One of the first things I do when assessing a tree’s health is look down. So much of what we as arborists as problems in a tree’s canopy originate from issues underground. Soil compaction, buried root flares, lack of soil nutrients, and improperly planted trees are some of the most common tree health concerns I see on a daily basis.
So what can be done to remedy these problems? Well, prepare to meet what might be my favorite tool in our industry: the Air Spade. As opposed to manual digging tools, an Air Spade allows us to control highly compressed air to move soil from a tree’s root system with very minimal, if any, damage. It should be noted that any disruption to the soil around a tree inevitably damages the soil’s microbiome. It is up to a trained arborist to determine if and when using the air spade is the right call. We use this tool for numerous tasks, some of which we’ll go over in this article.
Root Collar Excavation
You may remember an earlier article entitled “Root Flare: Where Trees Meet the Earth”. In that article, we discussed the importance of a tree’s root flair. It’s extremely common in an urban environment for a tree to be planted too deep or for mulch to be built up to an excessive level, burying a tree’s root flare. Over time, this can lead to stem-girdling roots that can encircle a tree’s stem—or trunk—and prevent the uptake of nutrients.
It can also lead to root decay, which can eventually lead to tree failure. Using an Air Spade to expose a tree’s root flare is perhaps the most common application for the tool. An arborist is then able to prune any roots that may be growing in a way that is detrimental to the tree’s health.
Vertical Mulching and Radial Trenching
When a tree is looking less than great, another common cause is soil compaction. Over time, constant foot or vehicle traffic, as well as construction, can compress the soil around a tree preventing the uptake of oxygen, water, and nutrients by the tree’s roots. We use the Air Spade to decompact the soil in two ways.
Vertical Mulching is much like aerating your grass. We drive the tool straight down into the soil, creating a vertical tube. This is repeated in a grid pattern around the prescribed root zone. Finally, we backfill these holes with compost to boost the nutrients in the soil. The second method is called radial trenching. In this procedure, the air spade is used to create long trenches that fan out from the root flare of the tree, and are then backfilled with compost. Both methods are designed to cover as much surface area as possible while still retaining the soil’s preexisting microbiome. Our arborists are able to make an informed decision as to which method should be used.
Occasionally, trees end up in the wrong location. Whether it be due to construction, the size of the tree, or simply to make way for something else. As an alternative to removing a tree entirely, an Air Spade can be used to help us move a tree from one spot to another. By exposing a tree’s root’s we are able to make safe pruning cuts to extract the tree and replant in a different location. While this can be a risky procedure, it can be worth the effort!
Oftentimes when we see trees that are in decline, they are suspiciously close to some form of new development. This may be a new driveway, an addition to a house, etc. While the issue may be just compaction from the constant presence of construction machinery, compiled on construction backfill devoid of nutrients, many times there is root damage present as well. An air spade allows us to expose and preventively prune roots back from a construction project so that they aren’t destroyed by machinery.
Truetimber wants to see Richmond’s trees thrive. If you have a tree that looks like it could use some love, have us take a look. We might be able to discover the ‘root’ of the problem.