Tom's Blog

Sunday, February 17, 2013

Identifying restorable bur oak savannas

In the 1990s there was a flurry of interest in oak savanna restoration. In 1993 the Environmental Protection Agency funded a symposium/workshop on oak savannas. The next year there was a symposium on Barrens and Savannas at Illinois State University (Normal, Ill.), also partly funded by the EPA. Then in 1995 EPA funded a meeting in Springfield, Missouri which led to a publication called the Midwest Oak Ecosystems Recovery Plan: A Call to Action. Finally, in 1997 another Midwest Oak Savanna and Woodlands symposium was held at the UW-Madison Memorial Union.

It was just at the time of the 1997 meeting that Kathie and I made our first steps toward restoration at Pleasant Valley Conservancy. We benefited greatly by having been contacted by Brian Pruka, who had been one of the important contributors to the 1995 conference. (Pruka's well-known list of savanna indicator species was published in the 1995 book.)

Looking back at the 1995 Recovery Plan, I see that we had lucked out. We had a classic Northern Bur Oak Opening: "Quercus macrocarpa-Quercus alba-Quercus velutina/Andropogon gerardii  Sparse Woodland, more often referred to as Oak Opening, is a dry-mesic to mesic community that commonly occurs on level to moderately steep, fire-prone landscapes in...southern and western Wisconsin.... Canopy cover ranges from 10-30%. The groundlayer is dominated by graminoids, especially Andropogon gerardii and Schizachyrium scoparium, accompanied by a large diversity of forbs.... Understory species typical of oak openings require some direct sunlight throughout the growing season and are quickly reduced when heavily shaded by either tree or shrub canopy. Common shrubs in this community are adapted to the moderate fire frequencies found in oak openings, and resprout vigorously after burning."

Other groundlayer species that the Recovery Plan said might come back after restoration were: " Upland Boneset (Eupatorium sessilifolium), Purple Milkweed (Asclepias purpurascens) ... Cream Gentian (Gentiana alba), Yellow Pimpernel (Taenidia integrima)," all of which are now flourishing at Pleasant Valley.

The Recovery Plan was also optimistic that Wisconsin might have a lot of restorable bur oak savannas: "[In Wisconsin] it is anticipated that...Oak Openings might still be found in the 'Driftless Area' of southwestern Wisconsin. This region has many narrow, untillable ridges, steep topography and a pre-WWII history of fire use by landowners that may have enabled the persistence of small, recoverable, moderate quality Oak Openings."

In southwestern Wisconsin I have seen quite a few sites where large open-grown bur oaks are present. The photo below is an example, showing what foresters call a "wolf tree". 

The point of this post is to encourage landowners who think they might have promising properties to contact the Blue Mounds Area Project and request a survey by the resident Ecologist. For further information, check the BMAP web site.

Wolf tree in a southwestern Wisconsin woodlot, an indicator of a potentially restorable savanna.


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