Climate curious: What are the best carbon-capturing trees to plant?

Fall colors in northern Minnesota
Colorful maple leaves contrast against a birch tree in the background on Oberg Mountain near Tofte, Minn., last year. Forestry expert Eli Sagor says planting a variety of fast-growing trees, like maples and oaks, can help contribute to the fight against climate change.
Andrew Krueger | MPR News file 2018

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What type of trees are best to plant in our region to capture the most amount of carbon? We have a small hobby farm and we have the ability to plant some trees, and I'm just wondering what the best kind to plant are for our region.
— Mike Larson, Ellsworth, Wis.

Trees can help address climate change because they take in carbon dioxide and store it. They can absorb as much as 20 percent of our annual greenhouse gas emissions.

But which trees do that best?

Eli Sagor, a University of Minnesota Extension professor at the Cloquet Forestry Center, said it kind of doesn’t matter.

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Wood, he said, is good. And that’s the main thing to keep in mind.

Choose fast-growing trees

When trees pull carbon out of the atmosphere, they store it as wood. So if you’re trying to figure out which trees to plant on your property, consider a fast-growing tree species, like maple, oak or catalpa.

Beyond the specific species that tend to grow faster than others, it gets pretty complicated to figure out which trees will grow the fastest in a particular area. That depends on a lot of factors: soil, site conditions, local climate, etc.

So, a tree that might do well in southern Minnesota might not do so well farther north. Other factors might include how well you're able to care for a tree, such as keeping hungry deer away from it.

Evergreens photosynthesize — take in carbon from the air — more months of the year than other trees. Because they keep their needles year-round, they can continue to photosynthesize until the ground freezes.

With longer growing seasons that are a product of climate change, Sagor said, it’s likely that evergreens are taking in more carbon than other trees in the early spring and late fall. But they don't capture carbon in the winter, and it’s still important to keep in mind all those other factors that affect how well a tree grows.

Plant a variety of species

When you’re considering which trees to plant, Sagor says not to focus too much on a single species.

There can be some danger in planting a single kind of tree: One look at the ways the emerald ash borer is gradually attacking all of Minnesota's ash trees right now explains why.

Sagor said he tells landowners instead to focus on keeping trees healthy. And if you own woodlands, thin the trees periodically to give them enough growing space to keep growing fast.

Use the wood you harvest

Sagor also said that, if you’re really concerned about carbon emissions into the atmosphere, it’s also best to use the wood you harvest, if you end up cutting down trees.

Turning trees into lumber instead of leaving them to the elements prevents them from decomposing, which adds some carbon to the atmosphere.