ATTLEBORO — An environmental group is hoping the city will help its efforts to save the right whales — by planting a forest or two.

The Ocean River Institute recently visited Attleboro because, when contacting eight cities to discuss planting what are called Miyawaki forests, Attleboro was the most responsive.

They found two potential sites for these dense urban forests in which they’d plant about 40 different species of woody plants and trees: O’Connell Field next to Capron Park Zoo and Highland Park.

Neither Zoo Director John Wright nor Mayor Cathleen DeSimone returned calls or emails seeking comment.

Japanese botanist Akira Miyawaki developed a way to increase plant photosynthesis, carbon draw down and soil development. His forests, with dozens of species clumped in a very small area, increases the water in the ground by 10.

“They create a super sponge,” said Rob Moir, president and executive director of Ocean River Institute.

With its population falling, the right whale is Massachusetts’ most endangered whale. To restore the right whale population to where it was 25 years ago, people must modify their actions on the land, he said.

Pollutants have increased and the temperature of the ocean is rising, Moir said, and both are harmful to right whales, a vital part of the ocean’s ecosystem.

Planting a Miyawaki forest in several cities would have a strong impact on the environment by increasing carbon monoxide intake and reducing the amount of water with pollutants to the ocean, he said.

“This will slow (the deterioration of the whales’ habitat) down,” Moir said. “But it’s going to take time.”

The Miyawaki forest proposed between the zoo and Attleboro High School would be helpful for education and research, he said. A trail would circle the forest.

Plantings spaced 18 inches apart will be too close together to permit walking in the forest for the first five years or so. Signage would explain the forest’s benefits for both people and wildlife.

Highland Park is another potential site for a Miyawaki forest. The forest would be planted in the southeast corner, where residents on Dennis Street have suffered from stormwater runoff.

It will act as a giant sponge, absorbing water and letting it infiltrate into the ground, he said, benefiting everyone during the dry season.

The cost of planting a Miyawaki forest is about $20,000, not including the land or maintenance.

Moir said if Attleboro chose to have a Miyawaki forest, a number of groups may be interested in assisting with fundraising. Government grants are also available, he said.

There are now two Miyawaki forests in Cambridge and one in Somerville.

The Cambridge-based nonprofit group is also calling for the federal government to create the Right Whale National Marine Sanctuary in approximately 6,500 square miles of ocean around Cape Cod, from Block Island to Stellwagen Bank north of Provincetown.