I have a white popular (Populus alba). We will be in the process of creating a new enterance to our compus. The architect calls for protecting the tree. It is about a 36" DBH, I guess and about 50 foot tall. It was topped perhaps 10 years ago, so it would need corrective pruning eventually. The tree sits on the corner of a gravel parking lot that created 2 years ago. The area will be diverted to landscape and grass. A sidewalk is in the plans. This would come close (about 4 ft of the tree). The tree appears to be healthy with the exception of needing the corrective pruning. Could one place the protective barrier as 1"=1' radius from the trunk or would the drip line be the rule of thumb? Any suggestions?

Reply to post by Gerald, on March 13, 2000 at 12:30:23:

Hi, Gerald. Sounds like an interesting project.

The radius for the protection area should be based on several factors. The dripline is imaginary, and only represents a very rough estimation of the root zone. Your suggestion of 1":1' seems a better option, if you can get that much room. You may need other adjustments if there have been past disturbances (the parking lot) or obstructions to the root system. Obviously, the larger the protected area, the better for the tree.

One option for the sidewalk is to convince the architect to investigate a "bridge & pier" system that spans over the root zone without requiring disturbance of the soil. Piers are set as needed between the major roots, and prestressed slabs supported on the piers. A light gravel base can be placed underneath and alongside, if needed. This is to avoid any cutting or compaction of the soil to prepare a base for the sidewalk.

Reply to post by Gerald, on March 13, 2000 at 12:30:23:

It's deja vu all over again: We have a short-lived tree that has many distinctly undesirable traits. We've beat-up on it for decades... we topped it and we put a parking lot under it. NOW an architect has latched onto it, declared it significant, and no expense shall be spared in preserving it.
Perhaps poplar is all you can grow in your location, but Dirr says: "if anyone plants poplars they deserve the disasters that automatically ensue...avoid this pest." Amen.

Reply to post by Gerald, on March 13, 2000 at 12:30:23:

I agree with Ed (and of course with Russ)but be careful cutting poplar roots. They sprout vigorously in response to cutting and if you are not careful you will end up with a host of suckers all over the place. If you must cut the roots install a deep root barrier and buy some time that way. P alba is a vigorous sprouter and likely to be a problem anyway, so maybe a replacement (right tree in right place) may be a better option.

JD

Reply to post by Gerald, on March 13, 2000 at 12:30:23:

Some good points here. I will give this consideration. The project has been put on hold for this year because of right of way access problems up the street. This will give me some time to educate and find better options. Here in Montana, tree protection is primitive and hard to change attitudes. The architect calls for tree protection which is not explained at all. I wanted to have my research available to bring ideas to the table. I too am not all that impressed with the white popular or with most populus species unless placed in low maintenance places. While our plant selection may not be as extensive as the eastern and southern areas, I am able to select from a variety of cold hardy, alkali tolerant, and urban tolerant plants. Thnks for your opinions. Gerald