[CANUFNET] Constructing Driveways within Critical Root Zones

[Michael Richardson]

It all sounds good putting geotextiles, aggregates, and a surface down but
there are issues to think about.  As we all know decline can take years to
appear as stored carbohydrates are slowly used.

1) weight alone can cause compaction, vibration of machinery can cause
compaction even with low bearing machinery
2) without a highly permeable surface you reduce influx of water and may
create a dry zone
3) the materials used will intercept water and cause longer and more
intense drought situations as smaller rainfalls will not penetrate as they
are adhered to more particles before they reach the soil (gravitational
water path is lengthened)
3) oxygen and carbon dioxide movement will be affected
4) diffusion path will be lengthened and flux~1/d*d, thus small additions
of material will cause greatly decrease flux
5) carbon dioxide accumulates lower in the soil profile and is flushed out
by rain, thus carbon dioxide will build in the soil
6) parking over tree roots can add salt and hydrocarbons to the soil
7) the driveway to will largely eliminate organic matter input into the soil
8) permeable surfaces can become clogged with grit etc., over time.


> Hello Canufnet members,
>
> I have a client that is building two homes on an infill lot where there is
> a very large (106 cm), healthy silver maple. He is very willing to
> explore different options for working around the tree that would cause
> minimum disruption to the roots.
>
> Does anyone have examples of building driveways within the critical root
> zones of large trees that have managed to prevent significant root damage
> and tree decline? Specifically, he is considering a type of elevated
> driveway that would not require the severing of roots or significant soil
> compaction, and dissipate the pressure through posts. Although the posts
> would cause some root damage, it would be significantly less than
> excavation for a standard driveway. If anyone has examples of this type of
> engineering, I would be grateful if you could share it with me.
>
> Thank you,
>
> Astrid
>
> ______________________________________
> *Astrid Nielsen, *MFC
> Ontario Registered Professional Forester
> ISA Certified Arborist®
> ISA Tree Risk Assessment Qualified
>
> astrid.nielsen at dendronforestry.ca
> +1.613.805.WOOD (9663)
>
> www.dendronforestry <http://www.dendronforestry.ca>
>