Treatment advice for 4-5' DBH Doug-fir growing against concrete, 25% circum., please.

[SeanKroll]

Been doing a bunch of Root Crown Excavation and Stem-Girdling Root pruning lately.

This dropped into my lap today. Property owner type of guy with waterfront, fancy car. This looks like a meeting facility, residence. I was looking at pruning some low walnut limbs at this place and saw the doug-fir. I was at another of his properties for building clearance pruning and saw this beech (?) cabled and chained.



All starting by being at his neighbors' house and seeing a fading property line triple-trunk fir.




This tree is one of the large ones left near the Capitol. https://www.google.com/maps/place/1...8b26bf80f027a!8m2!3d47.0338647!4d-122.9046289


Seems like the basic part is to cut the concrete away from the collar enough for growth (start farther away from root collar), then work my way back close to the trunk. This will give me access to the enveloped concrete. Seems like I would need to try to bore horizontally with the concrete saw, if possible. Then 'carefully' chisel out pieces. How do you chisel concrete carefully when enveloped by compressed bark and wood? Once, when I cut a 2x4 deck board that was grown against by a western redcedar the bark kept expanding and closing the kerf. I imagine that this will be the case here, too. Easier to keep reaming the cut in wood. The cedar pushed out about 1/2".

After that, there is the question of how to care for the compacted tissues, and what to back-fill with (something very porous)?

 

[Burnham]

I have never done anything like this, Sean. So my ideas are worth not much. But I'd just chisel out the concrete sections along the mortar line outside the over growth zone by drilling through the mortar every few inches, then smack the shit out of the sections between the mortar and the tree with a sledge hammer, and pry them out with a 6 foot fencing tool. Don't worry about hurting the tree, it'll callus over the wounds you cause. It's a Doug, fer heck's sake...it'll take it . Backfill with normal local soil.

Hard work, but it'll be OK, I think.

Or adopt another attitude...have you never seen a big old Doug that is growing out of a rockpile of a site, out in the woods? Growing over and around native rock structures not a bit different than your city tree, probably worse, to be real about it. I sure have, many a time. They do fine, almost always...and for many hundreds of years. I might well just leave that tree alone. It really doesn't need fixing, in my opinion.

 

[Mick!]

Agreed Burnham (second paragraph anyway)

 

[flushcut]

What B said.

 

[SeanKroll]

All faux finish lines in poured concrete, driveway-thick/ couple inches. Not stone and mortar. No weak joints to break.

What looks like a slab of rock against the tree is just where a small piece of the concrete wall was broken free by the pressure, presumably, and pushed out 3", over years of growth.

How much do you figure a tree can grow against a boulder or bed rock without significant effect?

I have never seen big Doug-fir growing against big rocks, particularly. Probably more exposed rocks at higher elevations. I'm sure you've seen it. No doubt.

I've seen lots of effect where to trunks crush each other to death at an inclusion. Inclusion of a two-trunk tree will never affect more than about 20-25% circumference, I'd bet.

I've seen significant trunk dieback and death of trunks in multiple- stem maples (easy example).

Old growth trees rarely stand out alone, rather, they are in forests. These big trees around the Capitol are all very wind-exposed at the top of a hill with prevailing wind coming up the hill, probably, Fwiw. If roots are being compromised, it's the windward roots, for prevailing winds. Often it's the opposite to prevailing winds that topple trees, since trees compensate to their loading.

 

[Burnham]

As to the faux finish...just drill more holes closer together...it'll break off no problem.

I still would leave it alone.