About Your Tree’s Roots
The ground is a lot like the ocean… there is abundant life below the surface. Trees participate in that underground ecosystem. Their roots do a lot more than just hold the trunk upright… They store energy over the winter and collect water, minerals, and nutrients. They also interact with a host of bacteria and fungi some of which are synergistic and others not so much.
So what does all this matter to us above the ground? Although we can’t see or always understand what is going on “down there” we do have an effect on it. In healthy forests there is thriving soil life built up through years of biological activity. In our back yards there is a lot less of this, and though trees are tough and often do well in-spite of that, they can only take so much…
Compaction from things we do around our yards can squish the air out of soil killing a lot of the bio-diverse life in it. Over fertilization (think nitrogen on your lawn) can cause imbalances and kill fine roots. Grass and other plants can compete for water and food, preventing the tree roots farther down from getting enough.
There are a few simple things that we can do to help with most of these problems. A single big one is mulch! 2-3 inches of organic (Just meaning from living organisms, not necessarily “certified organic” as it often means now…) biodegradable mulch spread to the “drip line” keeps grass away from the roots (you won’t be mowing there) so it reduces compaction, retains moisture, and as it decays, builds soil.
There is a list of don’t do’s:
- Don’t raise the grade (3-6 inches of ground added on top of existing can be enough to kill roots).
- Don’t pile dirt against the stem (root flare should be visible)
- Don’t cut the roots (with trenches or going too deep with a lawn edger etc.)
- Normal use is pretty harmless, but parking cars under a tree regularly or having a lot of people walking under it can eventually compact the soil enough to hurt the tree.
Often something we are doing makes root damage unavoidable, but being aware of it we can usually adapt our plans a bit to improve the situation. Remember that roots often extend much farther than the trees canopy, often spreading twice as far as the branches. Also, cutting a large root close to a trees stem can easily be removing 1/4 or more of its usable root system.
This is just a touch on the topic of tree roots, here are a couple of links to articles that I’ve found interesting: https://extension.colostate.edu/topic-areas/yard-garden/healthy-roots-and-healthy-trees-2-926