The other morning was a bit foggy and I felt that might aid my efforts. So out I went, armed with my camera and tripod. Here is one of the shots I got by placing the camera maybe 18 inches off the ground and on one of the upslopes leading to the tree.
Disappointing, really. Here the tops of the trees in the background are still showing, detracting, I think, from the effect I was looking for. Setting the aperture at a narrow f/16, I tried to bring the foreground plants into the composition. But frankly, they just aren't very interesting and don't provide any sort of focal point.
Here is another shot I took, in portrait format, in which I succeeded in eliminating the background trees.
Again, I had attempted to bring the foreground plants into the shot as a point of interest, but there just wasn't anything there to work with. As a consequence, the shot is just too simple.
So then I decided to step back and essentially accept the line of background trees, and frankly the results were quite a bit better, I thought. Here are a couple of those shots, taken in portrait and landscape.
I had noticed some dark swales running through the foreground and felt that they might provide the point of interest that I was looking for. To the extent these shots work I think it is because of those swales. Although the modest amount of fog created a bit of separation between the oak and the trees in the background, more fog would have helped.
By the way, when I had initially arrived at the site, there were a number of turkeys cavorting in the field near the oak. They all decamped as soon as I got out of my car. And it turns out that the small brownish patch that appears under the right side of the oak's canopy in the above shots is actually a turkey blind, complete with decoys and chairs for the hunters.
So here perhaps is the lesson that I took away from this. In composing landscape shots, foreground can be just as important, perhaps more important, than background, and even though the primary subject may be in the background, it is important to establish a point of focus in the foreground to provide context and depth.