Two Mattapoisett elementary school students have won an award for celebrating the town's trees.

The Mattapoisett Tree Committee has been sponsoring a poster contest for the last three years, said member Jodi Bauer. The contest is part of a state requirement to keep Mattapoisett a "Tree City," which it has been for the past 10 years.

Towns designated as Tree Cities by the Arbor Day Foundation work to create a sustainable urban forestry program within town limits.

To maintain Tree City status, the town must complete a certain number of projects within the community, including a youth education portion.

The theme for each poster contest is decided in advance by the Massachusetts Department of Conservation and Recreation, Bauer said.

"This year, they were a bit late with telling us what it was, so we had to scramble a bit."

Ultimately, they decided on "My Community, My Trees." The Tree Committee worked with Old Hammondtown School art teacher Greta Anderson, who gathered 10 students to compete in the poster contest.

When the posters were complete, they were judged by a panel of several Mattapoisett residents and artists, including Bodil Perkins, Dick Morgado, Diane Perry, Mary O'Keefe, Jill Jarvis, Paul Wildnauer, Paula Cobb, John Magnin, Henry Avery, Gary Hoyt, Roxanne Bungert, Barbra Gasper and Colleen Johns.

"It was so wonderful of them to volunteer their time," Bauer said. "I know they had a really tough time deciding on a winner."

First-place winner Caitlin O'Donnell drew a poster of the earth, encircled by a chain of humans, above a tree. "They're all thanking the tree," she explained.

Runner-up Cassandra Tseki drew the different uses and benefits of trees. She said of her poster, "I thought I could draw a picture of everything trees do for us."

For their efforts, O'Donnell won a $25 gift certificate to No Kidding, while Tseki won a $10 certificate to the same store.

The 10 posters designed by the Old Hammondtown students will be displayed at the Mattapoisett Library for the next month.