ecological corridors; this layer captures the linear-corridor component. The corridors are delivered as mapped polygons.

How to read it

This is a boundary layer. A site that intersects, or lies close to, a linear corridor should be flagged, since the corridor's role is to keep habitats connected and any interruption can reduce that connectivity.

Class thresholds

This is a categorical / presence (boundary) layer, not a model of a continuous physical quantity. The dataset is a set of 28,606 linear-corridor polylines from France's Regional Schemes of Ecological Coherence (SRCE). The symbolised field (SRCE Corridor — Class 1 category, MILMAJ_NAT) is a qualitative habitat type — Woodland, Humid, Littoral, Multiframe, Non-classified, Open — not a value binned into risk classes. There is therefore no measured flux and no numeric class breaks; the colours distinguish corridor habitat type, not severity.

The "classes" are simply presence versus proximity: a site either overlaps (or lies near) a mapped corridor, or it does not. This layer is not used in materiality scoring (it is contextual), and the TOML defines no proximity trigger and no buffer distance, so there is no risk-flag threshold; the relevant consideration is overlap with, or closeness to, a mapped corridor.

How these thresholds were set. Not applicable — there is no quantitative classification. The corridor boundaries and their habitat-type categories are defined by the Regional Schemes of Ecological Coherence (SRCE), France (methodology after Allag-Dhuisme et al., 2010); Darwin uses those boundaries directly without any numeric classification.

Reference: SRCE — Trame Verte et Bleue, France (trameverteetbleue.fr).

Source

Regional Schemes of Ecological Coherence (SRCE), France — methodology after Allag-Dhuisme et al. (2010), via trameverteetbleue.fr.

Comparison with the WWF Risk Filter Suite

There is no global equivalent in the WWF Risk Filter Suite. As a French regional connectivity dataset, it loosely supports WWF's ecosystem-condition / connectivity theme (S14_5), but WWF's connectivity input is the global functional-connectivity surface (Brennan, 2022), which Darwin does not yet hold globally. This layer is therefore a national extension rather than a WWF indicator.

Legend

Symbolised field: SRCE Corridor - Class 1 category

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