Monday, December 31, 2012

Blue savanna

Part of my job involves managing natural resources.  A pretty big part of it, actually.  Now, 'managing natural resources' means a lot of different things to a lot of different people.  For state parks in Minnesota, it means in part "... to preserve, perpetuate, and interpret natural features that existed in the area of the park prior to settlement ..."

Prior to European settlement, most of southwestern Minnesota was covered in tall grass prairie.  In river valleys and ravines there would be areas of oak savanna, which is prairie with scattered oak trees.  Fort Ridgely State Park is located partly within the Minnesota River valley, and contained areas of both prairie and savanna.  So a good chunk of our resource management involves trying to restore these natural features.

Without fire to suppress their growth, trees and brush have gradually invaded the park's grasslands.  Part of our efforts involve removing these invaders.  Ideally we would do this by re-introducing fire into the system.  Prescribed burning, however, has its limitations.  It won't knock back the bigger stuff, and getting the humidity, wind, staffing schedules and control measures to all cooperate at exactly the perfect way at exactly the right time is very difficult.

So we do a lot of cutting.  Chainsaws, brush saws and brush mowers.  It is painstaking work.  Not only do you have to cut the trees down, you have to decide what to do with the wood.  Small stuff can be left on the ground to rot, but bigger stuff should be hauled away.  And, you need to stop the stump from resprouting next year.  The easiest way to do this is to use chemical herbicide.

We use backpack sprayers to spot treat the cut stumps.  We add a blue dye to the sprayer to mark which stumps have been treated.

Every little small stump needs spraying.  In this picture you can sorta see the minefield of blue branches sticking up out of the ground.  The orange flag on the tree in the foreground marks a burr oak that we are saving, to replicate the scattering of oaks in the savanna.

In the foreground you can see the area we have mowed, cut and sprayed.  In the background is an area we haven't worked on yet, thickly filled with young trees and shrubs. 

Like I said, it is painstakingly slow work.  A crew of four people can work one full day and cover maybe, maybe an acre.  Depending on the types and sizes of trees in the area.  But it is rewarding.  Tall grass prairies and savannas are magical, beautiful places.  They are my favorite places, where a person can go and lose themselves for an moment, an hour, an afternoon.

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