Sunday, September 6, 2009

Woody Brush Removal

This spring, Dad and I signed up for and received a grant from the Minnesota DNR for woody brush removal. It is part of the Landowner Incentive Program (or LIP). For us to keep a true native prairie, we need to keep brush and trees out. It provides financial help and expert advice on how to keep our prairie - a prairie - and not let it turn into woods.

No matter how much I like trees shading my house, they do not belong on the prairie. Over the years and through the centuries, the boundaries between forrest and prairie would shift... brush and trees would grown and spread slowly into prairie territory. Then fires would beat back the trees and allow the prairie to take over again. Once white settlement came and divided the prairie into smaller and smaller pieces by building roads and tilling the soil, the major fires ended. No more would fire restore vast acres of prairie.

So those of us blessed with the responsibility of caring for a tiny piece of prairie do our best to maintain the native species. The fires we have had the last 2 years are a major part of that management. The burns were very successful in that the prairie species are thriving.

UNFORTUNATELY, the quaking aspen trees increase after fire. Quaking aspen, and to some degree cottonwood trees are spread by cloning. That is they send out baby plants from thier roots. The quaking aspen rarely grows from seed. Each tree is either male or female, and most large stands are all the same gender - in fact they are the same plant. There is a stand of quaking aspen in Utah that is considered to be the largest and oldest organism in North America. Each tree is part of the same plant and is genetically identical.

That brings us back to our problem. The fires killed some of the quaking aspen and damaged others, but before they died, the roots got the message to grow more trees ASAP while there was still nutrients available in the roots. And grow they did. We have 3 foot aspen trees all over the place! The cottonwoods spread too.

What to do? Repeated burns may help, but we can't burn every year... cutting the tree causes the same "grow now!" message to get sent to the roots...

So, we enlisted the help of the Minnesota DNR and Heartland Conservation Services and are following the recommended treatment. Heartland is chemically spot treating the little shoots. They are using 2 different approaches. Where the shoots are farther apart, each little tree is getting an individual dab of poison at its base. The ones that are packed in close together are getting 'wiped' with a poison filled custom weed wipe. It is a PVC pipe wrapped in canvas. The pipe has small holes to let the poison soak into the canvas. A valve controls the air flowing into the pipe, which controls how much poison gets to the canvas. It does not drip onto the ground, but keeps enough liquid on the canvas, to apply to the leaves of the tiny trees.

This fall, we will "girdle" the larger trees. Girdling involves stripping the bark all the way around the tree. The strip only needs to be a few inches wide, but it has to go all the way around. This will kill the trees without telling them. That is this fall, the nutrients will still flow through the inside of the tree to the roots, but in the spring, the water and nutrients won't be able to flow up the bark to the leaves.

We appreciate the DNR for their assistance with this project.

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