Gerald Smith and Catherine Badgley won't ever make much money if they decide to sell the field and wetlands they purchased in 1990.

And that's more than OK with them.

The Sylvan Township couple have entered into a contract that guarantees 110 acres of the 120-acre parcel won't ever be divided up for homes or paved over for a strip mall parking lot.

"It’s of high value for us," said Badgley, a University of Michigan biology and ecology professor. "It means more to us than being able to make a lot of money selling it."

This way, Badgley said, an important part of the Huron River watershed will be preserved forever. While far removed from the Huron itself, tributaries connect the property to the river.

The couple purchased the 120-acre parcel outside of Chelsea in 1990. Their timber frame home overlooks the fields and wetlands, and they’ve often invited their students there to learn about the land. Smith is a professor emeritus at the University of Michigan and the former director of the Museum of Zoology.

The couple worked with Legacy Land Conservancy (formerly the Washtenaw Land Trust) to arrange the agreement to preserve the land. The organization exists to preserve nature and farmland in southeast Michigan indefinitely. Legacy Land Conservancy has preserved 3,500 acres to date.

"We can sell the land, but except for a small building envelope, the land cannot be divided for housing or commercial purposes," Badgley said.

Smith and Badgley are naturalists and scientists who have documented more than 80 species of birds and numerous species of mammals, amphibians, reptiles and fish. They’ve also worked hard to knock out invasive species, including autumn olive and thistle, farmed and raised many animals on the land. The agreement allows for some agriculture on the property. Controlled burning and observation stations will also be allowed.

The hope is that future generations will continue to learn from and enjoy the natural beauty it offers.

Juliana Keeping is a health and environment reporter for AnnArbor.com. Reach her at julianakeeping@annarbor.com or 734-623-2528. Follow Juliana Keeping on Twitter