The Park District represents most of South Buffalo, up to William Street on the east and the Buffalo River on the west, with a patchwork of streets making up its northern border. Incumbent Louis J. Petrucci announced this winter he would not seek another term. Adrian F. Harris, a teacher’s aide in a nearby school district, and Carl P. Paladino, a prominent local developer, are vying May 7 for a three-year term to represent the district on the Buffalo Board of Education.