Updated ranch with in- law possibilities
The condition of the urban forest goes beyond pure aesthetics. A leafy city is a cooler, cleaner city; it's simply a nicer place to live, and it makes us healthier in mind and body. The tree, it turns out, is the one hugging us.
Today, the nation's capital has an active program of replacing dead trees and uses interactive maps to encourage residents to get involved in the care of newly planted trees. Moreover, there is a collective sense that in an age of climate change and more extreme weather, the need for a healthy urban forest has never been greater.
There is another aspect of this revival that I find compelling. Today, we have a mix of street tree species and varieties that seemed unimaginable just a few years ago. This eclecticism is not some passing fancy but reflects a fundamental shift in what constitutes a suitable city tree in the 21st century. This change was led in part by the late Frank Santamour, a research geneticist at the U. S. National Arboretum who invented a formula for urban forest biodiversity.
Washington is a leader in this tree diversification movement, but it is not alone. "The same concept is going on all around the country," said Keith Warren, a prominent tree breeder, nurseryman and author. "It's a cumulative awareness of the dangers of too narrow a selection of genetics in the urban forest."
Washington's urban forest - which years ago saw an alarming decline in the canopy of the urban forest due to neglect and development - is lush and vital. I am finding trees along city streets that I had previously thought of as choice ornamental plants. These include the serviceberry, sweetbay and cucumber magnolias, Japanese apricot, American hornbeam, Persian parrotia and red buckeye. A few weeks ago, I was stopped in my tracks by a deciduous yellow blooming magnolia hybrid named Butterflies that previously might have had gardeners salivating at a rare plant sale.
One obvious reason for the contemporary assortment of trees that mature at half or a third the size of maple trees is they will fit on the side of the street where the electricity lines are strung up on poles. This quaint old way of delivering power to the people seems unlikely to change, in my lifetime anyway, so the trees must shrink to avoid the gross mutilation you find when big trees clash with utility cables.
There is another reason the urban avenue has changed. The old model was of identical trees lining both sides of the street, to provide symmetric uniformity that produced marvelous effects - majestic American elms coming together 60 feet above the pavement to form pointed arches. But such plantings are risky, because the arrival of a new pest or disease could devastate them.
This is precisely what happened with the elm, ruined by the beetle that brought Dutch elm disease. In the upper Midwest, where green and white ash trees defined whole neighborhoods, the emerald ash borer arrived 20 years ago to wipe them out. ( Some cities had half their canopy given over to ash.) On the West Coast, the disease sudden oak death is a problem, and, in the South, the ambrosia beetle is a serious pest. In Washington, we had come to rely too heavily on red maples and northern red oaks, with new diseases beginning to threaten the latter, at least.