Turn, turn, turn

Consider the lowly stump. 

This mundane and ubiquitous object is familiar to everyone, but hardly ever warrants a passing thought. If one does stop to consider a stump, it is usually in lament for the tree that is not standing there any more. Let’s look a bit closer and think about what a stump represents. 

First and foremost, a stump is indeed a reminder of the tree that once grew on that mighty pedestal, but, in reality, a stump is half of a tree. Both in volume and in area, the stump and connected root system is the equal counterpart to the above ground half of a tree. Fully half of the biomass and carbon present in a forest exists below ground. The stump and its spreading mass of roots, root hairs and mycorrhizae make up a massive underground ecosystem. And in area, the root system is equal to the above ground tree as well. As a general rule, the horizontal area of a tree’s crown is equal to the spread of the below ground root system. Just as the branches of individual trees touch in the canopy, so too do the roots of trees communicate with each other below ground. Thus it is important to think of a stump, not merely as a small remnant left after a tree is cut, but as the above ground indicator of the other half of the tree that has remained in the forest. 

And it remains for a long time. Under normal circumstances, the stump and root will take the same amount of time to fully decompose as it took to grow the tree in the first place. As the root decomposes, it sends nutrients to its neighbors, and it builds carbon in the soil, continuing to serve a beneficial function in the forest ecosystem. The average age of an oak tree cut in the Zena Forest is 120 years. That tree started growing in 1900, and the root will continue to build soil, sequester carbon and support its neighbors for another 120 years until the year 2140. From this, you start to see the value of longer harvest cycles - each year the tree gives two years of carbon sequestration. And not only do older forests store more carbon, but bigger older trees produce higher quality, longer lasting wood products. But that will have to be the subject of another blog post.

Now consider the tree that grew on top of the stump. Some parts of the tree will change state fairly quickly. The leaves and branches will start decaying on the forest floor and disappear within a decade or two. The trunk will go to the mill to be sawn. The sawdust will be used to grow mushrooms, and then as fertilizer.

The boards, however, will be used to make flooring and furniture which will last on average another 120 years, sequestering carbon and providing functional benefits for a family not far from where the stump and root is still playing its role in the forest ecosystem.

There is a wonderful symmetry to this process that is much more complex than the binary concept of tree and stump. As you are reading this, look down at your floor, or your table, or chair, and consider the stump from whence that wood originated. It still exists, and is serving a very valuable purpose somewhere in a forest.

There is a symmetry and balance inherent in a forest ecosystem, just as there is in the wood products that we derive from those trees.