A planning rule requiring a percentage of green space delivers very different biodiversity outcomes depending on whether it also requires that space to connect.
biodiversity_score ~ green_share * connectivity_requirement
- City grid size — development parcels governed by the city masterplan.
- Planned green-space share — minimum green-space allocation mandated per parcel by planning rules.
- Development pressure — how strongly market demand pushes to convert green space to built area.
- Planning connectivity requirement — whether planning rules require new green space to connect to the existing network.
Cities that mandate green-space connectivity in planning code — not just a raw percentage — consistently outperform percentage-only rules on measured biodiversity outcomes.