American University's rejuvenated landscape

Thursday, November 4, 2010

Trees are the teachers of the plant kingdom. They teach us the virtues of planning, patience and the idea that we can improve planet Earth in our lifetimes and beyond.

These thoughts spring to mind as I am walking around the campus of American University in Northwest Washington, taking in the autumn colors. If you haven't been to AU in a while, you should go. The place is full of tree huggers, and it shows. A staff of landscape architects, arborists and groundskeepers has worked to retrieve and rejuvenate a 75-acre sylvan landscape that had been in sad decline. In the intervening dozen years or so, they have demonstrated that (A) trees that are taken for granted will suffer and (B) you can turn a woodland around rather rapidly if you have the will.

My visit also reinforced this lesson: Choice trees grow quite quickly and can start to have presence in five years and real stature in 10. In other words, please stop planting Leyland cypress and pick trees that are prettier and better suited to their location.

Sometimes trees grow far more quickly than even the textbooks can imagine. This has to do with soil conditions, groundwater patterns and the general microclimate of a site. In the sheltered back corner of a high-rise dorm, a place that sorely needed softening, five deodar cedars have just taken off. Planted as six-foot nursery orphans nine years ago, the trees stretch to 60 feet. Their pendent boughs are soft in texture and dark green highlighted with silver.

Nearby, a grove of dawn redwoods has doubled in size in the past 12 years, while a small stand of young ginkgos planted two years ago will answer the redwood's orange foliage with a bright yellow display in the next week or two.

We are seeing a young arboretum in stages of adolescence. Like the ginkgos, many of the trees are years away from their majestic maturity. This is commendable. Arboretums should be in a constant state of replenishment because old trees die. Even in youth, however, the beauty of the trees' autumn color is evident. The shrubby bottlebrush buckeye provides sweeps of bright yellow, the dogwoods are now a deep maroon, the blackgum trees are turning scarlet and even some of the oaks have taken on a warm golden glow.

AU landscape architect H. Paul Davis and his colleagues have planted more than 1,200 trees in the past 12 years, along with thousands of shrubs and perennials. This attention to an ailing environment has coincided with the arrival of major new buildings and a strategy of landscape shifts: Underground parking garages support green roofs; old roads and lots are being torn up for new plantings, fresh paths and sitting terraces.

For Davis, these improvements flow from a philosophy based on gardening rather than landscaping. The difference? Gardening is a continuous stewardship of plants and acceptance that they grow and change; landscaping is the idea that an area can be made pretty with the instant installation of "plant material" and a dollop of mulch. Or as Davis says, "Put some shrubs against the building and call it a day." That's not for the tree team at AU. "We aren't doing landscaping," he said. "We are doing a garden."

This care also requires an understanding that trees and construction don't mix. In an institutional setting, you have to be especially vigilant against destructive carelessness, though the same rules apply to the home landscape. You must create an awareness, Davis said, that certain unthinking practices will seriously harm trees, such things as placing heavy construction equipment on root zones and digging utility trenches through them, and piling soil over roots and damaging bark.

The students, understandably, are taking ownership, flocking to the shade and shelter of the growing canopy. After the Katzen Arts Center was built on Ward Circle, students planted more than 100 trees next to Massachusetts Avenue.

Like many of the students, some of the trees are from distant lands. The tree selection also moves beyond the normal limited plant palette of public institutions. In one sitting area in the quad, a small round tree named Maackia amurensis is 15 feet high and as wide, about two-thirds grown. It is valued for its clean foliage, symmetric outline and fragrant white flowers in summer.

On the western side of the campus, visitors will find four specimens of the Korean evodia, another rare and dainty tree, this one blooming in June. Davis's colleague Michael Mastrota is eagerly anticipating the arrival of a weeping Alaska cedar. This is a fine-textured conifer with layers of weeping branches. It grows at a moderate rate to 40 feet and would make a splendid specimen in the Washington garden, doubling as a screen.

In a period of deep concern about the future health of the planet, surrounding students with beautiful trees seems an enlightened step to take. These young men and women may not know the trees by name, but they surely feel the plants' nurturing spirit. To borrow from an Irish proverb: We live in each other's shelter.

A brochure and audio tour of the American University campus arboretum can be downloaded at Click on "walking tour." Guided tours are available for groups. Call 202-885-1145.

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