Whether it’s a removal or pruning estimate or a hazard assessment, the first and foremost thing I look at is the area where the tree goes to ground. Why is this so important?
You wouldn’t put a new roof on a house if the foundation was shot, would you? I am often asked what the roots on a particular tree look like, where they are, how deep they grow, etc. Frankly, no one can say with any certainty! Without ground penetrating radar (doesn’t work on all trees and all soil types), or pulling the tree out of the ground and shaking all the soil off, we have to make an educated guess.
My first “red flag” is a tree trunk that plunges into the ground with no flare or increase in diameter. The root buttress, or root collar is a portion of the tree that NEEDS to be above the soil line. Any tree that has no visible root collar or flare has either been planted too deep, or has been buried due to a raising of the grade.
The same goes for mulch. if you have mulched your tree with a nice layer of coarse to medium wood chips starting about 1-2 feet away from the root collar and extending out to at least 1 1/2 times drip line, good for you! The tree and I thank you, just be sure the mulch doesn’t “migrate” up against the tree.
Soil-born pathogens are very patient. They just sit there and wait to be piled up against the corky part of the tree’s bark, add a little moisture in the summer time, and they are off and running!
If the tree is small enough it may be dug up and planted properly. If the tree is too large for digging, a root collar excavation must be performed. This is a delicate operation as is and it is extremely easy to damage the tree’s root collar by roughly removing the offending soil. How deep should you go? Until you expose a (hopefully) well formed root collar. My record is 11 feet!
After the excavation, you must insure that organic debris can’t accumulate in the “well.” When planting a new tree, use caution when digging the planting hole. Plant just a tad, to a tad and a half higher than you think you should. Things will settle as you water the new tree.
Wild trees are almost never “planted” too deep. Take a walk in the surrounding hills and dale around town and look at all the beautiful root collars. Excellent!