Tom's Blog

Monday, January 11, 2016

Oak savanna restoration: before (1997) and after (2014)

I'm putting together a PowerPoint presentation on "Fire Management in Oak Savanna Restoration" for the Prairie Enthusiasts annual meeting next month and this has prompted me to delve deep into my computer memory for suitable photos. The two photos here represent striking "before" and "after" shots at a well-known location at Pleasant Valley Conservancy.

The tree we call the "big bur oak" is right across the driveway from the PVC service entrance and is very visible from the road. This is where Kathie started the first restoration work back in 1997 (19 years ago). At the time the 1997 photo was taken, the area in front of the tree had been cleared, but the area behind and up the hill all the way to the top was still a dense infestation of buckthorn and honeysuckle, along with many large trees (slippery elm, cherry, box elder, black oak) that were later removed.
The "Big Bur Oak" on Oct 18 1997, after the first clearing work had been done.
The density of the shrub layer behind the tree was typical of the whole property.

Burns began as soon as the slope was clear. The photo below shows Kathie burning the lower part of the south slope in early April 1998. Note all the brush still remaining on the upper slope. This was removed in the winter of 1999 (see photos below).

Most of the restoration work on the upper slope was done in the winter of 1998-1999 by Paul Michler and Willis Brown (shown in the photo below). The steep hill made work difficult. Most of the large trees were cut into sections and rolled to the bottom where neighbors removed them for fire wood.

Once the whole south slope was cleared we started burning it. Initially there was not a lot of fuel so burns were spotty, but as the years went by the burns got better. The first year that the whole south slope burned readily was 2002. Since then there has been no trouble getting the slope to burn.

Every year since 1998 the area around the big bur oak has been burned. Since the oak faces south, the front of it gets lots of sun, so warm-season grasses are now well established.

The photo below, from 2014, shows how lush the area now is.

Compare the branches on the 2014 photo with that on the 1997 one. Note that all the branches present in 1997 are still present and that they are alive. Because of the topography, it is possible to walk up to, touch, and examine the lower branch on the west side of the tree.

As soon as the area around this bur oak was cleared it was planted with a complete seed mix. However, the first two years nothing grew, due to the toxic compounds that were left in the soil from the buckthorns. We persisted, and since the third year good growth of native plants has occurred. 
Note also that the principal vegetation is now warm-season grasses, primarily Indian grass. However, several years ago I did a complete inventory of the vegetation around this tree and found over 20 species of native plants.

Unfortunately, for many years after clearing we continued to have small buckthorn plants arising from dormant root stock. These have been routinely treated with herbicide and since about 2012 have not been a problem

Two other invasive plants that we have dealt with in front of this bur oak have been sweet clover and smooth brome. The latter was taken care of by early spring spraying with glyphosate. After spraying we planted a good warm-season grass mix.

Sweet clover has been harder to eradicate. In the early days, the rather dense patches that developed were mowed with a brush cutter at the time of flowering. In later years hand pulling was used. Although sweet clover is still scattered on the south slope, we have eradicated it around the big bur oak.

This big bur oak represents a microcosm of what has been done all over the Conservancy. It is gratifying to realize the great progress we have made. at Pleasant Valley Conservancy. And it only took about 20 years! 


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