More trees could be the answer to most of the world’s problems.

In the U.S., five foundational species – native oaks, cherries, willows, birches and poplars, with a bit of help from maples – are best at supporting the insects that, in turn, feed all the other wildlife, according Douglas Tallamy.

And I recently attended a lecture in which Ivan J. Fernandez, a soil science professor at the University of Maine who also works with the Maine Climate Change Institute, said that forests are among the best ways to store carbon naturally. It is carbon in the atmosphere, mostly as parts of carbon dioxide and methane, that is causing the world’s climate to warm.

Maine has set a goal to be carbon neutral by 2045. Steps toward that goal are to reduce carbon emissions, with 1990 as the base year, 45 percent by 2030. Being carbon neutral would mean that all of the carbon released into the atmosphere would equal the amount of carbon being stored in nature over the same time. About 90 percent of released carbon comes from burning fossil fuels for transportation, heating buildings and manufacturing, Fernandez said in his lecture, which was co-sponsored by the Coastal Maine Botanical Gardens and the Maine Landscape and Nursery Association. The rest comes from deforestation, mostly the destruction of tropical forests.

That released carbon dioxide is stored in several places. About a quarter of it goes into the ocean, which contributes to the acidification of the seas. About 25-30% goes into forests and soils. The rest goes into the atmosphere, which is causing the rising temperatures of climate change. Some of the progress toward carbon neutrality would be achieved by making more efficient use of fossil fuels.

Fernandez’s focus, however, was on natural carbon solutions, which he defined as “any action that conserves, restores or improves the use or management of forests, wetlands, grassland and agricultural lands, while simultaneously increasing carbon storage or avoiding greenhouse gas emissions.”

Overall, Maine is doing pretty well, especially in carbon storage.

“The world wants to be Maine,” Fernandez said. That’s because Maine is almost 90 percent forest, more than any other state, and forests are the best places to store carbon.

That storage, I was surprised to learn, is not mostly in the part of stately trees you see while hiking through the woods. “There is two to three times as much carbon below the ground in the soil than you see above,” Fernandez said. The underground storage includes the roots and the carbon in healthy soil.

For carbon sequestration, which is the amount of carbon actively being removed from the atmosphere, Mississippi is way ahead of Maine. That is because most Mississippi forests have been clear-cut and replanted. Young, rapidly growing forests take up carbon more quickly.

The carbon-holding capability of the Maine forests won’t last forever. The owners are going to cut the trees and sell them. In good forestry practices, the cut trees will be replanted, which will sequester more carbon, but it will take decades to sequester as much carbon as was held by the large, cut tree. If the wood goes to houses, carbon can continue being stored for 100 years. For paper or cardboard, the carbon is back in the atmosphere in a year or two.

Fernandez stressed the importance of soil in the battle for the climate. Soil is a living thing. Small plants and animals thrive in it, and carbon and other nutrients support above-ground plants. Soil is generally considered to go about two yards below the surface, but because of ledge it often is shallower in Maine. While organic matter is at its highest percentage close to the surface, soil two yards down does contain organic substances.

If soil is so important, how should you preserve it? Mostly, never leave it naked. If you aren’t actively growing something, add a cover crop or use mulch such as leaf mold. If you are growing something, plant a variety of plants, not all just pines or potatoes. Using no-till garden methods also keeps the soil healthier.

Perennial plants conserve soil better than annuals. But that doesn’t mean you can’t grow vegetables and annual flowers. Just keep the garden well mulched.

You should reduce tillage, which damages organic matter. Have buffers at the edge of fields to prevent heavy rains from washing away the good topsoil. Use heavy equipment on the soil as little as possible, especially when the soil is wet.

And Fernandez said several times: All you are doing with the soil to sequester and store carbon does not give you permission to burn any more fossil fuels than absolutely necessary.

Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at: tomatwell@me.com

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