When talking with people about trees in their yards, one of the questions that I often get asked concerns adding, or removing, dirt right around trees or in their root zones.
For instance, I remember years ago, when I was talking with a client about a red oak that was said to have been planted in 1898. While this particular tree was in a residential, private property setting, the community it was in was aware of and fond of it. Anyway, while we were discussing the tree, as an aside the homeowner mentioned that he was planning on adding three feet of new soil to the area around the tree.
I was glad he mentioned that, as it almost would certainly caused the death of that tree, and I told the client so.
Alas, while I might have saved that tree from a slow suffocating death that day, that particular homeowner came up with a different method of seriously damaging that tree, to the point that it looks horrible, and I don’t see recovery in its future.
Getting back to adding or removing soil around trees. To set the stage, what a tree does, whether started by nature, or planted by a property owner, is to establish where it finds itself, and put its roots in the most optimum part of the soil area that it can find. For the purposes of this discussion, that means that a tree is going to place its roots at the depth that gives it the best results.
Just to be clear, some planting sites are not that great, and when I say “best results,” often that just means it’s doing the best it can in a not that great planting area. However, a tree naturally is going to do the best it can, and the depth of the root system in a particular soil area is important to a tree, and not something that a tree can adjust if conditions at the site are changed around it. Also, I certainly could make the case that the less suitable for trees the growing area is, the more sensitive to any changes a tree growing in it will be.
Keep in mind that West Texas (meaning our region), is not generally a tree friendly place.
While trees are very adaptive and evolution has equipped them with all kinds of ways to deal with the things that naturally happen to them, apparently changes in soil depth are not something that happens often enough in natural settings for trees to be equipped with a way to deal with it.
Granted, there are a few exceptions, such as bald cypress trees, although with them, it has more to do with growing in water, or in places where water sometimes brings in sediment to stack up around them. Still, even for a bald cypress, changes in soil depth, whether deeper or shallower, are detrimental.
One thing that I have noticed about giving advice to people to not add or subtract soil around trees is that a lot of people don’t take it seriously. After all, trees live in dirt, and get all of their nourishment there, what could possibly hurt about moving some in, or out, around it? When I talk to other arborists about this, they all say pretty much the same thing about what a serious issue it is, but how hard it is to convince people of that.
Personally, I have seen lots of trees killed, or really damaged this way, but since it takes a long time, sometimes many years, for the damage to show up, it can be hard to convince people that dirt work done several years ago is the actual problem.
A few words to the wise about planting trees – Abilene Reporter-News
