"advocate of protecting existing things," 1905, from preservation + -ist; specifically of historic buildings by 1957.
Entries linking to preservationist
preservation n.
early 15c., preservacioun "protection from disease," from Old French preservacion (13c.), from Medieval Latin preservationem (nominative preservatio), noun of action from past-participle stem of preservare "to guard beforehand" (see preserve (v.)). General sense of "protection, act of keeping safe or sound" is from mid-15c.
-ist
word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes.
Variant -ister (as in chorister, barrister) is from Old French -istre, on false analogy of ministre. Variant -ista is from Spanish, popularized in American English 1970s by names of Latin-American revolutionary movements.