When “Tadashi Kawamata: Tree Huts” opens on Oct. 2, visitors to Madison Square Park will see a collection of small wooden structures tucked into the trees. To some, they may evoke childhood memories of hiding out in treehouses; to others, they may suggest flimsy shelters built by the homeless. Mr. Kawamata, the 55-year-old artist who created the “Kawamata Project on Roosevelt Island,” a web of scaffolding built around the island’s Smallpox Hospital, in 1992, said he is hoping for a variety of reactions. He and five assistants will begin building the huts in the park’s southwest corner, near 23rd Street and Broadway, next Tuesday, Sept. 23, and will continue through Oct. 1. The installation, sponsored by the Madison Square Park Conservancy, will be up until the end of the year, weather permitting. Information: madisonsquarepark.org.