Amputations and Restorations
This old bur oak shows its battle scars, its progeny and some quandaries.
Before we cut the tall invasive trees away, the three dead limbs on the right were completely hidden. Over decades, those three now-leafless limbs had been shaded out, essentially amputated, by invasive trees.
The now-dead limbs grew at a time when this tree had ample light on that side -- perhaps one or two hundred years ago. Now new lower branches are growing where the invasives had been.
This summer great-crested flycatchers and yellow-throated vireos sing from these branches. These birds of conservation concern have repopulated the more open woodland these last few years. The ancient oak may thrive another hundred years, but it won’t last forever. Will another spreading majesty replace this one? What of all those skinny pole trees behind it? They will never be such. We agonize over what to do with them.
Lake County Forest Preserves ecologist Ken Klick suggested thinning. Some axe work is one good thought. But how do we decide which should go? In any case, we’ve been following another approach, perhaps not the best? We’ve imagined that repeated burns might do the thinning nature’s way, and favor the more fire-adapted individuals. But a highway is close, downwind of this grove on most burn days, so the burns are muted, and few oaks have been thinned that way.
We love hickories, but we also know that they can be overabundant to the point of inhibiting the bur oaks that are the backbone of this ecosystem. We could cut most of the hickories and some of the oaks, as we’ve done elsewhere.
Indeed, one of our principles has long been to thin sufficiently so that the old canopy species can reproduce. Here, in Circle Grove, all the really old trees are bur oaks. They stand around the edge, in a circle. The inner giants may have been cut because they were straighter, or bigger, or they may have died because they were older, or some other history may apply.
In the foreground of this photo, the many bronzy leaves are the tops of young bur oaks. There’s plenty of opportunity for young trees to spread and grow here. Yet these trees are mixed with tall grasses, and the fires burn off their tops every couple of years. They have to start over after each fire. Should we isolate this area from the fires for a few years until the grasses get shaded back and the oaks get big enough to withstand today’s milder fires?
So many questions. Most of them we don’t bother to answer, because there are so many varied conditions even on this 83-acre site that most ‘experiments’ are being performed naturally – and we have only so much time to help. New oaks are indeed becoming sustainable trees in many places.
Yet, if we had time, we’re eager for our work everywhere to be the best, and we need to set priorities. What would you do here?