Researchers in Chicago are beginning a study Tuesday that they hope will extend the life of urban trees.

All those trees you see lining shady Chicago sidestreets actually have it pretty rough. Their average lifespan is less than ten years. That’s compared to fifty or sixty years for their suburban cousins.

Bryant Scharenbroch is a soil scientist with the Morton Arboretum. He said all those city roads and buildings make soil too dense.

“When you compact the soil to make it suitable for infrastructure, you’re also making it kind of a hostile environment for trees,” he said.”

So scientists are testing out biochar, a sort of super-heated charcoal made from plant matter. Ancient Amazonians were using biochar on their crops centuries ago, but its affects on trees haven’t been widely studied, said researcher Kelby Fite, with Bartlet Tree Experts.

Biochar adds nutrients into the soil, like compost, but lasts a lot longer.

“So compost may degrade in a matter of a handful of years, whereas biochar could be stable for hundreds, or even thousands of years,” Fite said.

The researchers will monitor sample trees in the Bucktown neighborhood for the next couple years.