Why Suburbs Will Never Have Tall Trees

Continuing our focus on trees here at the Rant, check out this article about suburban trees in July's Landscape Architecture Magazine.  That link won't show you the whole story, so here's what it says about the ways that tree growth is stymied (and tree death promoted) in new developments:

• Heavy earth-moving machines create oxygen-deprived hardpan around new homes.
• All but a few inches of topsoil are removed and sold off, leaving just enough for sod.
• What topsoil there is often contains debris-filled "builder's loam."
• Holes are bored into the hardpan to plant saplings, causing roots to circle the planting hole and the trees to eventually decline.

And as I've noticed in my own neighborhood, the hardpan hasn't improved a whit in the 80 years since the earth-movers did their damage - at least in spots where no organic matter has been added.

This reminds me of the time the sidewalks were replaced on my own street.  We learned from talking to the city that the contract for the work required 4 inches of topsoil in the hell strip between the street and the sidewalk, but what we actually got was about a quarter inch - just enough to fool the eye.  Underneath was pure builder's loam - concrete rubble, rock, and little else.  That is, unless the homeowners stood guard during the work to force compliance with the contract specs.

Which makes me wonder what, if any, topsoil requirements exist for new housing developments and if there's any enforcement if they do exist.  Because hey, what developer can resist the big money to be made in stealing topsoil from their buyers?

Photo:  You've seen it before but doesn't it nicely illustrate what you can grow - even in a hellstrip - with actual topsoil? 

Comments

[JLB]

There's another way tree growth is stymied (at least, this was the case at my house in Washington): construction workers dumping excess concrete used to pour the foundation just a few feet from the home. You'll be happily digging along one day with your master plans for planting trees, until you hit concrete just 1-1/2 feet down.

I sure like your idea about regulations to enforce the preservation of topsoil, but I have a hard time imagining that developers would ever respect it. More likely they'd strip the topsoil, and then truck in more from somewhere else - just to inflate their profits.

[Trey]

There is another reason that trees in new neighborhoods will never be tall. The varieties being planted are in many cases dwarf or smaller growing types. The trend as we have seen is for low-maintenance yards by our overworked suburban dwellers. One way to reduce the maintenance is planting smaller or narrower growing varieties. “I don’t want to have to clean up leaves”, “I don’t want it ripping up our sidewalk, or “I didn’t know trees reduced energy consumption in the home”. Take you choice. That’s what they are saying. So they plant smaller growing trees. Remember http://thegoldengecko.blogspot.com/2006/09/tree-can-save-us-money.html this post where I mention a study that showed that 70% of respondents did not know landscaping can cut energy costs. So you have lack of information coupled with the desire to do as little as possible in the yard and you have the shrinking tree canopy.

Sacramento is known as the “Tree City”, yet who now would plant giant elm, sycamore, or other large trees? These trees while providing wonderful shade lift the sidewalk, leave incredible amount of leaves, and blow over onto homes. So the new subdivisions are filled with Crape myrtle, flowering plums, and other lower growing trees.

Disturbing the soil during construction also disturbs the naturally occurring http://www.mycorrhiza.com/index.php?cid=386 mycorrhiza that exists. Studies have shown that this important beneficial fungus helps plants to grow better. When the soil is disturbed the mycorrhiza is destroyed. So not only is the soil compacted it’s minus this important beneficial fungus. You can add this fungus to the soil before planting or after but it is so new most people don't know about it.

[Carol]

Do developers really take the time to sell off the top soil, or is it all just buried under as they excavate for sewers, water lines, roads, etc.?

[Pam/Digging]

That doesn't seem to be happening here in Austin. Most new houses I've seen have a mandatory sapling live oak in the front yard. That's about as big a tree as you can grow here, though of course it'll take 50 years.

[Pam]

I think the developers do take the time to sell off the topsoil, at least here in the southeast. They make decent money here (as an 'extra') - but we also have all of these new neighborhoods with trees barely making it. As someone who took alot of soil science in school, my feeling has always been that good soil is just something people take for grant - soil is soil - but those of us who 'work in it' know that not all soils are like, heck, not all "soils" are even soil! I was telling someone recently that I looked at a soil map of where I live before buying my place, and they said 'A what? Why?' Most people just don't know. With oil prices being in the forefront...do people 'get it' that soil is probably one of our most important non-renewable resources? (Non-renewable in a true soils sense with respect to geological time).

[Beth]

I see it all-too-often. Construction debris left to be buried in the soil. No concern about existing trees when the the poeple who bought the lot to build a home on, bought the lot because it had a lot of trees. As a county horticulture agent, I see and diagnose many dead trees due to construction damage. It's a dang shame....