In the future, we may be able to farm trees in a much more sustainable way — by paying attention to the microbes that grow in forests. A new study reveals which forests can be farmed without the risk of releasing more carbon dioxide into the atmosphere.

How To Know Where Cutting Down Trees Will Do The Least Damage

A group of Yale researchers wanted to know how deforestation was affecting vast communities of microbes that live in forest soil. These microbes, perhaps even more than trees, are crucial for regulating levels of the greenhouse gas CO2. Drastic changes to those communities, such as those that follow deforestation, can allow more CO2 to escape into the atmosphere and exacerbate global warming.

After collecting soil samples from 11 distinct U.S. regions, from Hawaii to northern Alaska, the researchers found that the texture of the soil was the critical factor in sustaining this microscopic ecosystem. Muddy, clay-like soils provide the most stable environment, probably because they're better at retaining nutrients than loose, sandy soils.

"We were astonished that biodiversity changes were so strongly affected by soil texture and that it was such an overriding factor," says Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry & Environmental Studies. "Texture overrode the effects of all the other variables that we thought might be important, including temperature, moisture, nutrient concentrations, and soil pH."

Perhaps most surprising, the researchers also found that microbial communities could continue to thrive in areas where trees had been cut down two centuries ago.

"The effects are consistent, no matter how long ago deforestation happened," Crowther explains. "In a clay soil, you cut down the forest and the nutrients are retained for long periods of time and the community doesn't change. Whereas in a sandy soil, you cut down a forest and the community changes dramatically within only a couple of years."

This information could help people choose which forests would be best-suited to farming and replanting. Some forests, especially those in sandy soil, should probably remain untouched.

Read the full scientific study in Global Change Biology.