Nature designation is the constraint that most often stops a scheme outright, and it is the one most often held as a dot on a map when it is really an area. The protected sites map draws all sixteen designations as their real boundaries.

The statutory set

18,413 Sites of Special Scientific Interest, 4,606 Special Areas of Conservation, 3,580 Special Protection Areas and 3,574 Ramsar wetlands, alongside 1,049 National Nature Reserves and 1,951 Local Nature Reserves.

They overlap heavily and deliberately: the same estuary can be SSSI, SAC, SPA and Ramsar at once, each designation protecting a different thing under a different instrument. Counting them as separate places would overstate how much land is designated; treating them as interchangeable would understate what applies.

Marine

144 Marine Conservation Zones, five Highly Protected Marine Areas and 34 Marine Consultation Areas. The marine designations are newer, sparser and less familiar than their terrestrial equivalents, and they matter for exactly the things now being built offshore.

Nutrient neutrality

39 nutrient neutrality catchments — the newest layer here and the one with the most immediate effect on housing. In these catchments, development must demonstrate it adds no net nutrient load before it can proceed, which has held up tens of thousands of homes.

It is a catchment rather than a site: the constraint applies across the land draining to a protected water body, so it reaches a long way from the thing being protected.

Sources

Natural England, NatureScot and Natural Resources Wales designated site registers, under the Open Government Licence v3.