Tom's Blog

Tuesday, February 8, 2011

More on Hill's oak

In an earlier post I described some of the information we had obtained about Hill's oak (Quercus ellipsoidalis, also called Northern Pin Oak). Now that we have completed the tree database, I have been able to look at the distribution of Hill's oak using GIS.

The photo above shows the distribution of the different size classes of Hill's oak at Pleasant Valley Conservancy.

There seem to be only two areas here where Hill's oak is present, quite far apart. There are more trees in the group at the eastern end (105; just east of Toby's Prairie) but they consist of primarily smaller trees, although there are a few large ones. There are 49 trees in the group at the western end, at the upper part of the north woods hill, most of which are large sized. Since the trees at the eastern end are at a lower elevation and are close to the woods road, it is possible that the larger ones here were logged sometime in the past.

As I pointed out in my earlier post, Hill's oak is found primarily on dry, sandy sites, and it is lots more tolerant of drought than other oaks. This fits with the character of the soil east of Toby's Prairie, which is quite sandy.

Hill's oak is very shade intolerant and is unable to reproduce under its own shade. It is also well adapted to fire.

Here's what they say in Michigan about Hill's oak: "It’s just a rather rare oak and rarely cultivated to any extent. We have found this oak similar to a good black oak-Quercus velutina. It transplants easy, doesn’t have iron deficiency issues like pin oak and the leaves are very glossy and look great throughout summer. Grows well in well-drained upland soils and on clays and can be found on the borders of lakes and low woods. Wood is heavy, hard, and coarse-grained. Source of acorns for ducks with this species. Height to 50-60 ft. with a 70-80 ft. [root] width. Hardiness -30 °F."

Don't be confused about the taxonomy of Hill's oak. There is another pin oak species, Quercus palustris, that is found south of us, and all through the eastern United States. Taxonomist Andrew Hipp, who has done a lot of DNA research on oaks, calls Hill's a Western Great Lakes endemic.

In future posts, I'll be presenting some more of our tree database data.


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