Tom's Blog

Thursday, September 2, 2010

Visit from Sibylla and Bob Brown of Timberhill Savanna

For some years now we have been hearing about the good work that Sibylla and Bob Brown have been doing restoring Timberhill Savanna in southcentral Iowa. We hope someday to make a visit there, but in the meantime the next best thing was to have the Browns visit Pleasant Valley Conservancy. We were able to spend most of the morning with them yesterday on a somewhat drizzly day.

A brief history and details of their management program can be found at the Timberhill Savanna web site. At this 200 acre site, the Browns started restoration work in 1993 and did their first prescribed burns in 1995. By now, they have most of the savanna restored, and burn the whole restoration every year, a major accomplishment.

Their detailed plant list, found on their web site, was developed by Gerould Wilhelm and colleagues with an NRCS grant. Here is a summary of the findings, copied from the PDF file in the web site:

"An initial survey of this area, conducted in June of 2003, discovered 206 native species, which was considered impressive for a single meander inventory over one day. In September that year, 59 species were noted during another day in the field; the mean C value for native species stood at 4.4, with an index of 71. It was becoming more than clear that this area was of great significance insofar as its importance as a Midwestern natural area. Another survey, over two days in July of 2004, revealed another 71 native species, with the mean C value remaining at 4.4 and the index now 80. In the interim period, a significant prairie remnant was added to the property, the floristic elements of which are now included within the overall assessment, although many of the newly added taxa came from the timbered tracts as well. As annual fire is continued as a management tool, it is inevitable that future inventories will add numerous additional species."

It should be noted that all the species in their list arose spontaneously during restoration and burning. No new species have been brought into the site from other locations.

I was interested in the variety of oaks which are present at Timberhill. In addition to the white, bur, black, and red which we have at Pleasant Valley Conservancy, they also have shingle (Quercus imbricaria), and Chinquapin (Q. muhlenbergii), and two hybrids: Bebb's (Quercus X bebbiana) and Hawkins (Quercus X hawkinsiae).

We really enjoyed the Brown's visit, and were pleased that they made the long drive from Iowa to visit us!


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