A funeral service for Stuart Gersen, the co-owner of one of Portland’s most beloved bookstores, was held Tuesday morning at Portland’s Evergreen Cemetery.

Gersen, who was 64, died Saturday at Gosnell Memorial Hospice House in Scarborough. He died of lung cancer, according to his obituary.

Gersen and his business partner, Chris Bowe, have owned and operated Longfellow Books in Monument Square since 2001. They opened in that space after Bookland closed as the result of the business filing for bankruptcy. Gersen and Bowe were former Bookland employees at the time.

The bookstore, which is normally open until 7 p.m. on weekdays, was closed Tuesday afternoon and evening. A sign in the store window read, “Closed in memory of Stuart Gersen, 1950-2015.”

Gersen developed a reputation for being a strong supporter of keeping Portland independent and was one of the founding members of Portland’s Buy Local organization. Longfellow Books is only one of two bookstores on the city’s peninsula that sells new books.

“He was a great person, business owner, community member and one of the founders of Portland Buy Local. Our hearts are heavy but our will is strong to carry on his mission to keep Portland Independent,” a message posted on Portland Buy Local’s Facebook page read.

In his obituary, his family said that Gersen has been advocating for authors and readers for most of his adult life and was honored to be a part of the community that he helped create over the years at Longfellow Books. Longfellow Books promoted Maine authors and writers by hosting free book signings and readings after hours.

Yarmouth writer Lily King, who has been nominated for a major national book award, attended Gersen’s funeral Tuesday. King met Gersen in 1999 at a bookseller’s convention.

“He was so big hearted and full of enthusiasm, and such a true lover of books. I just loved him the minute I met him,” King said. “He has been so supportive of my work for so many years, and so supportive of so many writers. I don’t think there is a writer in Maine who wouldn’t say the same thing.”

“This is like the falling of a redwood,” Thomas Ryan, an acquaintance, who lives in Paris, France, wrote on the Portland Press Herald’s online obituary guest book. “Stuart’s voice and wit and the wonderful books he shared with Portland will long be remembered. Happy trails, mon ami.”

In lieu of flowers, donations may be sent to the New England Cancer Center and the Portland Public Library.