How does Celestial Dawn affect non-basic lands' abilities? [duplicate]

Question

The part that affects lands on Celestial Dawn says

Lands you control are Plains

In my head, this takes away any other type and abilities those lands have, but the only thing I can find in the rulings for Celestial Dawn is the 29-Sep-2017 ruling that says if the land has an ability that would cause it to enter tapped it doesn't.

So, do my non-basics still get their other abilities, such as Lotus Field tapping for three mana or Serra's Sanctum, adding one white mana for each enchantment I control?

Answer 1

Your initial thought is correct. Quoting Comprehensive Rule 305.7:

If an effect sets a land’s subtype to one or more of the basic land types, the land no longer has its old land type. It loses all abilities generated from its rules text, its old land types, and any copiable effects affecting that land, and it gains the appropriate mana ability for each new basic land type.

The thing to remember here is that the rulings in Gatherer are just explanations of how the Comprehensive Rules apply to a particular situation; they do not aim to cover every possible interaction that a card may have.

Answer 2

No, they don't get other abilities than tapping for one white mana. A similar card is Blood Moon, which states "Nonbasic lands are Mountains.", and its rulings say

Nonbasic lands will lose any other land types and abilities they had. They will gain the land type Mountain and gain the ability “Tap: Add Red.”