Re: pits and planters
llesser@laughing.earth
Sat, 17 Aug 1996 16:37:52 -0500
I STRONGLY recommend that you read James Urban's work on urban tree planting pit design (check Landscape Architecture - April 1996, I believe). One point he brings up is that mature trees generally need at least 600 cubic feet of soil (1200-1800 c.f. is much better) with good air and water percolation, with a depth of about 2 feet. His work is supported by much research elsewhere. Try also Nina Bassuk's work on load-bearing soils under sidewalks (Journal of Arboriculture, within the last year). Her research focuses on creating a soil environment under sidewalks that allows tree roots, air, and water to penetrate (making all of that formerly unavailable soil volume accessible to trees), while providing sufficient support for sidewalks and reducing (hopefully) the incidence of sidewalk/root conflicts.
It also sounds as if you're headed in the right direction with shared soil volumes. Be warned, though: too many landscape architects are totally (and I do mean completely) unaware of a tree's basic needs. Do the research, design the planting environment, try something a little different, and we'll all be a lot better off for it. Let me know how things work out! I can be reached by slo-mail (not e-mail, unfortunately):
The Laughing Earth
2239 Bonita Avenue
La Verne, CA 91750
Good luck, and keep in touch! --Lawrance Lesser