When I am walking in the woods and see a tree that has fallen, its broken roots sticking into the air in all directions like widespread fingers on an arthritic hand, it is like coming upon a piece of sculpture. I also enjoy the architecture of trees whose trunks have been broken several feet above the forest floor; their diagonal trunks provide a dramatic contrast with the otherwise rigidly vertical structure of forests. After enjoying and photographing these patterns I decided to make a Seeing the Sourlands photo essay on this topic. Then I realized that by concentrating on their aesthetic qualities I had overlooked the ecological importance of dead trees, whether standing or fallen. A healthy forest must include some dead trees.
I decided to broaden the scope of this essay to include both the ecological importance and the aesthetic qualities of dead and broken trees. It has resulted in an ungainly title, but I like the complexity that results from including everything.
The diagonal of this broken tree is the focus for this part of the forest. I was compelled to look at it while I approached and I even looked over my shoulder at it a couple of times when I was walking away.
The remains of this broken tree look like the aftermath of a great explosion. The trunk is about 4 feet in diameter so it’s breaking and then its fall must have occasioned a very loud noise. I don’t know if this is architecture or sculpture but when I came upon it I was thrilled to encounter such a dramatic work of art.
It is common to assume that the death of a tree is a tragedy. The loss of any life is a tragedy of some kind, but if we look beyond the loss of an individual tree to the functioning of the ecosystem we will see that a dead tree contributes importantly to the forest’s ecology. Sometimes the length of time that a dead tree contributes to the ecology is longer than its life had been. A standing dead tree—called a snag—is an important habitat for a wide range of wildlife and it hosts many animals at different links in the food chain. Woodpeckers and other birds eat the insects that are attracted to dead trees and they often make homes in tree cavities. Forty-five percent of North American bird species live in tree cavities for a portion of their lives. Bats roost in cavities. Raccoons and other small mammals live in cavities. Salamanders, a top predator of insects and other invertebrates, live in or under fallen dead trees. Salamanders eat beetle larvae, fly larvae, spiders, sowbugs, roundworms and many insects that consume leaf litter. By eating the consumers of fallen leaves salamanders assure that more leaves will remain on the forest floor, keeping forest soil moist. The preferred home for ants is a dead tree, either standing or fallen. Ants are major consumers of the larvae of defoliating moths, so the dead trees are providing a home for insects that protect living trees. Bees often make nests in tree cavities, and they are the principal pollinators of forest flowers, enhancing the production of seeds, nuts and fruits in the surrounding parts of the forest.
When a tree’s upper branches break the remaining branches or fragments often create a silhouette that is highly dramatic. Did this monster alight from a spacecraft?
Dead trees contribute to forest ecology beyond providing habitat for wildlife. Snags and downed trees shade the forest floor and are a windbreak, protecting the soil from the drying impact of sun and wind. Downed trees slow and divert rainwater runoff, reducing soil erosion and promoting groundwater recharge. They shelter seedlings from deer browse. Decomposing dead trees contribute organic material to the soil, enriching it and making it better able to support new plants and to feed existing plants. There is also a strong relationship between dead trees and many species of fungi. Many fungi thrive on dead wood, decomposing it into material that will nurture the future forest. Mosses, which require some access to sunlight, thrive on the trunks of fallen trees because the logs are above the forest floor and that allows the moss to avoid being covered by fallen leaves. Mosses are habitat for legions of bacteria, protozoa, and invertebrates. If a tree falls into a waterway it slows the current, reducing bank erosion, and it will sometimes redirect some of the waterway’s flow, creating wetlands. Fish and other aquatic creatures shelter under logs that have fallen into the stream just as land animals shelter in logs on the forest floor.
Fallen trees can form visual gateways. These trees draw you into the depth of the scene.
Shadows are an important part of a forest’s aesthetic appeal, particularly that of a winter forest. The partially fallen trees in this view give and receive a shadow pattern that enlivens the scene.
A group of conservationists have formed a not-for-profit organization, The Cavity Conservation Initiative, whose mission is to “promote the safe retention of dead and dying trees.” This looks like a candidate for their protection.