As Flint tries to survive and thrive as a smaller city, the thousands of abandoned homes and vacant lots scattered throughout its neighborhoods are more than a reminder of its past as a manufacturing boomtown.

They're a costly headache to keep from getting wildly overgrown, with grass that can grow several feet high before being mowed.

Grass experts, sociologists and community leaders have teamed up on a three-year project to cut some of that grass and try to test the idea that maintained lawns and parks help revitalize neighborhoods. Lessons learned in Flint, they hope, could be used around the country.

"At one of the areas we're looking at, there's basically a park but no one is playing in it," said Thom Nikolai, a Michigan State University turfgrass specialist who is leading the study. "We want to come back in a year and see people throwing a Frisbee around."

Flint's population has fallen to about 115,000 from a peak of about 197,000, leaving behind many crumbling neighborhoods. Emblematic of the industrial decline across the Rust Belt as auto plants closed and more than 89,000 General Motors jobs there dwindled to about 6,000, researchers want to see the economic effects of improving lawns and parks.

Stephen Gasteyer, an assistant professor of sociology at Michigan State, said researchers plan to measure what effect lawn and park improvements have on neighborhoods. And they want to learn more about how community groups, for example, keep up vacant land and abandoned homes.

"One of the realities, at least for the time being for places like Flint ... is that private investment to turn around a community, with all its discontents, is not likely to be an option," Gasteyer said.

Researchers began work last month at the site of a former convalescent home. A "turf garden" likely will be grown there to allow researchers, government officials and the public to see how different types of grasses look and whether kinds that grow slower might ease the upkeep of vacant lots.

Another test site will be around Ramona Park in the Metawananee Hills neighborhood, which is peppered with vacant homes but described by residents as stable. Members of the neighborhood association in recent years have cut grass at the park when the city didn't, and they'll volunteer to mow other yards throughout the area.

"We want to see if it's going to be contagious," said David L. Caswell, 68, a retired school principal who has lived in the neighborhood for more than four decades and is a member of the association.