One of the surest signs that spring has sprung is Party in the Park, the annual benefit for the Emerald Necklace Conservancy. Held yesterday under an enormous – and somewhat overheated – tent in the Fenway, the event attracted hundreds of people, many of them sporting a stylish chapeau. (We spied Yolanda Cellucci, Tonya Chen Mezrich, Beth Dickerson, Krista Ference, Anne Hawley, Ted Cutler, Norman Leventhal, Jan Brett, Debby Kelly, and Sukey Forbes, among many others.) This year’s Liff Spirit Award, which is presented annually at Party in the Park, went to MFA director Malcolm Rogers. The award, named for Justine Mee Liff, Boston’s Commissioner of Parks and Recreation from 1996 to 2002, honors individuals whose “leadership, commitment to cities, passion for public places, and dedication to the democratic ideals fostered in urban parks’’ reflects Liff’s legacy.