Nature content layer — Recipe (QGIS)

Tool-bound implementation of the Nature content layer (Task) Task Schema in QGIS 4.2. Worked example: Habitat network at Ledreborg (Example).

Data you need

Role	Form	Level of measurement	Notes
Protected habitats	polygons	nominal habitat type	e.g. the national register of protected nature types
Woodland	polygons	—	area is computed from the geometry
Linear habitats (hedges, streams)	lines	nominal type, if the source has one	e.g. a type field that separates living hedges from fences, or open from piped streams
Nature content (output)	polygons	nominal (nature field)	one layer, all sources

All sources for the study area plus a margin (about 1 km), in the same CRS.

Get the sources (Task Schema step 2)

Load each source for the map extent (e.g. with the SemanticGIS plugin) and save a local copy: Export › Save Features As… with Extent = map canvas, or all at once with Package layers (Tool - QGIS).

Select what qualifies (step 3)

Extract by expression (Tool - QGIS) on each source, with the conditions the Task’s choices call for, e.g.

• a minimum size: $area >= <m²>
• a type: "<type field>" = '<value>'

Give lines a width (step 4)

Buffer (Tool - QGIS) on each line layer with half the habitat strip’s width as Distance; Dissolve result off.

Label and merge (steps 5–6)

1. On each layer, Field calculator (Tool - QGIS): a text field nature, either a fixed label ('Woodland') or a source field ("<type field>").
2. Retain fields (Vector table) keeps only nature on each layer, so the merge does not stumble over different fields.
3. Merge vector layers (Tool - QGIS) with all layers and the project’s CRS as Destination CRS.

Checked in QGIS 4.2.2, October 2026.