Two trees, about the same size but different ages as illustrated by their growth rings. A similar display in Idaho City labeled the tree on the left “Unmanaged Forests” and the tree on the right “Managed Forests.”
On a recent trip through Idaho City, Idaho, we stopped at the visitor’s center. There I saw a display of cross sections of two different trees exposing their growth rings. The sections were the same diameter, but one tree was 53 years old and the other was 29. Underneath the older section were the words: “Unmanaged Forest” and the other said: “Managed Forest.” Back on the highway, I thought about the dense forests at home and forest management in general. In my 49 years of living in the Tahoe National Forest, the forest has never been so dangerously dense. Dangerous in the sense of fire hazard. This topic is on many minds, and not just in California as the Idaho City display illustrates.
The display is, in my opinion, an oversimplification of a complex issue. Trees that get more sun grow faster than trees that don’t. This is what those two cross-sections confirm. Well-managed forests should be less dense, I agree. Growing up in the woods between Alleghany and Downieville I observed the forest in many conditions. Relatively undisturbed patches of forest are rare, but in those spots the trees are not dense. Old cedar trees scarred by past forest fires tower high. A variety of tree diameters are present, with large diameter trees dominating the landscape.
Most of the forest has been logged multiple times. In freshly logged areas, where the soil is disturbed, tree seedlings sprout in thick patches. If left alone, both brush and trees will sprout in areas of newly exposed soil and sunlight. Other plant varieties that like full sun, such as gooseberries and various wildflowers will also flourish. The brush grows faster than the trees and chokes out many of the tree seedlings. This has the effect of thinning the trees. The trees that do survive within the brush eventually grow taller than the brush. Once this happens the trees gradually choke out the brush. This cycle must take close to 50 years, but I have witnessed it firsthand in the various stages.
We humans are on our own short cycle and it is difficult for us to comprehend these longer cycles of nature. We also have a vested interest in being able to live in or near the woods. In that regard the cycle described above represents many years of increased fire danger, while nature balances things out. While logging isn’t a “natural” form of clearing the forest, fires are. The cycle of brush and tree growth explained above takes place after a fire as well, but with less soil disturbance and the addition of charcoal to the soil. But after fires and after logging the most common “forest management” practice seems to be replanting conifers! This further disturbs the soil and limits plant diversity. After a fire or logging event has taken place, deciduous trees such as oaks and maples have a natural advantage over conifers because their roots don’t die when the top is removed. Without the management practice of replanting conifers, I suspect that deciduous trees would become more dominant in the Tahoe National Forest.
The planting of conifers is for future timber harvests. Timber for lumber is a wonderful thing that creates jobs. Many of us are mortified by the current waste of good lumber trees that are being cleared away from the power lines by PG&E subcontractors. If the timber market was better more people would be salvaging those logs. Some people believe that logging is the best way to manage the forest. I suppose it depends upon what the long-term objective is. In the era before the gold rush, our forests must have been so different!
Right now, we can observe how nature balances things. The high rate of conifer mortality in our area is nature thinning the trees. For us humans, it is frightening to see so many dead trees. Especially when they still have their needles. These are major fire hazards! Others see it as a waste of resources, like the cut trees that PG&E has left on the ground. After a couple of years though, those standing dead trees don’t look so bad, now they are gray totem poles. Many creatures including carpenter ants, termites, owls, woodpeckers and fungi take hold and quicken the dead trees’ fall to the ground. Once on the ground those dead trees continue to feed the forest. Oddly enough, the forest is more healthy with the presence of dead wood than it is without it.