Instead of a gerund with an object, Latin usually puts the noun in the needed case and makes the gerundive agree with it: ad animum serenandum "for calming the mind".
Pattern: preposition or case + noun + gerundive agreeing with it. Translate the gerundive as an English "-ing" with the noun as its object: ad eandem conservandam "for preserving it", literally "for it to-be-preserved".
There is no form of sum here; a gerundive with sum expresses obligation (see the gerundive of obligation).