I’m trying to think of it as seeing more sky. The view to the east of our home changed dramatically this week when a crew took down six mature red oaks and an aspen. Drought stress in recent years was too much for these big trees, which had occupied this land long before we moved here in spring of 1997. If they had been in the woods to the north or west we would have left them, as we have left many others for the pileated woodpeckers and other wildlife that make good use of snags and downed trees. But these were jeopardizing a power line, so they had to go.
The crew was precise and efficient. It took only a few hours for them to take the canopy down in pieces with a bucket truck, fell the trunks, and then stack the logs for neighbor friends who heat with wood. These same neighbors have loaned us their sky for years, giving us space for a small garden on their deer-fenced property just down the road. Going there to water or harvest Roma beans on a July morning can feel like traveling across latitudes into an entirely different climate: cool and shady at our place, warm and sunny at theirs. They have also amended the clay-loam soil over the years with sand and good stuff like pond-bottom sediment and compost. It makes for happy beans. But that’s another story.
At first, the fresh-cut stumps shone like headlights from the still-green grass, scattered with leaves from the surviving oaks. Now they are mounded with fresh snow. A raven gives a gurgling cry as it flies overhead and a gray squirrel sits on a handy new ledge created by a trimmed branch, where a chain-saw smile was left behind for us to enjoy. (We do).
The changed landscape looks fine, but it’s disorienting. How did this unfold, and when? Could the loss have been prevented? And—as on so many fronts these days—there is the question; what next? Do we keep the clearing? The amount of sun and the clay soil are still marginal for a decent garden. Should we try to move in a savanna direction, with native grasses below? Plant oaks in the space, or another native tree species that would be at home in this clay soil? What conditions will they face in the coming years?
Across the state and around the world, forest managers are dealing with these questions on a much larger scale. Still, we’d like to make a thoughtful choice. This is our land at the moment, but it’s also a little piece of a larger local block of forest that supports nesting red-shouldered hawks, foxes, ephemeral ponds used by wood ducks and frogs, and forest interior songbirds like the veery. The hope is that these will be here long after we are not.
I pose my questions to my favorite go-to person on forest ecology, who has often informed my writing on various projects through the years: Dr. Lee Frelich, Director of the Center for Forest Ecology at the University of Minnesota.
Oaks are really good at saving water, says Frelich, with white oak being more drought tolerant then red. They close their stomata (leaf pores) to limit transpiration during heat waves and drought. Their roots go deep. They have an efficient conduction system, every spring adding new wood with wide vessels able to quickly transport soil water when it is plentiful.
That said, he saw more Minnesota oak trees die from drought stress from 2020-23 than he has seen in his lifetime. There was better recovery of trees after two other extreme drought years, 1976 and 1988, because summers were shorter and the following years had pretty abundant rain. But oaks—especially older oaks—are succumbing now due to the combination of multi-year drought alternating with extreme wet periods. Trees in low-lying areas fail to develop extensive fine-root systems during wet periods when the water table is high, only to get caught short when conditions abruptly change. People talk about drought, says Frelich, but climate variability is likely the biggest factor in predicting the direction that our forest communities will take: “The trees don’t know what to adapt to.”
He describes how it happens. Root damage during drought years means that the trees can’t conduct enough water to the canopy, which means they produce fewer leaves, which in turn means that can’t make as much wood or convey food down to the roots. Even if the roots recover, the tree can be lost. “It’s called a death spiral,” says Frelich. It can seem sudden, but it often occurs over a period of years.
Oof. Climate change really hits home when it hits home. (That is, except when you pretend it’s not happening: yet another story.)
Frelich ponders our options for the area where the trees were taken down. “Should you keep the clearing and move to savanna vegetation? That depends on the landform and how much room there is. Maybe more than one cover type would be appropriate. Well-drained hilltops and upper south and west-facing slopes might work well as restored oak savanna with bur, white and northern pin oaks. However, lower parts of slopes or north and east-facing slopes might also support species like red oak, hackberry, basswood and even sugar maple.”
Climate models, he says, show that several decades from now, even for a high-warming scenario, such mixtures in areas with landform diversity and loamy, silty or clayey soils will still be supported, whereas areas shallow to bedrock, and/or with sandy soils that are flat or on very large south/west slopes would probably only support mixtures of drought-tolerant trees and prairie plants.
We shared many memories with these trees. I can see the rings laid down in the years since we moved here in 1997, tightly spaced on the outer edges of the trunk. There are the rings from when our kids were born. There are rings from when they would have been preschoolers in their snowsuits, sledding down the hill toward the frozen pond. (They learned early to roll off their sleds if they were headed for a tree.) I see rings from the years they went off to college, and from all the years they shared with our beloved moms, their grandmothers, who now live on in our hearts. Just this past spring, one of the oaks offered a favorite perch for the broad-winged hawk that was nesting nearby and liked to dive bomb us to be sure we knew who owned the place. Buzzing inches away from our heads, it would swoop up onto a leafless lower branch, glare, and give its shrill cry. We got the message.
Of course, these trees had their own lives, and didn’t exist merely as a reference point for ours. They lived for eighty-plus years after their germination. According to Frelich, canopy-height red oaks in a forest environment often have lifespans more like 150-180 years, with 219 being the record in Minnesota. Certainly, many red oaks don’t live that long, brought down by storms or shaded out long before they reach the canopy. Still, we’ll never know what those additional hundred years might have meant for these individual trees in this particular place: the nests they might have held, the flocks of spring warblers that might have gleaned insects from their branches, the acorns that would have put some fat on the black bears before winter. Next spring, the broad-winged hawk will need to find another perch from which to yell at us.
And so we look ahead, but not without acknowledging the loss. Much as I would like it to be, this is not the process of natural succession that we all learned about in high school biology, nor is it akin to the fluctuation of the prairie-forest border that occurred during warming and cooling periods following the glaciers. We’re finding the limits to nature’s ability to adapt.
For now, the more open view to the east makes sunrise both beautiful to see and hard to watch. Good thing that there’s a brand new year ahead. We’ll need the time; there is work to be done.
