Help With Root Prunning

[bigtreeguy]

Can anybody help me determine the safe distance from a mature Locust Tree that roots can be pruned? This is a neighbor dispute regarding a 32' DBH Honeylocust Tree in a back yard. There is a house as a potential target, so, stability is an issue. The roots in question are on the west side of the tree with northwest prevailing winds.

 

[John Paul Sanborn]

One school of thought is the "Critical Root Zone" or CRZ. This was developed because the dripline concept does not work for narrow crown form trees (columnar, fastigiate...).

CRZ is a 1 ft for every 1 in of DBH

I could not find anything on it in a quick search right now though.

The CRZ model is for trenching and excavation where an otherwise indescriminant line would be drawn.

If you want to sever a few major roots 12 ft out, you do not have much to worry about. Your biggest worry is root rot, and Gleditsia compartmentalizes well.

 

[treeseer]

Depends on many factors--tree vitality, root architecture, soil type, length and depth of cut...you and your neighbor need an experienced arborist on site.

 

[bigtreeguy]

I am an experienced ISA Certified Arborist. This is a dispute between a customer of mine and his neighbor. I would like to be able to site a source when I make my recommendation. I need to find some published standards.

 

[John Paul Sanborn]

Here is a search that rendered some hits.

http://www.dogpile.com/info.dogpl/s...-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/417/top/-/-/-/0

 

[treeseer]

CRZ does not answer the specific question, though. Coder has said no cutting within 6 feet, Stewart in his Building WITH Trees said...I'd have to look at my notes. Are you an advocate for your client in this case or an independent consultant?

One source is page 171 of Trees & Development by Matheny and Clark, and Chapter 6. Easy to buy, read and cite.

Another source is Cullen's protocol in the Landscape Below Ground Proceedings.
Easy to buy, read and cite. There are others too. :help:

If you're making recommendations you need familiarity with these sources. I'd do you little good and possible harm by sending you snippets.
:greenchainsaw:

 

[bigtreeguy]

I am an advocate for my client and will present my original recommendation for no excavation. I appreciate the helpful response from both John Paul and Treeseer and will read your suggestions for future reference. Thanks, Mark

 

[John Paul Sanborn]

Here is a PDF with a CRZ formula used by GA.

http://www.gfc.state.ga.us/Resources/Publications/CommunityForests/CommunityTreePlanting.pdf

 

[Tree Wizard]

Why don't you hire someone with a TreeRadar unit and do a bunch of root scans. Then you'd have a good idea where the roots are and the impact excavation would have.

 

[treeseer]

Good link, JPS. Bottom line seems to be that trees can routinely sustain root loss <30%. An objective consultant would have to mention that, but an advocate could leave that fact out and instead focus on fuzzier formulae such as 1.5x dbh = CRZ.

I seldom take the advocate role, because you don't have to tell the whole truth. Too much like lawyering.:blob5:

 

[John Paul Sanborn]

focus on fuzzier formulae such as 1.5x dbh = CRZ.

I think if one focuses on the range, with 1.5ft:1in being the lower limit as an industry acsepted Rule Of Thumb it would not be as fuzzy. Having caveats with species dependancy and long term maintainance needs would help further.

My understanding is that CRZ was developed studying a broad array of trenching projects on mature trees.

 

[treeseer]

1.5ft:1in being the lower limit as an industry acsepted Rule Of Thumb it would not be as fuzzy.

I agree that rule of thumb is useful and good, but it is by nature fuzzy, as is the recommendation for no excavation. The key is: What is Reasonable?

Without looking closely at all the variables in the tree, no reasonable recommendation can be made. All statements are posturing and staking out negotiating positions without a good inspection. Drawing lines in the dirt and negotiating may reach the right outcome for the tree, IF both parties are reasonable.

In my experience this seldom happens without objective information specific to the tree being agreed upon.

 

[Ekka]

Bigtreeguy

May I ask why the cutting is neccessary?

Would tunneling or vacuuming be an option leaving roots intact?

I've also read somewhere that as long as the cut roots are under 1" dia that they're not structural support.

But I'm trying to understand that if 2 neighbours are discussing where to prune the roots there must be a reason for it, the other influencing factor is the closer to the tree the better for who-ever wants these cut.

 

[bigtreeguy]

Ekka,
No, tunneling or vacuuming would not be an option. The reason the root pruning became an issue is because my clients neighbor believes the cracks in his garage floor are caused by the roots from my clients tree. I do not believe they are, but my client would like to appease his neighbor if it could be done without hurting his tree. I do not believe it is worth the risk and have advised my client as such. This is a big beautiful Locust Tree that shades the house and back yard all afternoon. I have pruned and cared for this tree many times in the last 15 years, so I am sure my decision is presented with some bias.

 

[treeseer]

Why not just get out a shovel and dig along the edge of the garage? If a root is found growing toward the crack then consider pruning that one root.

 

[Ekka]

Why not just get out a shovel and dig along the edge of the garage? If a root is found growing toward the crack then consider pruning that one root.

Maybe subsidence, removal of soil moisture at even a further distance has an effect. Full docs at TW.

 

[bigtreeguy]

I did that. Not a problem near the crack and the foundation it not damaged either. Like I said, I don't think the tree is causing the problem.

 

[treevet]

Around here quite often foundation repair companies will not guarantee work unless tree issues they perceive, valid or not, are addressed and corrected. Also often it is not roots pushing against the foundation but rather dry weather causing a gap btwn the soil and the foundation allowing movement and causing cracks. Trees may be thought to contribute to that lack of moisture. It is prudent to "water your house" sometimes to eliminate that gap.