SciSun: Downtown Abies   Leave a comment

On a hot summer day, waking under the shade from a sidewalk tree is a great way to avoid the blazing sun. Or finding shelter under one of these urban trees can protect you from a sudden cloudburst. And parking your car next to a tree in the mall parking lot means it should be a lot easier to find your car later – if all the trees in the mall parking lot didn’t look exactly the same. Because the trees most of us see every day, while nice and green and natural – often really aren’t the trees we should see every day. The usual urban tree – the trees planted along sidewalks, and on street dividers, and in parking lots is more than likely a species selected because of it’s shape and availability and same-ness to all other similar trees. No big deal, you might think, it’s just a decorative tree and hey, it’s keeping me (or my car) out of the sun.

This might be true, but if cites and neighborhoods and malls are going to plant trees, why not make them the same types of tree that would naturally be found in the area? Throughout the early decades of settlement and growth in North America, much of the native forest, woodlands and wild places were cut down and leveled for construction and development. It’s much easier to build when there aren’t any of those inconvenient trees in the way! Then, in the 20th Century, people starting noticing something was missing in their cites and neighborhoods and along roadsides – something like trees! (Also missing were the streams and meadows and birds and animals that lived among the native trees that were gone, but no one thought much about that). So massive tree-planting began as way to ‘beautify’ urban environments. Trees like Dutch Elm (Ulmus americana); various Maple (Acer sp.); Eastern Red Cedar (Juniperus virginiana); Flowering Pear (Pyrus calleryana); and White and Balsam Fur (Abies balsamea and Abies concolor) were planted in the millions. Spaces dominated by these very limited types of species created monoculture environments – areas where there are so many of one type species, there’s not enough diversity to allow for a healthy ecosystem. But, all these identical types of trees lining the streets are pretty to look at!

Which one of these is not like the other?  A boring, utilitarian monoculture.

Which one of these is not like the other? A boring, utilitarian monoculture.

Unfortunately, these monoculture designs can lead to disease or parasites or even species-specific types of insects or animals that could virtually wipe out entire regions of plants in a short time. Over just the last sixty years, millions of Dutch Elm trees have died due to Dutch elm disease; Fungus and Wilt is destroying the leaves of Oak trees; and worms and beetles are eating the bark from Pine and Furs. In a balanced ecology what effects a few trees would remain in a small area; but when one tree (or any plant or animal, for that matter) is so close to countless others of the same species, it’s too easy for disease and insects to move right next door and continue to spread.

What can be done to protect our urban ‘sidewalk’ trees, and create a more healthy and enjoyable environment for everyone? (everyone except those insects and diseases and fungus that are killing the trees. They’re real downers). Obviously, don’t plant all the same types of the same plants! Many cites are replacing and re-planting monoculture spaces with mixed polyculture species that create a more healthy habitat and enjoyable, varied background to our usual urban spaces. (Although some planners and neighborhood associations still plant many of the same types of trees because they ‘look pretty’ and are easy to care for). And it’s important to try and plant the trees, shrubs and flowers native to our local environments – Maple trees may have brilliant autumn colors, but do they really belong in a Southwest desert city? We know non-native species can actually cause harm when they’re artificially introduced into an area; plus, native species will attract birds and bees and other wildlife.

This messy-looking jumble of plants is actually a healthy polyculture

This messy-looking jumble of plants is actually a healthy polyculture

So if it’s Downtown; Uptown; Midtown; or Around Town, no town would be much of a town at all, without trees.

http://www.urbantreekey.org/

http://www.dnr.state.md.us/forests/publications/urban.html

^^^

Michonne Says: Trees are great! I like to sit under them or dig under them or smell their flowers or watch them move in the wind. And they make piney-cones that are good to chew.

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