Why does deep planting encourage girdling roots?

[lumberjackson]

My understanding, with no data or scientific method to back it up, to why deep planted trees are more prone to circling and girdling roots is that 1) they were planted too deep, so the person planting it never saw and corrected the problematic roots that came from the nursery and 2) the soil around the trunk promotes adventitious roots that don't have the necessary hormones and receptors to grow radially. I think the adventitious roots we're discussing tend to be geared towards water uptake and gas exchange to offset the challenges that come with being planted too deep, rather than structural support. So, when those latent buds decide what they want to be when they grow up, they don't activate the genes for buttress roots, rather they activate the genes that will alleviate the immediate stress from the soil against the trunk the most efficiently.

Again, I'm not the biology degree you're going will chime in, nor do I have any empirical evidence, but my theory makes sense to me!

 

[Basswood]

My guess...the tree already has a root system. It cannot support both.

On cuttings, do they develop a true root flare...they do, right? I think of the true American elm DED-resistant cultivars. It is my understanding those are all propagated with rooted cuttings because if they used non-resistant root stock, the tree would still get DED. They have trunk flares. So, at some point, the tree "decides" this is my trunk flare. I have never seen that on a secondary root system except on a couple of American hornbeam trees.

View attachment 85043

You can see here, it looks like the secondary roots were "behaving". I still planted it at depth of the original root flare.

I’ve always wanted to test these situations by eliminating the original root flare and keeping the secondary. Kind of like air layering/ground layering.

Curious as to how sustainable leaving a tree like that is long term.

 

[southsoundtree]

I wonder if there is a very small space that develops between the trunk/ roots during the dry/ growing season as soil dries and shrinks that allows more air into that space where roots can grow around the trunk forming circling roots.

 

[evo]

I wonder if there is a very small space that develops between the trunk/ roots during the dry/ growing season as soil dries and shrinks that allows more air into that space where roots can grow around the trunk forming circling roots.

interesting thought. I see this all the time after wind events on trees without flairs exposed. Micro stem movements.

 

[Alec]

Just circling back to this oldie-but-goodie thread to say y'all are amazing. Such thoughtful stuff.

I wonder if there is a very small space that develops between the trunk/ roots during the dry/ growing season as soil dries and shrinks that allows more air into that space where roots can grow around the trunk forming circling roots.

Super-interesting proposition!

 

[Alec]

Just circling back to this oldie-but-goodie thread to say y'all are amazing. Such thoughtful stuff.