Baldwin’s land: the foresters’ soil solution

Baldwin sits at the convergence of two different worlds, at least from a soil perspective. This drastically affects the vegetation that is native and will thrive over time.

Most of the township sits squarely in the Anoka Sand Plain, with a small piece in the southeastern corner along Sandy Lake in the Elk River Moraine.

What plants are native to the Anoka Sand Plain is a point of contention between foresters like Steve Nelson, who allege the soil composition calls for young forests and small plant specialists, like Prairie Restoration's Josh Richardson, who claims prairie grasses are native. I discussed the prairie side of the argument in a post last week.

"The trouble is is that nobody had ever identified where the [prairie] oak savanna was in the Anoka Sand Plain," said Nelson, and it turns out none of it is in Baldwin Township.

In fact, according to recent soil samples of the 650,000 acres of the Anoka Sand Plain only 5% is prairie oak savanna and all of it is along the edge of the plain.

This is because the Anoka Sand Plain is the refuge from what was once a string of glacial lakes that pushed coarse, heavy sand to its shores, depositing lighter, fine sand in its center as it dried out. The coarse, sandy soil is known as mollisol among soil specialists; the fine sand that encompasses the majority of Baldwin is called entisol.

The piece of Baldwin in the Elk River Moraine is comprised of Alfisol, or old forest soil, which is also more suited to trees than prairie.

From there, the argument becomes simple for foresters: soil type depicts the vegetation that belongs within it.

Mollisols are a mix of coarse sand and organic matter in which prairies are meant to grow. The organic matter is renewed by wildfires or controlled burns, which help prairies restore themselves.

Entisols consists of basically nothing but fine sand and are only suitable for young forests. They do not benefit from controlled burns.

This seems like just a battle between academics until you consider what is at stake -- millions of tax dollars that have been spent over the last 20 years to restore prairie oak savanna throughout the Anoka Sand Plain in many places where Nelson says it never belonged in the first place.

And doing so in places such the Sherburne Wildlife Refuge -- which is comprised primarily of entisol soil -- has led to an increase in oak wilt disease that Nelson contends threatens native trees in other areas within the state.

The oak wilt problem is compounded by several factors. Natural Oak Savanna is comprised of a variety of oak types, but burning entisol soil that contains a variety of oak seedlings kills the seedlings. Then, as northern pin oaks are replanted, the non-native oak savanna becomes dominated by one type of tree, otherwise known as a monoculture. This monoculture is more susceptible to disease, especially once the bark of its trees have been scoured by fire.

Instead of controlled burns in these areas, foresters like Nelson recommend passive oak wilt control.

"This sounds like letting nature take its course, but it actually means speeding up nature taking its course via harvesting, usually up to a cover type change," Nelson writes.

When it comes down to it, foresters like Nelson are simply arguing that restoring prairie where it doesn't belong is not sustainable. Native prairies should renew themselves overtime, but prairies planted in entisols will not.

What plants does he recommend for Baldwin's open spaces, as well as the average resident looking for sustainable plants for their backyard?

The majority of Baldwin is well suited for mixed oaks, hardwoods and conifers such as red, jack and white pine, as well as red cedar forest.

The Southeastern corner near Sandy Lake is well suited for mixed deciduous and coniferous trees, such as quaking aspen, spruce, white pine, basswood, sugar maple, northern red oak and balsam fir.

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