7The provisions of section 16 of the [1982 c. 42.] Welsh Development Agency Act 1975 and of section 1 of the [1975 c. 70.] Derelict Land Act 1982 (powers for the improvement of land) shall have effect in relation to land in a National Park for which a National Park authority is the local planning authority as if references in those provisions to a local authority included references to the National Park authority and as if the relevant Park were the authority’s area.