Nature content layer — Task

Implementation: Nature content layer (Recipe - QGIS).

Nature content layer is the Task of bringing the different kinds of semi-natural habitat in an agricultural landscape into one polygon layer: protected nature (§3), larger woodlands, hedges and streams. Together they are the landscape’s nature content, the patches that species live in and move between. Every later habitat analysis starts from this layer, so what goes into it decides what the network can show.

Used in examples: Habitat network at Ledreborg (Example).

Task Schema (tool-agnostic)

1. Decide what counts as nature content (decision point) — which habitat types, and with which thresholds (minimum woodland size, which hedge types).
2. Get each source for the study area plus a margin (Operator: clip to extent) — a margin of about 1 km, so patches just outside the area still count.
3. Select what qualifies (Operator: selection by attribute) — e.g. woodland ≥ 5 ha, living hedges only, open (not piped) streams.
4. Give lines a width (Operator: dilation) — hedges and streams are lines in the data but strips of habitat in reality.
5. Label each source (decision point) — a field saying which kind of nature each patch is.
6. Put the sources together (Operator: merge) — one layer, features unchanged, overlaps kept.

Output: one polygon layer of nature patches with a type field, covering the study area and its margin.

Epistemic Choices to record

• Thresholds: “larger woodland” as ≥ 5 ha (or 0.5 ha, or all woodland) changes the number of patches a lot; say why the chosen threshold fits the question.
• Data quality of each source: in GeoDanmark most hedges have no recorded type (Ikke tildelt); keeping only the ones marked as living hedges leaves real hedges out, keeping all of them adds garden hedges and fences. Say which and why.
• Widths given to lines: a 5 m hedge, a stream with its 2 m cultivation-free bank zone. The widths affect areas, not connectivity at distances of 50 m or more.
• Overlaps: a §3 bog inside a woodland is counted twice if areas are summed per type; dissolve before measuring total nature area.
• Date: each source has its own date; the layer is as old as its oldest source.