A Tree Falls in the Forest
Puddock Hill Journal #108: I’m thankful for a rotting log.
May I take this moment to express thanks for something dead?
Last week, we returned from some time away to find that an old snag in the east woods had fallen to the ground to become a rotting log.
What I refer to as the east woods is a narrow band along the fence line in that direction, no more than fifty feet deep (although in one part it borders a neighbor’s wooded area). But one section, perhaps a quarter acre, goes all the way to the stream.
To call it woods is more aspirational than descriptive. There were some old, tall trees there when we acquired the property but no understory besides invasives, which we removed. I have been gradually encouraging it to become more thickly wooded, but there’s just enough shade that saplings grow slowly.
On the eastern-most edge, we planted tuliptrees, dogwoods, shagbark hickories, magnolias, redbuds, and a few other tree species. These have been joined by a number of volunteer sassafras and tuliptrees, but as one moves west there are fewer self-seeded saplings. To compensate, for the past couple years I’ve been transplanting appropriate native volunteers from various beds. Last year, this included a pair of pin oaks. This weekend, I relocated to this burgeoning woods four small tuliptree saplings from the beds on the bridge, a larger year-old tuliptree from the natural area by the house, and an American beech that had found its way into a bed in the front lawn.
There are now 15 or 20 very young trees in that woods marked with stakes (so we don’t inadvertently kill them with the string trimmer), fighting for light under some mature tuliptrees, black cherries, box elders, and sycamores.
And now there’s a rotting log—an essential part of any woods.
I have written before that a healthy forest contains two and a half dead standing trees per acre. These snags support wildlife, especially woodpeckers, other birds, arthropods, and small mammals. When they fall—as they eventually must—their contribution to the life of the forest continues, which is why I welcome this newly fallen log:
Like all trees, when all is said and done this one will have undergone decomposition in two ways: first while standing and second while lying down. That may be obvious, but scientists are still studying the contributions dead trees make to the forest.
An article in Scientific American focuses on the scientist Mark Harmon of Oregon State University, who’s been studying tree decomposition for forty years and who I suspect inspired a character in Richard Powers’s novel The Overstory. The process of decomposition, the article notes, “influences the long-term productivity and biodiversity of a forest.” Without decomposition, there is certainly less biodiversity.
Ecologists like Harmon are exploring questions such as: “How does temperature affect the activity of decomposers such as brown rot fungi on various wood species? How do changing ecosystems promote or hinder interactions among invertebrates, microbes and wood? At what rate is carbon released from downed wood? This last one is of particular importance because it affects nutrient cycling through soils and roots, as well as climate change.”
Different species of trees decompose at different rates, and the fallen snag in our east woods (which I think is a boxelder maple) seems to be going fast, already largely hollowed out before it fell. Here’s a closer look:
Everything has a role in natural systems. A fallen tree’s job is “boosting biodiversity by providing habitat and returning carbon and nitrogen to the soil.” The forces that do this work include water, solar radiation, insects, and specialist fungi.
In the Northwest forest where Harmon has focused his research, deadwood “might remain on a forest floor or stand upright as a snag for anywhere from three to 750 years.” That’s an astonishing range, but I suspect my little log will disappear sooner rather than later.
A dead tree, Harmon says, “is just a transition to something else.” And nature—even in healthy ecosystems—is ever in transition. In fact, I don’t think I’ve ever walked through a forest without seeing trees uprooted by storms or logs on the ground in various states of decay.
So, paradoxically, this one small log in our east woods is, to me, a sign of forest growth. In a landscape once degraded, the cycle recovers itself, now with a little help.
In tightly settled suburbia, trees get cleaned up and hauled away, rarely left to rot in place. I’m grateful to have the freedom to leave this dead tree where it lies.
May it feed the critters and the soil and the saplings.
Fall in the patio garden with native Amsonia hubrichtii ‘Butterscotch’ bracketing the steps:
