Tom's Blog

Wednesday, February 10, 2016

A savanna relic: Open-grown oaks at Madison, Wisconsin's Picnic Point

The most common vegetation type in southwestern Wisconsin was the oak savanna, characterized by large scattered oaks interspersed with prairie grasses and forbs. This attractive landscape fascinated early explorers and settlers, who had seen nothing like it in eastern U.S. Because the oaks were so scattered, their lower branches were not shaded, permitting them to continue growing. These oaks are potentially long-lived, retaining their large lower branches as long as they are growing in the open sun.

The tell-tale sign of a former oak savanna today is the presence of trees with the characteristic open-grown character. Once one realizes what an open-grown oak looks like, it is easy to spot them, even if they are now embedded in a dense forest.

It is only a brief walk through the gate and up the hill from the Picnic Point parking area to reach an area with lots of open-grown oaks. In the photo here, taken last Sunday, four or five open-grown oaks can be seen. There are also more on the opposite side of the road.
Five open-grown oaks can be seen in this photo.
They are recognized by the presence of large lower branches, or knobs where branches once grew.

Unfortunately, the oak closest in the photo has lost many of its large lower branches. Only their stubs remain. All these open-grown oaks are surrounded by a dense grove of of smaller trees, not oaks but maples and other so-called mesophytic species.

What did this area look like when these trees were out in the open? It is easy to tell what the area was like about 80 years ago (when Picnic Point was still in private ownership) because we have air photos from 1937 (taken by the U.S. Soil Conservation Service). The first photo below shows the area where the open-grown oaks are now found, and the second photo shows a wider view to put the area in geographic perspective. The open-grown oaks are obvious.

Air photo from 1937 of the Picnic Point Entrance Area
(See photo below for a wider perspective.)

With high-accurate GIS measurements, one could probably relate the trees in the air photo to those still present at the site.
This fascinating view of the Picnic Point Entrance Area in 1937 may be surprising to those familiar
with the area today!

In comparison, the photo below shows the same area in 2010, about 73 years later.

Air photo of the same area in 2010. What happened to the former pasture and
all the open-grown oaks?

In addition to comparing the 1937 and 2010 photos, I have examined air photos for other dates in between. The open characteristic of the 1937 landscape gradually filled in with woods and other woody vegetation. Bill’s Woods, which was a “real” woods in 1937, remained mostly the same, but the savanna area, where the open-grown oaks were so noticeable, gradually became wooded. In 1990, the open-grown oaks still stood out, probably because the invading woody vegetation had not “topped out” yet. But in the 2010 photo it is not possible to see where the open-grown oaks were, or even see where the lane ran, because the woods is dense.

Before 1937, what kept the savanna open, and why did it then close in? The standard explanation, which is undoubtedly correct, is the absence of fire since 1937. Almost certainly this area, as well as most of Picnic Point, was subject to occasional fire, perhaps annual. It is well established that “farmers burned their woods”, generally annually, in order to promote “green-up” of the pasture.

There is a clear fence-line at the bottom of the hill starting at the gate area. We also know from historic photos that cows were pastured on Picnic Point, and there is one photo in this exact area that shows a cow. In 1937 the ownership was in the hands of the Young family, which we know from oral history rode their horses on the Picnic Point lanes. These fields, close to the Young house site, would have been an ideal location for horses.

On September 4, 1935 there was a major fire at the Young house, essentially destroying it. Soon after that the Youngs decided not to rebuild at Picnic Point. Instead, they built a new house in nearby Shorewood Hills. Shortly thereafter, the Youngs decided to sell their holdings at Picnic Point, and by 1939 the University had control of the property. This undoubtedly brought a huge increase in use of Picnic Point. In fact, a caretaker was hired to oversee the site, and he kept careful records throughout each season of visitation. (The caretaker’s yearly journals are in the UW-Madison archives.)

It seems reasonable that there has probably been no fire at Picnic Point since the university acquired the property.

What about the present open-grown oaks? These could be rehabilitated, even without fire, by careful clearing of the understory woody vegetation. This is what has been done to two handsome open-grown oaks in the Frautschi Point area. (A trail from the Frautschi Point parking lot reaches these two oaks.) This sort of clearing is often called “daylighting the oaks”. Bringing in more light to their large lower branches is a very beneficial thing, and in many cases can “save” a handsome specimen.

That would be my recommendation for all the open-grown oaks at the Picnic Point Entrance Area.

Incidentally, these oaks are easier to see now than they will be in summer, when all their surrounding trees have greened up. 

It’s only a short walk up from the Gate, and well worth the visit!


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