The subdivider, as a condition of approval of a tentative map, shall dedicate, or make an irrevocable offer of dedication of, all parcels of land within the subdivision that are needed for streets and alleys, including access rights and abutter's rights, drainage, public open space, trails, scenic easements, public utility easements and other public easements, pursuant to Map Act Section 66475. In addition, the subdivider shall improve or agree to improve all the aforementioned dedications and easements.