Tom's Blog

Thursday, April 2, 2009

Planting recently burned oak savanna

Yesterday we planted a mix of savanna species on the bur oak savannas on the upper part of our south-facing slope. We had a great burn here two weeks ago and finally found the time to get the seed mixes ready. The photo above shows a view of this area.

What we call an open savanna seed mix has over 100 species, and in addition to forbs includes prairie grasses such as Indian grass and side oats. The idea is that depending on which side of a bur oak a seed falls, it will be more or less sunny. On the sunny side, prairie grasses may brow, whereas on the shadier side will be savanna forbs.

I'd be happy to send anyone interested an Excel spreadsheet of our 2008 seed list.

Susan and Marci did the planting, and the wind was great so that the seeds got well spread.

After they finished, Kathie planted some of the same areas with savanna (cool-season) grasses. These are not planted as a mix, but each species is planted separately, in swaths. The idea here is to have a patch here and there of a single species. This not only looks nice, but is actually the way these species are found in nature.

We have planted this area several times before, but experience has shown that not every species gets started every year it is planted. Repeated planting is a good idea. And we always plant just after a burn, when the ground is bare.

The south-facing slope at Pleasant Valley Conservancy is actually a composite of two separate vegetation types, a short-grass prairie on the lower slopes, and a bur-oak savanna on the upper. I think the reason for this division is because of the topography of the site. The lower slope is very steep and gets the full brunt of the sun, especially in the spring and fall when the sun is still at a fairly steep angle. (I have calculated that at this time of year a 45 degree slope gets about 60% more sunlight per unit area than a horizontal surface.) The upper slope, as the photo here shows, is not so steep, and is leveling off. This is where the bur oaks are.

If you want to see this bur oak savanna well, take a walk along the south fire break, which you can reach from our service road. The management map on our web site shows where this is. It's a great walk and takes you through the heart of this bur oak savanna. This walk can be done any time of year, because the great oaks are always nice to see.


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