Sustainable forestry practices that don’t kill trees

Forestry work in Austria

Sustainable forestry seeks to use the resources of a forest in a way that maintains the health of the forest. For the most part, it means finding ways to cut down trees selectively. As it turns out, though, it can include the use of at least three ancient techniques for harvesting lumber without killing trees at all: coppicing, pollarding, and daisugi.

Forests have great ecological benefit in sequestering carbon and providing habitats for diverse wildlife. The way to achieve maximum ecological benefit, then, is to leave the forest alone except, perhaps, for recreational use.

But forests also have great economic benefit. Throughout human history, wood has served for fuel, construction, and what we now see as consumer goods. That is, I can’t think of a good overall term to encompass the kinds of tools, toys, paper, and decorative items people made from wood long before anyone thought of consumerism.

Nearly 1.6 billion people now rely on forest resources to live. The worldwide economic values of forests amount to twice the GDP of the US, or about $33 trillion annually.

Bad forest management eventually ruins the viability of a forest. It takes out more trees than new planting can replenish. That is, if indeed new trees are planted at all. Sometimes people clear cut trees to mine minerals underneath or to plant crops that seem more valuable.

We have no good statistics on forest loss. I have seen one estimate that the earth loses about 32 million acres of forest every year. That amounts to about an acre per second! Deforestation too often results in severe erosion. That makes it impossible for the land to sustain much of any life at all.

Basic principles of sustainable forestry

Fall colors in Allegheny National Forest, 2019

Sustainable forestry begins with understanding the specific character of each forest. Practices that greatly enhance one forest may harm another. Therefore, the first step in sustainable forestry practices is to survey the forest. Take an inventory of what kinds of trees it contains.

Not only that, but inventory all the other animal and plant life it supports. Take note of any endangered species. Also, take note of watersheds, wetlands, kinds of nearby development, cultural heritage, and recreational uses.

Only then can forest managers determine what they can harvest from the forest and how much and maintain the health of the forest. Cutting down older trees can encourage diversity and new growth. When trees grow too close together, thinning them promotes healthier growth of remaining trees.

For every tree cut down, sustainable forestry demands planting at least one other tree. And not only that. Since monocultures are inherently not environmentally healthy, it’s necessary to plant a diversity of trees that will fit into the forest’s ecosystem and provide the desired timber years down the road. After all, trees die naturally every year. Forests have a way of regenerating themselves. Sustainable forestry practices follow these natural patterns as closely as possible.

Cutting down entire trees is not strictly necessary to get lumber. Careful and selective pruning can provide lumber and leave a living tree. But at least three ancient practices go beyond pruning and, in some ways, provide superior lumber from living trees.

Coppicing and pollarding

Coppiced trees in Stanmer Park, England

The ancient technique of coppicing takes advantage of the fact that new sprouts arise from the stump of a felled tree. Written record date back to 1251, but archeologists have found evidence of the practice in Neolithic times.

Coppicing was very important early in the Industrial Revolution. It provided the charcoal needed to operate iron smelters and the tanning liquors for making leather. Once other fuels replaced charcoal, coppicing declined rapidly.

Nowadays, homesteaders use it to provide firewood, fencing, and handles for tools.

Any broadleaf tree can be coppiced. It rarely works with conifers. Some coppiced trees are stronger than others. Ash, hazel, lime, oak, sweet chestnut and willow work especially well. Many stools emerge the first year after cutting, but as with trees that grow from seedlings, only the strongest survive.

In some species, sprouts can grow a meter in length in the first year. Growth slows dramatically beginning in the third year. Depending on the species, these stems can be ready for harvest as soon as seven years or take as long as 35 years.

The stump can survive coppicing for hundreds of years. In fact, since coppiced trees remain in a juvenile state and never reach the height of mature trees, they can live even longer. For one thing, they’re less susceptible to being toppled by strong winds. Diseases have less chance to take hold.

Pollarded horse chestnut

On the other hand, browsing deer and cattle can easily destroy coppiced trees. Managers of coppiced woodlands must build fences or otherwise actively protect them.

Pollarding is a technique similar to coppicing, except the cut is made eight feet or so off the ground. Such a tree is called a pollard. Grazing animals can’t harm pollards, so they are compatible with pasture land. Since pollards can coexist with cattle, the same land can yield both meat and wood.

In modern urban areas, pollarding can keep trees out of the way of utility lines.

Daisugi

A similar but somewhat different technique, daisugi, developed in 14th-century Japan. Instead of broadleaf trees, it uses Kitayama cedar, or sugi, a relative of the giant sequoias of California. And instead of cutting down a tree to make a stump, daisugi relies on careful pruning using techniques similar to bonsai.

“Dai” means table in Japanese, so daisugi means table cedar. It leaves enough lower boughs on the tree that it looks like a table with thinner trunks growing from it. When someone plants sugi that will grow the ordinary way, neither he nor his children will harvest it. It won’t be ready until the grandchildren’s generation. Daisugi, on the other hand, become ready for harvest after 20 years.

All but the top boughs are pruned away periodically. That enables a perfectly straight trunk. When harvested, it has no knots.

Samurai culture developed a style of architecture for which the cedars provide the only suitable wood. There were not enough of the trees to supply the demand for it. With daisugi, all the samurai who wanted houses made with straight knot-free sugi could have one. At the same time, the same style of architecture served for tea houses. Meanwhile, the trees that provided all that wood could live for hundreds of years.

At the same time, daisugi wood is stronger, denser, and more flexible than that from ordinary sugi trees.

Coppicing, pollarding, and daisugi are not currently used in commercial-scale forestry. There seems to be no reason why these neglected techniques could not be scaled up. Advantages would include better land management, wood becoming ready for harvest sooner, enhanced biodiversity, and more.